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njit-etd2002-027 - New Jersey Institute of Technology

1. functions 70mm sz 9 9 SE As Preparatory 20 00 1 1 f f GOO Positioning in Rapid 25 01 os 05 GOI Linear Interpolation Boj f S a NEM QUEE UMEN ae dcc qux liu 0 0 eere ECXNMENMNECTENE ANM NEENME HZ QOUN a E 45 121 l l o E E A ON MEA UNE NM EM HEREIN E PENNE ae ONE NEN NEM INE ee e Le0 p A p et qo d s nl 2 sem pos ot 0 Jos f J To o CE ERE ERE E e aaee Es eee Ew MEE E UMEN A a 8 0 oo l 90 T 1 05 MOS Spindle OFF Programming of MILLING Operation sf J con imeremenai programm incremental programming oo 1 3 06 T3 4 end mill aos Do So To 1 900 OS m BI NNNM ee E NAME NN NEN UNUM MEET f p pep I BC 179 F ee 29 ee Jrz Jo o o ee DENN NON E590 Aa a b LL ee a ee Ae a a a CO R NEN es ee ee eee aof 1 jo LLL 145 qq 1 pdoy L5 ho uu 7 102 103 g and Milling Program 0 5 inch R M30 Exit of program Jump to Start G02 circular interpolation cw G03 Circular interpolation ccw J 0 5 J 2 0 5 G90 Absolute units programming oe v o M m olS lo Sle Sloe Se emeiegg S mig RS Natit v TY oO SIS mias Cile eel e BIA calle MINION eo en en APPENDIX D CREATING A SIMPLE ROBOT BY USING WORKSPACE3 The following tutorial is designed to match the inte
2. 10003 00008 00490 00002 A001 Jr x JONA A000 A001 On AO0101 10003 10002 400101 122 Table Petri Net Presentations of the Sequences of LLD Continued 10003 A0010 ADO0104 00490 ADOIM AQ0109 O000Q moos agno ATOW 00490 AOS 00000 Unete RC RC ERG 10033 i Hu V o AG nnns L 00490 001 A0013 10081 10007 A0020 AONB 4 ee 0049 AO0135 00007 4002 E t AWS 123 Table H 1 Petri Net Presentations of the Sequences of LLD Continued _ Lr mois 00011 0049 00010 A0014 TL TEE AO0050 AO001HM 00012 00111 10015 400110 10014 1014 AO01M AOO0116 0049 AOOllD 405 A00202 00009 R W014 000W AO0116 00490 Sie e A001 REFERENCES 1 Andrea Bobbie et al Comparison of the methodologies for the safety and dependability assessment of an industrial programmable logic controller Available at http www aidic itAitaliano congressi esrel2001 webpapersesrel2001 85 pdf 2 C K Gallopade and D M Tisbury Familiar and Emerging Logic Control Frameworks A Critical Comparison Control Engineering Magazine Submitted December 6 2001 Available at http www controleng com archives 2002 ct10202 01 020202umich pdf 3 C Ray Asphalt Robots and Manufacturing Automation John Wiley amp Sons Inc 1985 4 David A Geller Programmable Controllers Using the Allen Bradley SLC 500 Family Prentice Hall Inc Englewood Cliffs NJ 2000 5 F
3. Rot Y O0 sin cos 0 sn O cos 0 0 0 0 0 0 0 l cos sino 0 0 sin cos 0 0 Rot Z 0 0 O A 0 0 gt Figure 3 5 Rotational axes around X axis by angle The program below traces the robot from an ISOMETRIC view It consists of three types of statements auxiliary statements geometry statements and motion statements The first five statements in the program are the auxiliary statements The program begins with the declaration of the program name which is DRILING Then it declares the language Karel2 the memory is 1024kb the name of the robot IBM 7535 and then it moves to teachpoint declaration then there are four teaching points and their positions 48 are defined early in the table 3 1 these teachpoints are classified as geometry statements For the last category of statements motion statements There are many commands illustrated as the following the workpiece moves to a determined position Then the robot arm comes above this position TP2 moves the drill down TP3 rotates the drill TP4 and then the robot arm moves to home and repeats the cycle again and again The motions of the conveyors and the robot are completely controlled by PLC PROGRAM DRILLING LANGUAGE KAREL 2 MEMORY 1024 ROBOT IBM7535 TEACHPOINT DECLARATION VAR TP1 POSITION TP2 POSITION TP3 POSITION TP4 POSITION BEGIN JINCLUDE 2 MOVE OBJ NULLOBJECT 1 201 31 709 62 208 31 250 MOVE TO TP2
4. Y Control of multiple machines by one computer Y Improve computation capability of circular interpolation 31 v Part program stored magnetically in bulk memory in a central location Disadvantages Y High investment Y There is problem when the central computer goes down 2 3 3 Distributed Numerical Control DNC CNC As the number of CNC machine installations grew during the 1970s and 1980s DNC emerged once again but in the form of distributed computer system or distributed numerical control DNC For both DNC and DNC CNC systems the machine operation data can be reported to central computers for the provision of workshop management information and for the incorporation of the machine tool and other manufacturing equipment into a large integrated system There are several ways to configure a DNC CNC system as shown in Figures 2 19 a amp b Figure 2 19arepresents switching network configuration and Figure 2 19b represents local area network LAN DNC Computer Data switching box Figure 2 18a Configuration of DNC switching network 32 DNC Computer Satellite Satellite Compute Computer b MT Machine Tool Figure 2 18b Configuration of DNC LAN 2 4 NC Part Programming The following four part programming methods are used to program NC machines 1 Manual data input MDI 2 Manual part programming 3 Computer assisted part programming 4 Part programming using CAD CAM The four method are shown s
5. sese ee M 2 41 Dimensions of the chamfered block oerte En eae esas see eeBESE 3 Process flow from simulation to translation eene 24 QOtThosonal JOM ae eR eB ceu N rex eoe ipee Quat ase elata be peo ecu thats 232b otauonal JOLIE bet Er E MIRA D Dites Eb estadio dd Dea FUR 32e REVOVNE JOD RR T UU I Em 3 3a Rotational joint NCC CR PERRO DBO DWISOBS O san eei rtu a Dad tsi tentant eee teed DA MAC AI POUL sesso select cy aeewe sets sce pete case Sees coted anes ie eases etassiaeanreanets 3 5 Rotational axes around X axis by angle Ooo eee ceeeeeeeeeeeeeeeeneennenes 36 gt lt CAD modeling for GE P 50 f0DOL ean n E 3 7 CAD modeling for IBM 7535 YODOE i poete tuit oa a e 4 1 Basic functions of a machine vision system eee 4 2 Matrix of picture elements where each element has a high intensity value corresponding to that portion of the image 4 3 Diverse applications for which machine vision has been implemented AA JBSLl featuie SeDsOLioc erus iere eee ne tet demi p pitt A xiii Page 26 2 28 29 20 30 31 32 33 34 36 40 42 42 42 43 43 43 41 49 49 52 53 55 60 LIST OF FIGURES Continued Figure AS Tooth brush NRCS Ol usce corone ote bdese um doin e acetate del Eae pese Uu AES aude 4 6 Model of the inspected workpart rr E A 5 1 Examples for input and odi devices a Limit swit
6. In today s fast automated production Flexible Manufacturing Systems FMS play a very important role by processing a variety of different types of workpieces simultaneously This study provides sabie information about existing FMS workcells and brings to light a unique concept called Programmable Automation Another integrated concept of programmable automation that is discussed is the use of two feasibility approaches towards modeling and controlling FMS operations the most commonly used is programmable logic controllers PLC and the other one which has not yet implemented in many industrial applications is Petri Net controllers PN This latter method is a unique powerful technique to study and analyze any production line or any facility and it can be used in many other applications of automatic control Programmable Automation uses a processor in conventional metal working machines to perform certain tasks through program instructions Drilling milling and chamfering machines are good examples for such automation Keeping the above issues in concern this research focuses on other core components that are used in the FMS workcell at New Jersey Institute of Technology such as industrial robots material handling system and finally computer vision FLEXIBLE MANUFACTURING SYSTEM UTILIZING COMPUTER INTEGRATED CONTROL AND MODELING by Yahia Mohammed Al Smadi A Thesis Submitted to the Faculty of New Jersey Institute of Technology
7. It is called R joint and is shown 43 in Figure 3 3a The twisting joint permits a rotary motion but the axis of rotation is parallel to the axis of the two links It is called T joint and is shown in Figure 3 3b Input Output input 3 output 3 Figure 3 3a Rotational joint Figure 3 3b Twisting joint GMF M1 Robot GMF M1 robot was shown in Figure 1 11 has a mechanical gripper and a cylindrical configuration It consists of a vertical column relative to which an arm assembly can be moved up and down This robot consists of an orthogonal joint twisting joint and linear joint The orthogonal and twisting joints were discussed earlier In linear joint the relative movement between the input link and the output link is a linear sliding motion with the axes of the two links being parallel it is called L joint And shown in Figure 3 4 Input Input Figure 3 4 Linear joint 44 3 5 WorkSpace 3 Robot CAD System With the assistance of modern computer technology design simulation control planning management or any area of manufacturing is no longer difficult to model It has been said that 3D simulation has revolutionized the way that engineers can work 6 The following sections describe how the computer simulation done by Workspace 3 was used to simulate the drilling operation done by the IBM 7535 robot Workspace 3 is widely used in industry tool to design model and simulate It can be used
8. MOVE TO TP3 MOVE TO TP4 MOVE TO HOME END DRILLING Figures 3 6 and 3 7 show examples of robots used in NJIT FMS drawn by the well known CAD package AutoCAD These files can be exported and imported by 49 Workspace 3 The whole FMS cell can be displayed by CAD as shown in Appendix A which shows many drawings for NJIT FMS Figure 3 6 CAD modeling for GE P 50 robot Figure 3 7 CAD modeling for IBM 7535 robot CHAPTER 4 COMPUTER VISION INSPECTION 4 1 Introduction Over the past twenty years computer vision has been used in wide array of manufacturing applications including robotics electronics and semi conductor manufacturing These were among the first to embrace the technology and currently account for about half of the computer vision applications found on factory floors However acceptance is rapidly growing throughout the entire manufacturing sector with computer vision systems now in place in food processing pharmaceuticals wood and paper plastics metal fabrication and other industries Until recently the limiting factor in vision based robotic control has been the ability to perceive and react in complex and unpredictable surroundings Computer Vision and Image Understanding is a prestigious journal devoted to the dissemination of research in areas relevant to computer vision Papers are published on all aspects of image analysis from low level processing as in early vision to high level symbolic proc
9. friction of leadscrews with the rolling friction of ball bearings placed between the screw and nut members A ballscrew performs at very high mechanical efficiency and with much less energy consumption for a given load As compared to conventional screw drives predictable wear life and smooth quiet operation are also obtained 8 21 Figure 2 4 Ballscrew Mounting Ballnuts Ballnuts are typically mounted in mating flanges as shown in Figure 2 5 A to restrain the nut from rotation and translation and are sufficient when loads are axial If significant side loads are present support rails should be used in parallel with the ballscrew The longer and the smaller the ballscrew diameter the greater the possibility of column loading limitations 8 a b Sphencally Ground Hall Screw Pretensioned Assembly Back lash Prex Harg Mounted c Figure 2 5 Mounting Ballnuts and Ballscrews a conventional screw b c Ballscrew 22 The servomotor is hard mounted on the end of a ground screw that is coupled with a recirculating ballnut assembly which allows zero screw backlashes e Tools All parameters associated with the tool such as diameter length rpm and other geometry features should be saved in CNC control memory The controller of CNC machine should have the capability to chose the right tool for that dedicated program Tools examples are shown in Figures 2 6 and 2 p CNC Tooling OS o
10. arcs and places so that the model become marked to facilitate study and analyze the reachability tree The final Petri net model for the entire FMS cell is shown in Figure 6 7 89 e s a Y morc Lyc X a LIL Figure 6 7 Final Petri net modeling for NJIT FMS cell A Petri net model can be developed for a manufacturing system given a list of machines a list of operations and their relations The modeling procedure is as follows l A simple Petri net first chosen which describes the aggregate level system and satisfies the safeness liveness and reversibility conditions 2 Stepwise refinement of this PN is done in a manner which maintains the 90 structural properties while adding process and control details 3 Stepwise refinement is accomplished by replacing places by basic design modules that describe more detailed logic for the process represented by that place These basic modules are defined as sequence PN parallel PN conflict PN and mutually exclusive PN 4 If this method is used the desirable detail will be achieved and the structural properties guaranteed 6 5 2 Analysis It can be noticed that e Since each marking has its element being 0 or 1 the net is safe e Since the reachability graph has a directed circuit containing all the transitions at least once the sub net is consistent e From an
11. not in the CAD data base These geometric models of the new robots and devices can be automatically combined with their unique kinematics description for future animation in PLACE 41 The COMMAND module is used for programming the robots off line COMMAND is used in conjunction with PLACE and a specific robot program translator to generate a complete robot program that can be downloaded to and executed on the robot controller A powerful feature of COMMAND permits the user to associate groups of logic instructions with specific robot positions defined by a place sequence The ADJUST module is used in conjunction with a probe attached to the robot end effector It is designed to modify the locations of the robot end effector in a PLACE workcell so that the physical dimensions of the robot match the actual locations of the corresponding end effector in the actual FMS cell This is a fast and efficient way of resolving any discrepancies that may exist between the physical dimensions of the actual robot and the dimensions of the simulated model and also between the actual cell and its computer model 3 4 Robot Anatomy All robots have joints and links The anatomy of robot is a description of its joints and links IBM 7535 Robot The IBM 7535 robot was shown in Figure 1 9 has special end effectors to perform drilling operation The robot has SCARA configuration The arm is very rigid in the vertical direction allowing the robot to perform dril
12. part in a bin d T N The robot places the rejected part in another bin The robot loads the cart with a new blank part Cart available to be released to the system GE P 50 robot available Milling machine available Vision system available for inspection purpose P13 Raw material from the parts presentation station P10 Are added to check this subnet for its properties Table 6 6 Reachability tree of PN Modeling for CNC Milling Machine GE P 50 Robot Vision System and Part Feeder Pens Mommies fila 3 a s e z s 9 iol e enabled 1 2 3 4 445 7 10 11 12 mialy 1 0 0 0 0 0 0 0 0 0 1 1 1 Hj Eq 3 5 a 07 9 09 0 HOS 0 3 oT oe 2 ur ojoji ojojojo o o 0 J O 1 I Hj L3 u 910 70 1 0 0 0 0 0 01 1 0 4 t P 3 d 9 peq0 0 3 1 9 190 0 009 14 T L5 1 n4 oo po ovo oprroo 0 0 T3 r0 1 L amp us ojjofjojojofof ojojojoj if f 7 ue jojojo oj o 0 0 1 0 0 0 1 ity Los w 0 o or0 90 9 0 0 1 0 t T0 E 9 us mz o ooo oo oro i roro 1 1 0 FE 3o u9 0 o oojpe o o roO T IJ T1 po v jrijojoj jojorojojoj o 1 1 it Figure 6 4 shows from right to left the modeling made to reduce the number of arcs and places so that the model become marked to facilitate study and analyze the reachability tree 86 The PN modeling for the drilling station is shown in Figure 6 5 and the description for the places and transitions is pres
13. process being controlled Compare the information wth control information supplied by and stored in the program 3 Deci de whether the control action is needed 4 Execute the control action by transmtting signals to the out put interface Look again at the 1nputs Figure 5 2 Schematic diagram of a PLC controller 68 5 4 PLC Computer Functions The functions that a PLC can perform are 1 Control of each process station 2 Production control 3 Traffic control 4 Tool control 5 5 Advantages of PLC PLC use offers the following advantages 1 Increase system availability 2 Decrease downtime requirements to recover from failure 3 Decrease cost from material and man hours for installation 4 Increase system feasibility 5 Increase flexibility to meet new requirements 5 6 Basic Logic Gates used in PLC AND OR and NOT A logical AND gate outputs a value of 1 if all inputs are 1 A logical OR gate outputs a value of 0 if all inputs are 0 Logical NOT gate output is 1 if the input is 0 and vice versa Table 5 3 shows the three basic logic gates with their presentations as Logic gate electrical circuits and LLD presentation 69 Table 5 3 Basic Logic Gates Used in PLC FALLS YEN SE ar a S20RS3 L2 52 S3 L2 For better visualization of how the programming language LLD is designed see the example shown in Figure 5 4 In the first rung pressing input switch I 1 1 activates the output O 6 1 which can be any out
14. project is a feature sensor system The feature sensor contains area tools which can be configured in different ways There are quite a few components of the system which need to be configured for the application The software used to configure and edit the system is the SensorEdit software supplied by Itran The software is used on a PC which contains a link card and cable used to communicate with the IVS 14 The pixel resolution for Itran IVS system is 320 x 240 pixels The IVS system has sub pixel resolution capabilities to 1 32 of a pixel This is done by using mathematical operations of differentiation and interpolation on the surrounding pixel values Because of this technology the accuracy of the system is greatly increased The total processing time of the IVS system is constant of each inspected part at 67 msec Time is needed for scanning at fixed rate and the implementation of a parallel 57 processing technique The system is actually processing four images at one time There are four steps for each inspection and each of the four images that are being processed advance to the next step The four steps are as follows 1 Read inputs acquire image apply locator and lightmeter 1 Apply the vision algorithms 2 Process the worksheet calculations 3 Process outputs 4 3 1 Obtaining an Image The first step in obtaining an image is to place a part in the inspection area and within the field of view Using the software
15. repeatability of 0 005 DC servo drive used for palletizing and its configuration is cylindrical Figurel 11 shows the GMF MI robot Figure 1 11 GMF MI robot 12 1 5 3 Material Handling and Storage System The function of the material handling system is to provide convenient access for loading and unloading workparts and should be compatible with the PLC computer control Figure 1 12 shows the Cartrac material handling system Figure 1 12 Cartrac material handling system The type of conveyor used in this system is cart on track it is shown in Figure 1 13 The cart rides on a two railed track contained in a frame that places the track a few feet above floor level The carts are not individually powered instead they are driven by means of rotating tubes that run between the two rails A drive wheel attached to the bottom of the cart and set at an angle to the rotating tube rests against it and drives the cart forward Here regulating the angle of contact between the drive wheel and the spinning tube controls the cart speed When the drive wheel is perpendicular to the tube the cart doesn t move as the angle is increased toward 45 the speed increases In this way the carts can achieve relatively good accuracies of position 27 13 Conveyor rais RF ec wu ME Conveyor E ne rA Figure 1 13 Operation of cart on track conveyor 1 5 4 PLC Logic Controller GE Series Cell Controller The PLC is the traffic
16. the actual position and velocity of the axes and instruct the DPU to read new 24 instructions from the part program when the operation has been completed Figure 2 9 illustrates a schematic diagram of a CNC machine MCU Machine Control Unit DPU Data Processing Unit CLU Control Loop Unit Figure 2 9 Schematic diagram that shows the MCU DPU and CLU used in a CNC machine 2 2 3 Coordinate System The most basic important programming concep of numerical control is to provide the mean of locating the tool in relation to the workpiece Figure 2 11 below shows three major programming axes X Y and Z However there are three more axes a b and c representing the motion around each axis X Y and Z respectively The axes maybe referenced on the bases of two major systems fixed zero system absolute zero and float zero system The fixed zero system is a numerical control system in which all positional dimensions both input and feedback are given with reference to a common datum point Float zero system is a characteristic of a machine 25 control unit that allows the zero reference point to be established at any point along an axis 9 Z xis bs Z E M P D i ext 7 Y Axis Ce 7 mo Workpart b dame ces 7 b X X Y Axis ens A O Xe Axis di B Worktable 3 Z Axis Y Figure 2 10 Visualization for coordinate system 2 2 4 Motion Control System The motion control sys
17. the application was downloaded to the IVS each part was manually placed in the inspection area to measure the area tool value for that part Once all the values were obtained the output of the system was configured This procedure is used after uploading an image a new image from the camera and positioned the locator tool these tools are listed as following 1 Select Edit Arc Tools 2 Select a Brush Shape 3 Paint an Area Tool 4 Select Inspection Method 5 Repeat For Additional Tools 4 Resolve Tool Conflicts 5 Program the I O 6 Program the Math Worksheet 7 Download and Test the Application 59 4 3 3 Screen Messages RS232 Outputs and Discrete I O The IVS system allows one to create outputs in three different forms discrete I O screen messages and RS232 The output can be configured using Boolean logic or can be set to true or false The discrete I O is opto isolated hardwired outputs which can be wired to any external device The screen massages are displayed on the vision system display monitor The RS232 output information can be sent to a wide variety of RS232 terminals including PC s and PLC s Screen messages and discrete I O are created using Boolean logical formulas A sample formula could be IF AREA1 gt 24000 AND AREA 1 26000 TRUE FALSE Here 24000 is the least number of threshold pixels and 26000 is the maximum number of threshold pixels The AREA is the name of the area tool TRUE is th
18. used in Logical Controller eeeseeeesss 69 Reachability Tree for the Figure 06 2 rerin en E A vete aufus eds 79 Manufacturing Processes and Their Applications by PN 80 Places Events and Transitions for Material Handling System yos ies 82 Reachability Tree of PN Modeling for Material Handling System 83 Places Events and Transitions for Milling Machine GE P 50 Robot Vision System and Part Presentation Station Feeder 85 Reachability Tree of PN Modeling for CNC Milling Machine GE P 50 Robot Vision System and Part Feeder essse 85 Places Events and Transitions for Drilling Station ee ceeeeeeeeeeees 86 Reachability Tree of PN Modeling for Drilling Station 86 Places Events and Transitions for Chamfering Station 87 Reachability Tree of PN Modeling for Chamfering Station GMF MI Robot and a 100 Tool crib 000 0 eeeeeeeccereceeeeseeeeteesseeeeeeeneees 88 Comparnsom or PN and ELED niti ee en A tesa N 92 Formulas Used for CNC Programming cccccccscccccsceecenececereeeeeseeeeceseeneeesees 99 Drilling and Milling Pro stain ees ers ERI n E e 102 unfer r N tesa eamnnenees 106 OUEDDUCLISE o roodo Dee Remote D tu a o a Ubri sins 108 Sequences Description for PLC Control Program eeeses 110 Petri Ne
19. 022 with OC 2 AO0136 latched Note i e the system start PB 2 was pressed again after the system stopped having run 8 Darts or a multiple of 8 parts through the system already Table F 1 Sequences Description for PLC Control Program Continued 115 Part Inspection at station 2 Seq No Lon OMNE olo acl and cart at station 2 and Robot gave signal NS 10070 Compare part accept reject masks with pr m present and decide on output ACCEPT Transfer Table 2 U J a2 5 Port 00050 001972 00193 Seq No Description Sensor The logic is essentially the same than the one explained for table 1 Thus the logic will not be explained in detail at this point For a detailed description refer to rung 96 114 Utilized switches analog to transfer 1 lt LS 10A 12A 14A 20A gt PC 11A oe z oc rs End of the program Seq No Description Sensor The first scan after initial power on was to establish constant and clearing conditions At this point then the power up coil is finally energized so that that actual process can start under predefined conditions The controller jumps to step 1 for a new scan o9 pt mI 00480 End of Program Chamfering Operation Seq No ____ Robot moves to positioncartC lt lt NS gt Execute the program of picking up the part and place it in the jig o
20. 2 et oan testatus TICONCLUSIONS 2igetaeseiecctcehttsectdebepset iege Mu RAO Mu IU DN EAM ix Chapter APPENDIX A APPENDIX B APPENDIX C APPENDIX D APPENDIX E APPENDIX F APPENDIX G APPENDIX H REFERENCES TABLE OF CONTENTS Continued Page FMS DRAWINGS SHOW NJIT EMS 94 FORMULAS THAT CAN BE USED FOR CNC PROGRAMMING ii usto eaten noa idi died EUM ME 99 DRILLING AND MILLING OPERATIONS PROGRAM 102 CREATING A SIMPLE ROBOT hiiieeediie tolo tot ohh ne 104 INPUT AND OUTPUT PORTS USED IN PLC TO CONTROL THE FMS eaoin E oreet nen caue 106 DESCRIPTION FOR EACH PORT AND SEQUENCE USBEDIN PEG tete ont RO UNI EE E cim aedta auus 110 PLC LADDER LOGIC DIAGRAM FOR NJIT FMS 117 PNUPRESENTA TION FOR GED bi i eesiitesEuc oput S REUS v pauta 120 H M 124 Table 1 1 2 1 2 2 3 1 5 1 3 3 6 1 6 2 6 3 6 4 6 5 6 6 6 7 6 8 6 9 6 10 6 11 B 1 C 1 E 1 EZ I H 1 LIST OF TABLES Page Comparison Between FMS and Conventional System Performance 6 Classification for Number of Axes of CNC Machines esee 27 Olivetti Machining Center Program Chamfering Operation 36 Points Coordinate with Joints Motions of the Robot eessssse 46 Inputand Output PLG DEVICES oiii deett pa Ee Et E Recta ua gute eed set us 66 Basic Logic Gates
21. AN ANOR position at X5 i E Availability of cart halting Cart loaded on the transfer table TT2at X7 Availability of TT2 at position X7 Cart transported to position X8 by TT2 Py8 Availability of TT2 at position X8 Cart being loaded on transfer Cart moving from loading station to X2 table TT2 t2 Cart being loaded on transfer table TT 1 7 TT2 and the loaded cart move together to X8 TT 1 and the loaded cart move together to Cart unloads from TT2 and t3 8 X4 moves to X1 X X X X X Cart unloads from TT1 and moves to Moves back from position X8 to X7 t t a i t drilling station l Cart moves from drilling station to X6 t TT1 moves back from position X4 to X3 Table 6 4 Reachability Tree of PN Modeling for Material Handling System o Frere rete po qeuo UOHISURL j DIM t10 84 The PN modeling for the milling machine GE P 50 robot vision system and part presentation station Feeder the modeling is shown in Figure 6 4 and description of places and transition for this system is shown in table 6 5 Its reachability tree is shown in table 6 6 Figure 6 4 Modeling for milling machine GE P 50 robot vision system and Part presentation station Feeder 85 Table 6 5 Places Events and Transitions for Milling Machine GE P 50 Robot Vision System and Part Presentation Station Feeder Milling machine loaded with raw material by GE P 50 robot PS P6 The robot places the accepted
22. Copyright Warning amp Restrictions The copyright law of the United States Title 17 United States Code governs the making of photocopies or other reproductions of copyrighted material Under certain conditions specified in the law libraries and archives are authorized to furnish a photocopy or other reproduction One of these specified conditions is that the photocopy or reproduction is not to be used for any purpose other than private study scholarship or research If a user makes a request for or later uses a photocopy or reproduction for purposes in excess of fair use that user may be liable for copyright infringement This institution reserves the right to refuse to accept a copying order if in its judgment fulfillment of the order would involve violation of copyright law Please Note The author retains the copyright while the New Jersey Institute of Technology reserves the right to distribute this thesis or dissertation Printing note If you do not wish to print this page then select Pages from first page to last page on the print dialog screen The Van Houten library has removed some of the personal information and all signatures from the approval page and biographical sketches of theses and dissertations in order to protect the identity of NJIT graduates and faculty ABSTRACT FLEXIBLE MANUFACTURING SYSTEM UTILIZING COMPUTER INTEGRATED CONTROL AND MODELING by Yahia Mohammed Al Smadi
23. E 5 gt lt SEE 3 gt Latch that cart is present on transfer table l Note Latched with lt PC 11 gt and reflecting tape on the carts the tubes drive the cart for another 2 sec To lt SEE 3 gt ensure that it is at the end position AO0105 Energize transfer drive toward away position Only if conveyor system initialized lt SEE 2 And cart on transporter PC 11 SEE18 gt 111 00004 AOO0101 AO0107 O000 O0005 AO0104 O0003 112 Table F 1 Sequences Description for PLC Control Program Continued Si position Note AQO102 is activated by LS 20 gt The tubes are driven for another 3 sec AO0103 Energize push pull solenoid to allow cart to exit to inspection station 2 Mechanism is depressed in step 11 _ lt LS 20 gt 2 PC 11 gt O0002 SEE 5 SEE 20 Inspection Station 1 Description Cart 1s off table Latched with transferred table 1 clear NO Count carts existing table and reset after 4 Dart 22 Counted with No 20 AO0102 m M lt Sensor gt o6 ad 12 LS 12 LS 21 O0205 NS P Part present at station 2 Only if cart at inspect Station 2 And optomation result first part present mask Robot Control Logic Description Robot job select permit only if system enabled and robot not in motion and machine tool not in jog mode NS AO0129 and cart
24. EW eimir A T S Geometrical properties Tor the 001 i5 Se EHE ve rx lo npa aee bu Rp ani Tools which are used in a NASA II milling machine D DING OPE PAN OM oe seosse o tn ee tote pos tube ar use eon Fist ta S Configuration of CNC machine control unit eese Schematic diagram that shows all of MCU DPU and CLU used In NC TAC INC soci ec deii to oni o aa pecsiudeicsapeutb aa es tee Ee CM LA Visualization for coordinate system sesessessssssrrerrrerereereeerereeeeroresssessesesse Point to point control System imos eet nae atos eo usare e Less u acu bs xii V S ve e WO Oo CO 00 Nn A U LIST OF FIGURES Continued Figure 2A2 Sthareht Cut COMMON systemer a acta eo Fonte bein M ER d tea D MM 243 COMLOUTINE Control SYSLEM ue otto ure Db tba s ved uisque eeentancenst 2 14 Classifications of the CNC machines according to their axes PAREM DIMUS ICE Oo LI ZAG Closed Joop Syste uino dto Mode a ese arto Se De buo Du e ees eee 2 17 General configuration of a DNC systems Connection to MCU is behind the TAPS reader aee et motio ees Eat o Oa DISP E Meere belio sut 2 18a Configuration of DNC Switching network eese 2 18b Configuration of DNC LAN configuration cece eesseeeeeteeeeeseeeneeeaes 2 19 Schematic diagram for part programming methods suse 2 20 Tasks in assisted computer programming
25. In Partial Fulfillment of the Requirements for the Degree of Master of Science in Manufacturing Systems Engineering Department of Industrial and Manufacturing Engineering May 2002 APPROVAL PAGE FLEXIBLE MANUFACTURING SYSTEM UTILIZING COMPUTER INTEGRATED CONTROL AND MODELING Yahia Mohammed Al Smadi Dr Kevin J McDermott Thesis Advisor Date Associate Professor of Industrial and Manufacturing Engineering Director of Cad Cam Robotics Consortium NJIT nse ee Dr Athanassios K Bladikas Committee Member Date Associate Professor of Industrial and Manufacturing Engineering Chair of Industrial and Manufacturing Engineering Department NJIT EIE LC ccc a LI EID LECHE Dr George H Abdou Committee Member Date Associate Professor of Industrial and Manufacturing Engineering Associate Chair amp Program Director Industrial Engineering Programs NJIT BIOGRAPHICAL SKETCH Author Yahia Mohammed Al Smadi Degree Master of Science Date May 2002 Undergraduate and Graduate Education e Master of Science in Manufacturing Systems Engineering New Jersey Institute of Technology Newark NJ 2002 e Bachelor of Science in Mechanical Engineering Jordan University of Science and Technology Irbid Jordan 1999 Major Manufacturing Systems Engineering This thesis is dedicated to my beloved parents and family members ACKNOWLEDGMENT I would like to express my sincere gratitude to Dr Kevin J McDermott for his invaluable guidan
26. LC TO CONTROL THE FMS The tables that follow show the input and output lists and their ports and nicknames for the PLC controller used in NJIT FMS cell for the process stations and IBM 7535 and GE P 50 robots Table E 1 Input List Input List 1 Load Unload Station DESCRIPTION Nickname Limit Switch 302 car present at transfer station 1 LS302 Limit Switch 303 transporter 1 at home position LS303 Limit Switch 304 transporter 1 at away position LS304 Limit Switch 305 transfer of cart clear of transporter 1 10004 LS305 Photocell contract for cart present transporter 71 10005 PCR201 Limit switch 307 cart present at work station 1 LS307 Limit switch 308 cart present at work station 2 LS308 Normal stop pushbutton PB155A Release station 1 pushbutton PB310 Release station 2 pushbutton PB313 Limit switch 402 car present at transfer station 2 10013 LS402 Limit Switch 403 transporter 2 at home position 10014 LS403 Limit Switch 404 transporter 2 at away position 10015 LS404 Limit Switch 405 transfer of cart clear of transporter 2 10016 S405 Photocell contract for cart present transporter 2 10017 PCR202 Limit switch 407 cart present at load unload station 10018 LS407 Release load unload station pushbutton 10020 PB4098 System run 10021 System start pushbutton 10022 Emergency stop pushbutton air pressure necessary 10024 2 CNC Milling Machine DESCRIPTION VO Ports Nickname Machine tool jog mode 10033 JOGMODE
27. Machine tool M22 10034 M22 106 Table E 1 Input List Continued Machine tool M2 1 M decode spare M decode spare M decode spare M decode spare OEM Emergency stop pushbutton Optomation Data bit 0 Optomation Data bit O Optomation Data bit 0 Optomation Data bit 0 Optomation Data strobe Optomation VPL run Optomation Data overflow Optomation error Optomation over temperature 10035 10036 10037 10038 10039 10049 10050 10051 10052 10056 10057 10058 10059 10060 107 M21 OPTODBO DATASTB 2 Robot DESCRIPTION Robot output 0 turn on Gripper Robot output 1 turn off gripper Robot output 2 close vise Robot output 3 robot clear of CNC Robot output 4 open vise Robot output 5 Robot output 6 Robot output 7 Robot output 8 Robot output 9 Robot output 10 Robot output 11 Robot output 12 Robot output 13 Robot output 14 Robot output 15 Robot in motion Robot abnormal welding condition Robot emergency stop I O Ports 10065 10066 10067 10068 10070 10071 10072 10073 10074 10075 10076 10077 10078 10079 10080 10081 10082 10083 Nickname GRP ON GRP OFF CLSCLMP ROBOTCL OPENCLP Camera 2 take PIX Robot Release STA 2 Robot in motion Table E 2 Output List Output List 1 Load Unload Station DESCRIPTION Enter transporter 1 solenoid Exit transporter 1 solenoid Transporter 1 tube drive forward direction Trans
28. Manufacturing Systems e Applied in an industrial setting of the components used for operations and control e Modeled the FMS workcell control process using Petri net approach e Integrated Petri net controllers and programmable logic controllers using a unique control system Automated manufacturing improvements will continue to satisfy the demands of industry These efforts will make the manufacturing more efficient and flexible These improvements can be in management control systems modeling and simulation scheduling and operations manufacturing processes and cost reduction techniques Those who are interested in this subject can be confident that these manufacturing principles will be adoptable to any change flexible to any industry and feasible for any cost 93 APPENDIX A FMS DRAWINGS SHOW NJIT FMS The five figures that follow show the layout of NJIT FMS cell from different views They are drawn by AutoCAD r14 Figure A 1 NJIT FMS SE isometric view 94 Figure A 2 NJIT FMS layout SW isometric view 6 IBM 7535 Robot a al GE Senes 6 30 inputs ports 40 outputs ports Dnilling Station B C SI Cartrac l Itran C amputer Conveyor System Vision System Loading amp Inspection Milling Station Transporter B Robot AutoCAD oSmartC AM Figure A 3 Schematic diagram for NJIT FMS 96 Figure A 4 Loading unloading process station L6 Figur
29. NK2 and then click on the snap onto object icon move axis edit Joint submenu of the layout menu drag the axis using the mouse button pressed down to the end of LINK2 click on the diagonal view icon 104 105 the robot is fully defined and may now be moved show kinematics edit robot submenu of the layout menu the joint distances and the offsets are labeled on the screen exact kinematics edit robot submenu of the layout menu select the 2R inverse kinematics template the A matrix constant the mathematics representation of how the robot moves for the robot are shown click OK a massage amperes saying math achieved with the inverse kinematics for the 2R inverse kinematics is now available for the this robot it can now be moved by specifying robot endpoint positions click on the top menu icon pendant change the joint one variable by moving the mouse over the up down button on the pendant and pressing the mouse button down repeat with joint 2 follows Pendant menu click the mouse at different points near the end point of the robot the robot moves to each position instantly or comes up with a massage explaining that the robot cannot achieve the position move home action menu the robot moves smoothly to its home position CP move action menu the robot moves smoothly to the current pointer move home action menu the robot returns to the home position APPENDIX E INPUT AND OUTPUT PORTS USED IN P
30. S11 grabs from a video camera a 2D image of the part to be inspected The image is processed in 16 7 milliseconds using Iran s proven and sophisticated gray scale technology Up to 128 feature inspections can be made on each image A powerful comprehensive set of math operations combines and manipulates the inspection results allowing that implement real time solutions It can be used to perform inspection and other tasks associated with manufacturing processes A built in shift register tracks parts and permits effective reject control even on high speed processes up to 60 parts sec Simplified System Integration The FS11 has been designed to simplify its integration into a manufacturing line Its features include e Built in material handling shift register for effective rejection control even on high speed processes e Integrated sensor and strobe circuitry for those systems requiring strobes e Built in user menu for system setup including options to control monitor display and camera setup Benefits Features e Fast All measurements made in 16 7 msec Pipelined processing allows rates up to 60 parts per second e Non contact 2D visual analysis of parts 62 e Easy to Use Graphic setup environment on MS Windows 95 or more Speed and response rate are unaffected by the complexity of inspection Automatic compensation for object motion and lighting variation e Communications RS 232 Discrete I O Built in shift register fo
31. Schedule Display Interactive Quality Setup Data CNC Data Production Status Inquiry Statuts Instruction Record Quality Control ag Data Management Tob Selection L 4 Production Record Gathering M 4 CNC Data Messagef Alarm Machine Monitoring Machine Control Production Measurment CNG Start Stop Data Data Data equirement Sensor CNC Controller CRT Operation stand Figure 1 3 Functions performed within the FMS hierarchy 1 4 Advantages of FMS The advantages resulting from the implementation of FMS have been studied extensively They can be summarized as follows 27 amp 35 Y Reduced labor cost Y Increased output Y Decreased manufacturing cost Y Increased flexibility Y Reduced lead time Table 1 1 shows the comparison between conventional manufacturing technology and FMS under three criteria s optimistic most likely and pessimistic Table 1 1 Comparison Between FMS and Conventional System Performance Conventional FMS performance F remeter in Pessimistic Mon Optimistic performance likel Percentage of machine time spent without part Percentage of time when the part is not being 70 35 2 7 worked on while machine is on Percentage of manufacturing lead me the part 95 es Jof s spends in moving or waiting it can be seen in the table above that in all cases the FMS systems has better performance than conventional systems 1 5 Componen
32. and activities coordinator for the FMS cell It controls all operations and functions of the processing stations and the material handling system It is responsible for carts flow control tool and production control and all the other control activities of the workcell The subsystem is shown in Figure 1 14 Figure 1 14 Control system used in NJIT FMS 14 1 6 FMS Layout Configuration The layout of the NJIT FMS has a loop configuration as it was shown in Figure 1 4 and illustrated in Figure 1 15 additional views for NJIT FMS wrokcell are shown in appendix A The parts flow in one direction around the loop with the capability to stop at any station a Ld Figure 1 15 NJIT FMS layout 1 7 Product Cycle One complete product cycle for the FMS workcell operates as follows eThe GE P 50 robot loads the four conveyor carts with blank parts he conveyor carts are indexed to the four process stations by the Cartrac material handling system Each process station performs its function concurrently Each part is indexed to the next process station Ihe IBM 7535 robot is programmed to execute the drilling operation on the part 15 eThe GMF MI robot picks the part and loads the Olivetti machining center for the chamfering operation eThe GMF MI robot also loads the tools from the 100 tool crib into the machining center The GE P 50 robot picks up the part with its vacuum end effecter and places it into the fixture installed on t
33. ans the system can be initialized from any reachable state For Petri net there are conditions that have to be furnished to understand the analysis of modeling and analysis of reachability tree The latter is considered to be an important tool for the following conditions l If all the places have one token at any firing stage which means the system is 1 Bounded and safe 2 If the system continues to produce tokens that means the system is live 3 If from any reachable state the system can be initialized that means the system 1s reversible 6 5 Case Study Modeling and Analysis of PN for NJIT FMS 6 5 1 Description and Modeling The material handling system of NJIT FMS cell was modeled using Petri net The modeling is shown in Figure 6 3 and the description of its places and transitions is shown in table 6 3 Table 6 4 shows the reachability tree for material handling system 82 Py t9 Py8 Figure 6 3 PN modeling for a material handling system Table 6 3 Places Events and Transitions for Material Handling System Event Description Event Description Availability of cart Cart available at the loading station X1 Waltins position at cl l T Availability of cart halting Cart loaded on the transfer table TT lat X3 Availability of TT1 at position X3 Cart transported to position X4 by TT1 Availability of TT1 at position X4 Px5 Cart available at drilling workstation at X5 Py5 AYaSoDY OLC
34. at station2 L3 2I the carts at this point must be empty the job select permit will automatically initiate the robot to load the first 4 parts Rung 58 Logic Down Counting from 4 to 0 LS 21 26 A ee A LS E E Sensor SEE 5 NS I00810 AO0129 When counter 0 i e 4 parts went through the system the coil initial 4 parts loaded AO0130 is ized and latched 113 Table F 1 Sequences Description for PLC Control Program Continued All three job selects require that 0008 l select Job 0 lt LATCHED gt 2 either job 1 Load initial 4 parts OR Job 3 Unload machine and inspect part 3 in case of normal system stop command LS 3 OR part limit Select Job 2 lt LATCHED gt Will select job 4 initiate A Robot Note After job select A 250 msec delay will ensure that data was transmitted and the external start permits O0087 and AO0131 LATCHED are sent to the robot controller The robot s servo motors will be shut off 1 e the robot disabled only when the emergency stop PB 4 is pressed The zero adjust O0085 will only occur if servo off O0086 is recovered by pressing recover PB 2 1 27 Turn gripper on Turn gripperon lt LATCHED gt ON with lt both received from EU L 3 10065 OFF with with controller output port 10066 EO 39 Only if power up Allow robot to get part only if cart i
35. bot input 10 Robot input 11 Robot input 12 Robot input 13 Robot input 14 Robot input 15 Robot job select 2 0 JOBSELO Robot job select 2 1 JOBSEL1 Robot job select 2 2 JOBSEL2 Robot job select 2 3 JOBSEL3 Robot zero point adj Or servo on ZEROADJ Robot servo off SERVOFF Robot external start EXTSTRT Robot external stop Robot emergency stop EESTOP Part is present station 1 PRTPREI Part is missing station 1 PRIMISI Part is accepted station 2 PRT ACP2 Part is rejected station 2 PRTREJ2 Robot job 2 selected Load CNC 00211 JOB2SEL Robot job 3 selected Unload CNC O0212 JOB3SEL 5 Reloading Station DESCRIPTION I O Ports Nickname Station 1 Table pointer O0400 PRTPTRI Station 1 Table pointer ea PRTPTR2 6 Functions DESCRIPTION I O Ports Nickname Power UP 00480 PWERUP System Enable 00490 SYSENAB Initiate 01024 INIT APPENDIX F DESCRIPTION FOR EACH PORT AND SEQUENCE USED IN PLC Table F 1 describes the sequences used in the ladder logic diagram to control the FMS cell and the names of each sensor and port assigned to each sequence It also contains some notes after certain sequences to explain further that sequence Legend NS No Switch i e software logic LS Limit Switch PB Push Button PC s Photocell SEE reference to another outlined logic to 0 OO48O Note only for new start when power up not energized System start Check if conveyor locations initialized 1 e at end positions Latched
36. ce support and encouragement throughout the research Special thanks to Dr Athanassios K Bladikas and Dr George Abdou for actively participating as members of the committee I would like to thank Dr R Kane and Ms C Gonzalez for their help and guidance to write this thesis Thanks to Mr Abuibraheem Choudry and Mr Sherif Mahdi for their help and constructive criticism Thanks are also due to the Robotics Training Lab New Jersey Institute of Technology where I gained most of my experience in the robotics and PLC fields vi TABLE OF CONTENTS Chapter 1 FLEXIBLE MANUFACTURING SYSTEMS aseseeeesssssssssssrssssseeeeeersrerresrerreeessees LE AMO GU UON P a E S E Pucerassieausiatly t2 Data di odium T S 1 3 Hierarchical Structure of an FMS Control System eese 1 4 Advantages of FMS eese RENTEN EAEAN Lo Components oL IIIS iios Dina yd ud ute b ON Lil Four Processme Stations 2 aoa oa epo GR Cere tirana ei cba coe 1 5 2 RODO cean to o tente Sco ed tucu I va iabmu p HEa M coe 1 5 3 Material Handling System and Storage eeeeeeeeeeess 1 5 4 Logic Controllers PLC GE Series Cell Controller Lo FMS Layout CODHPUFatuOL oco eia ote insi Sa eire Ced ei eee L7 product C yeleien al Ce vax den Puer br gd e uet eiesei vid dto sedem ted eerie 2 COMPUTER NUMERICAT CONTRODL iiiter ristotesterie i ten ee asian Zub Mod
37. ch D Photo detector c Solenoid auo eri io pex o reve vRe ELE FPE EFE Xe etos ana 5 2 Schematic diagram for the PLC controller eese 5 4 An example for LLD programming ccccceeeceeeseeeeeeeeeeeeeeseeeneneeeeeees 23 9 Loading state of the conveyor system e ee aee ees eH Ue neto Pu E se ead S9 Control DOIDIS suia io Up SERM I det itque aE 6 1 An example of processing which analyzes the mathematical modeline or aPN p c 6 2 Transition of tokens which is based on enabling and firing rules 6 3 PN modeling for material handling system esessss 6 4 Modeling for milling machine GE P 50 robot vision system and Part presentation station Feeder E dede ter Yee px E eec E eue podus 6 5 Modeling for drilling station ssec 6 6 Modeling tor chamterme SLALOM ooi pesa cogni fee ect daa R rM 6 7 Final Petri net modeling for NJIT FMS cell eeeeeeeeeeeessssss 6 8 Comparison between PN and PL nter ePi En Pea d ras AN abusu ade dus A l NJIPEMS Jayout SE 1sO0mettiC VIE Wie etes ee teo pese Cose Eee eei M nubi A2 NJIT FMS layout SW isometric View 2 iier eeee s tbcua ode er teieus ipn caa EI Enn A 9 Schematic diagram tor NJIT FMS 2iiieiccses 63 otto Coi dee aeuo qe obtu E reote eR Rea ein cia A 4A Loading unloading process station eese nennen PD d V SPD G 1 LLD diagram used in NJIT FMS ce
38. chematically in Figure 2 20 33 Computer assisted CAD CAM rite Pat Manual Program geometry Source Tool Path CLDATA Rem ote Post processor 3 iude proc CLDATA MCD McD Transmit to transmit to machine machine MCD M CD Machine Cotroller Machine Mh ee eee eee Figure 2 19 Schematic diagram for part programming methods 2 4 1 Manual Data Input MDI Under manual data input the operator manually enters the part geometry data and motion commands directly into the MCU prior to running the job MDI is useful in small machine shops It introduces NC to small machine shop without the need to acquire special NC part programming equipment 2 4 2 Manual Part Programming Under manual part programming the programmer prepares NC code using a low level machine language The program can be written by hand and coded as punched tape or other storage media or entered directly onto a computer equipped with NC part 34 programming software which writes the program onto the storage media Manual part programming is mostly suited for point to point drilling and spindle contouring jobs milling and turning when only two axes are involved 2 4 3 Computer Assisted Part Programming In computer assisted part programming the machine instructions are written in English like statements that are subsequently translated by the computer into low level machine code that can be interpreted and executed by the ae tool co
39. cutting and move in c co S x e c e a S D Un e 5 7 00 negative X direction Continue cut and move in negative Y direction Continue cut and move in Positive X direction Continue cut and move in negative Y direction Move away from Piece Rapid travel back to start N004 N005 N006 N007 NO008 G54 N009 7 00 0 000 i UA UJ Figure 2 22 Dimensions of the chamfered block 37 Drilling and milling program Drilling and milling operations performed as drilling four holes a hole in each corner The milling operation performs fabricating NJIT FMS on the top surface of the work piece Appendix C has the CNC program instructions to perform both operations In milling operation or any similar operation there are special motions for the cutting tool path such as circular motions these special motions have been formulated in mathematical formulas to facilitate their CNC programming Examples for useful formulas are shown in Appendix B CHAPTER 3 INDUSTRIAL ROBOTS AND INTERFACE WITH CAD SYSTEM 3 1 Introduction Robotics is a wide field currently sought after for research and development There are many robot software available today New software are released periodically they become increasingly user friendlier compatible with working the environment and possess more powerful features to control the robot However these software are designed to control one specific robot
40. d o 400101 30001 TSS sec AQ0106 Timer T 15 xc Figure G 1 LLD diagram used in NJIT FMS cell 117 118 in ADO10 wow Wel 00007 o 2 1072 ome 00001 A0010 00490 ADO100 Ap005 00001 00081 00062 00093 00084 00211 AD015 IMM 0001 AO0106 00490 o NN UL ad 00490 ier 0490 Ieee A0010 IL 00490 AD0l1Qd Lp DE 4 00002 0040 40013 00135 081 ajay aay ANNO 40013 x pin iar Ios 1003s z ES 0012 mare A D0129 AD0130 Fe A d 00490 AD0135 00007 pty 1 051 400152 E ADS 00017 k 106 a fee is js ANOS A00122 UL sio NEIN s 00490 E UL L 00480 10018 E Figure G 1 LLD diagram used in NJIT FMS cell Continued 119 Ie ob 00011 00490 O0010 400114 00012 L 400110 00012 ADW ADOlM 00012 lll pni 490110 1014 104 AO0114 AO0116 00490 A00110 agos 00009 sr E 101 00009 400116 00490 400051 000135 ADOLI7 Figure G 1 LLD diagram used in NJIT FMS cell Continued APPENDIX H PN PRESENTATION FOR LLD The following table represents each sequence of the LLD shown in appendix F and the Petri net representation for that sequence Table H 1 Petri Net Presentations of the Sequences of LLD lt a 101 00111 A 00101 400111 EM 400113 va See IO 00490 10008 SE 10006 00050 LAE Se i AOQ205 A COS 120 121 _Table H 1 B Net Presentations of the Sequences of LLD eotinaed OU 49 Cin Ly QD400
41. d y and are generally milling machines Four axes machines 28 CNC a Four axis CNC horizontal Lathe ud spindle milling machine Md up s Warki 7 CNC Milling Machine Five axis skin mill machine Figure 2 14 Classifications of the CNC machines according to their axes 2 2 6 Control Loop System The control loop system can be classified as open and closed loop system The significant feature of the open loop system is that there is no feedback system as shown in Figure 2 16 The information flows from the input media to the processor and storage memory through signal forms the latter sends them to the motor controller which drives the motor according to those signals A closed loop system is able to control precisely the position of the worktable through a feedback system Figure 2 17 shows a closed loop system which has the same operation as open loop system except the there is an additional rout for signal When the motor finishes the motion there a module is triggered which consists of a feedback device 29 and comparing unit to compare what was sent with what was achieved and direct the necessary correction Storage Memory Machine Control Unit Motor Controller Figure 2 15 Open loop control system Storage Memory Comparing Circuit Machine Control Unit LU Motor Controller Feedback Device Figure 2 16 Closed loop control system 2 3 Numerical Control Com
42. e then statement and the FALSE is the else statement The message display is then configured to determine what was to be displayed Each part is then assigned an output port which is used as hardware interface to the PLC RS232 outputs are configured exactly the same way as the screen messages and discrete I O The only difference is that the RS232 outputs setup needs to be configured in order to send the data in the proper format for the receiving device Items such as baud rate data bits stop bits and terminators are configured 4 4 The FS11 Feature Sensor The FS11 is an innovative low cost non contact feature sensor It is capable of high speed operation performing multiple feature inspections per part As shown in Figure 4 5 60 Figure 4 4 FS11 feature sensor The FS11 is primarily used following automatic assembly machining or forming operations Among the numerous uses for the FS11 are verifying e That holes have been drilled in sheet metal parts e The absence of flash on a modeled part e A subassembly has been properly added to the operation e lt A package is properly formed e A bottle cap is present and correctly shaped The FS11 delivers image derived process information to production control devices such as programmable logic controllers personal computers or any control system It can be directly connected to process machinery using standard industrial I O 61 On line operation The F
43. e A 5 Feeder with the parts 86 APPENDIX B FORMULAS THAT CAN BE USED FOR CNC PROGRAMMING In the table below there are formulas that can be utilized in CNC programming Table B 1 Formulas that can be Used for CNC Programming Too Raines amp Tool Radius sin E OR DS add d Hors a b asin E OR csc E b a c acos E OR id sec E a c a cos E OR sec E M 4 id vg E D i tan B E D l t F 0 5D 1 tan B X N F 99 100 H LSD tan B F 0 5D 1 tan B X N F Y ix a re TOOL RAD AX OFFSETS AT PTA AND PTS DUE TO ANGLE a x 5 t gt E i NES OCC z Mn EET CUTTER gt A F 1 S EE eod g TOOL PATH Rigi a AY Sax AX a tan YY AX ar A AY av tan 45 B AY ay tan 45 2 poo AY x JAX Nod Aa iL j AY i m b P 101 Table B 1 Formulas that can be Used for CNC Programming AX arc AY N 4 G ry Ai ry AY R4 rY Ai rY Aj APPENDIX C DRILLING AND MILLING OPERATIONS PROGRAM The following table shows the programming for drilling and milling operations done by CNCez software It also shows the data preparation for CNC programming Table C 1 Drilling and Milling Program Programming of DRILLING Operation 90 G00 Rapid Positioning 5 20 00 G20 Input in inch G90 Absolute programming CIEN e 5 MO6 Tool Change as Jro 03 M03 Spindleoncw
44. e Sensor 5T 59 vili TABLE OF CONTENTS Continued Chapter 45 Inspection MEIDOU eec uer eroi beoe n vase reped tede eode east si ute dd 4 0 Project Descriptio eese ta pe E ote dedic oven ebrii PROGRAMMABLE LOGIC CONTROLLERS eee ee UA S MElvire tere m TM SPEC Dev lt OS anena E E M malen cM er ane EC ep eeSs SE PLE COMPONCINS tT C L 5 4 PLC Computer Functions eeeeeeeeeeeeee 5 5 Advantases Of PEC 2c Did tieu tented ut aus esa e rape Eee P epu erii 5 6 Basic Logic Gates used in PLC AND OR and NOT sss 5 7 Case Study NJIT FMS mE 6 PETRI NET MODELING AND SIMULATION eeseeeeeeererereenenen 6 1 MEO GUC OM ia sesso sies ondes icu E HERR o Duy pd dena uc Nea eedidd 0 2 Petri Ner Del ttl ONS oos coool a Egon E OM Nes cd oru eee dota OO AN of ol Ag Seo IS ebd OOo Re E tuba EU teda aed 63 I Mathematical MOdels 2 uuo dicet retta ia eR BHO Me er earn ds 6 3 2 Applications ereeeeeeeee H nGeals 6 4 Modeling Methods nr 6 5 Case Study Modeling and Analysis of PN for NJIT FMS eesssss 6 5 1 Description and Modeline co en Eae Er e SEE Ro vio abet iut dede liM tet 0 5 2 ANIS etic accep E ieee enlaces eer o Deua roi ROM c3 08 Digan serene tore tere ER 6 7 Analysis of Ladder Logic LLD Diagram and PN
45. ed workpart CHAPTER 5 PROGRAMMABLE LOGIC CONTROLLERS 5 1 Introduction Today manufacturing becomes increasingly flexible and fully automated to achieve faster and better quality production and to stay on the competitive edge Programmable logic controllers PLCs are used in most industrial applications control They are considered as an integral and invaluable tool that helps designers and decision makers to better implement their long term manufacturing control plans by using computer hardware and software A PLC can be defined as a digitally operating electronic system designed for use in an industrial environment to implement specific functions such as sequencing timing counting and arithmetic control function and analog functions such as proportional integral derivative PID Ladder logic diagram LLD is used to program PLCs A Ladder Logic Diagram is a graphical programming language consists of a set of rungs each of which instructs the PLC to scan input s and activate output s A rung is bounded by two vertical lines representing the negative polarity on the left and positive polarity on the right Each rung describes the current flow from component s on the left side of the rung input s to the right side component s of the rung output s A PLC study is presented in this chapter Components of PLCs in Section 5 2 functions and advantages of PLCs in Sections 5 3 and 65 66 5 4 respectively and the basic logical gate
46. ell P Groover Industrial Robots Technology Programming and Applications McGraw Hill Book Company 1986 126 30 Patel Peasant A Tools fot the Design of Flexible Manufacturing Systems Master Thesis Dept of Electrical Engineering New Jersey Institute of Technology 1998 31 Prichard et al Solving scheduling problems using Petri nets and constrains logic programming Available at http www lisi ensma fr members richardp papers etfa95 pdf 32 Richard Scott Brink A Petri Net Design Simulation and Verification Tool Master Thesis Department of Computer Engineering Rochester Institute of Technology NY 1996 33 Staff of Automation and Management Systems Division Flexible Manufacturing Systems Handbook Noyes Publications Park Ridge NJ USA 1984 34 Warren Seams Computer Numerical Control Concepts and Programming Delmar Publishers 1995 35 Workspace Version 3 2 Reference Manual Revision 13 1994 36 Zhou M C and Venkatesh K Modeling simulation and control of flexible manufacturing systems World Scientific NJ 1999 37 Zhou M C and DiCesare F Petri net synthesis for discrete event control of manufacturing systems Kluwer Academic Publishers MA 1993
47. en axis movement into closely spaced points that can be identified by the controller e Accuracy the capacity of MCU to position the worktable at a desired location e Repeatability the ability of the control system to return to a given location that was previously programmed into the controller e Mechanical Errors results from gear backlash leadscrew play deflection of 16 17 machine components and similar inaccuracies in the mechanical positioning system 2 2 CNC Machine Classification CNC machines can be classified as shown in Figure 2 1 according to Y Mechanical systems Y Control systems Y Coordinate system Y Motion control v Number of axes Y Control loop system 18 CNC Machine Coordinate system Control system Control Loop System Floating Zero MCU Open Loop Closed Loop system yst System Motion Control of xes Contouring Straight Cut Five Axes Mechanical System Clamps and Fixture RPM F eed Geometry L etc Mechanical Drive Element Servomotot Feedback System Recalculating ball screw Mounting Ballnuts Figure 2 1 Classification of CNC machine 2 2 1 Mechanical Systems The mechanical system used in CNC machines consists of the following vital parts e Clamps and Fixture A Riveted fixture is used in CNC milling table it is two Perpendicular plates are fixed with rivets or threaded by screws It s very important to be precise in firming the fixture so a hydraulic motor is used to
48. ented in table 6 7 Table 6 8 shows the reachability tree for drilling station P23 tee TOS p22 N N 21 Pel Figure 6 5 Modeling for drilling station Table 6 7 Places Events and Transitions for Drilling Station Description Raw material available with a cart Drilling operation performed on the raw material Finished part available with a cart Drilling machine available Initiation of drilling operation Completion of drilling operation The PN modeling for the chamfering station GMF M1 robot and 100 tool crib is shown in Figure 6 6 and the description for the places and transitions is presented in table 6 9 Its reachability tree is presented in table 6 10 Figure 6 6 Modeling for chamfering station Table 6 9 Places Events and Transitions for Chamfering Station i 28 Loading machine with the part Process chamfering operation Unload part after operation is finished Part is available to be released to the system Unload tool after operation is finished GMF M Irobot ts available Chamfering machine center is available Are added to check this subnet for its properties 87 88 Table 6 10 Reachability Tree of PN Modeling for Chamfering Station GMF M1 Robot and a 100 Tool Crib P P ge G3 Uo Pb llr PREP Piel eetet EHEHE l l Figure 6 6 shows from left to right the modeling modification made to reduce the number of
49. ereereee 35 20 Case Study TOL NUTT EMIS cscsces oe ccanace otras eei a arte shd seid deese ud dosads 36 3 INDUSTRIAL ROBOTS AND INTERFACE WITH CAD SYSTEM 38 SNMP PN m T T eae 38 32 4 Proprammine Techniques te tessera tug bueno Ep EE EeQ aaa ites 30 9 2 ISODOD SONI W Ale cotidesieiee att dst inp M M ME ara SL E DU UA The DE LE US 30 DE JISODOE ANIO a euis boc tot apt eo pua edes seat Dres as 41 9 9 WOKS DACE S ses siete pe undis caduti do cu a Late ia tee tee rate toc Cdi 44 3 5 1 FeaT Si E ass TEE EN N T TA E E 44 3 9 2 2S DOCITIC LODS sasa n e Er a CER PR eME UE QUEE 45 319 9 APPCaAUONS speriene e Ein po Cet semet eo tuus Ded enden EEEE 45 3 6 Case Study Sample Program for Drilling Operation done by NJIT FMS 46 4 COMPUTER VISION INSPEC HON iib in a Eat ibo een ase 50 Gb A vire dier ERR RTT 50 42 Operations of Computer VISIO aiebat hen ee ha ao Donec RU een totus e Ue Ebene 51 4 2 1 Image Acquisition and Digitization eeeeeeeeeee 52 4 2 2 Image Processing and Analysis scesscccccccccccecececceececceeeeeeseeesenes 53 22 9 Interpretation oco ea duteb aeuum a uus 54 4 3 The Itran IVS Computer Vision System ccecccccceecceeeeesessssessesssesessseeees 56 4 5 1 Obfaming an mage eU aaa A etd iede uidens 57 4 3 2 Area LOIS 2 iibi Pee ree e Rate AMO a end E ioeLD os 57 4 3 3 Screen Messages RS232 Outputs and Discrete I O 59 4 4 The FS11 Featur
50. essing needed for recognition and interpretation More specifically the following topics are particularly central to what is published in the journal e Computational models of the human visual system e Early vision e Data structures and representations needed for high level vision e Shape representation and extraction 50 S1 e Range data analysis e Use of motion for recognition and interpretation e Matching and recognition e Architectures and languages for image processing e Vision systems 4 2 Operations of Computer Vision Computer vision inspection can be defined as a method of using a computer to analyze an image obtained from a video camera The operation of the vision system can be divided into the following three functions 27 l Image acquisition and digitization 2 Image processing and analysis 3 Interpretation These functions and their relations are illustrated schematically in Figure 4 1 1 Image acquisition and digttization Camera source Light EN Application 52 Image processing 3 Interpretation and analysis Computer LI Image processing interpretation T Agony _ Analysis Mains aM Decisions po i cc i actions Figure 4 1 Basic functions of a machine vision system 4 2 1 Image Acquisition and Digitization Image acquisition and digitization is accomplished using a video camera and digitizing system to store the image data for subseque
51. f TEMS LS AMETER INNER ENTUM RADIUS gt S f TOOL DH AMETER a b Figure 2 7 Tools which are used in a NASA II milling machine b drilling operation 23 2 2 2 Control System The control system consists of the following major parts machine control unit MCU data processing unit DPU and control loop unit CLU MCU consists of a microcomputer and other related control hardware that store the program of instructions and execute them by converting each command into mechanical action of the processing equipment e g machine tools one command of a time Figure 2 8 shows an MCU structure Memory Input output interface ROM Operation Central processing unit Operator panel system CPU Tape reader RAM Part programs Machine tool controls Sequence controls Position control Coolant Spindle speed control Fixture clamping Tool changer Figure 2 8 Configuration of CNC machine control unit The main functions of the DPU are to read the part program decode the part program statement process the decoded information and pass the information to the control loop unit CLU In addition it positions each axis of the machine tool and directs the motion of the axis the feed rate and cutting speed The functions of the CLU are to receive data from the DPU convert the data to control signals operate the drive mechanisms of the machine receive feedback signals about
52. f Olivetti Machining Center Oana O Only if the last line of execution program 1s performed The chamfering program 1s executed Only if the part is there And the clamps are closed S X se Port 000000 0000000 0000000 116 Table F 1 Sequences Description for PLC Control Program Continued And the robot is at position out of chamfering working Note tool is changed according to the chamfering program so once the program is scanned and there is a tool change it send signal to the robot to grip the specified tool from 100 tool ripper and fix it in the Olivetti Machining center Cart moves to the transporter Only If the chamfering is done And the robot execution program of returning back the part to the cart is done APPENDIX G LADDER LOGIC DIAGRAM FOR NJIT FMS The following figures show the ladder logic diagram used in GE series controller The ports names consist of one or two letters followed by four digits as determined by manufacturer 00490 10022 Lee ent id ADOI01 ADOlll ADOL S T 414 400051 004900 AO0049 AD0130 E 00015 00480 I004 00089 ff _ Ao0039 10021 00490 10020 00014 10018 1006 00050 00490 A005 400205 AD Timer T 4 sec T0006 R0137 00490 ADRS 00049 00190 00199 00191 00199 00400 Canter C 4 00490 R0132 R 00430 00400 00001 00490 ADO200 AQO0104 lt a DO ME PETA 00490 00002 A0010 00004 400100 E 00015 aei 00014 To0Q
53. f manufacturing New control and modeling techniques are always sought for the purpose of achieving further improvements A technique that has the potential for generating additional improvements is the use of Petri nets The focus of this chapter is primarily on Petri nets PN and their contribution to industry development Definitions are discussed in section 6 2 classifications of PN in section 6 3 modeling methods in section 6 4 a case study of NJIT FMS in section 6 5 and finally the connection between Petri Nets and PLC in the last two sections 74 75 6 2 Petri Net Definitions Petri Net A Petri net is a graphical and mathematical modeling tool which is able to model concurrent asynchronous distributed and parallel systems The basic Petri net consists of four different components Places Transitions Arcs and Tokens Place A Place is a basic Petr net component which represents a condition and represented by a circle If a place is a member of the input function of a transition it 1s a precondition for that transition or event to occur If a place is a member of the output function of a transition it is a postceondition of that transition Transition A transition is a basic Petri net component which represents an event The event may occur when all of the input places to the transition contain enough tokens to enable the input arcs to the transition The occurrence of the event also known as a firing of the transition wi
54. g image brush thresholds Figure 4 5 a dialog box displays a histogram of the image in this box lower and upper thresholds can be updated to show the qualifying pixels The histogram is a vertical bar chart set on a horizontal axis of 63 gray scale values The height of each bar shows the relative number of pixels at each gray scale Value For example if the bar over the gray scale value 33 is twice as high as the bar over the gray scale value 32 then there are twice as many pixels in the region with gray scale value of 33 as there are with a value of 32 64 aunces ualEllBs b tai 4 170 0 1 ee 373 84 t p arde p m et EE ey ne 4E s 309 003 dee d O ROS DOO 0 lower 4 a gt upper Ay Figure 4 5 Tooth brush threshold 4 6 Project Description The IVS system was configured to identify NJIT FMS which is fabricated on the NASA II CNC milling machine and shown in Figure 4 6 The IVS system scans the part as it passed the lens and matches its image with qualifying logical expressions that were created for each part Screen messages were displayed for the identification of each block accordingly Using the RS232 input of the IVS system a terminal software program using windows software was used to display and store the inspection data for each NJIT FMS work part make comparison with a predefined image and energize the robot to place each part the accepted or rejected bins Figure 4 6 model of the inspect
55. he CNC milling machine The NASA II CNC milling machine performs the etching of NJIT FMS on the upper surface of the part The GE P 50 robot picks up the completed part from the milling machine and loads it back onto the fixture on the cart The Vision system inspects the completed part to determine the acceptance or rejection of the part eThe GE P 50 robot then picks up the completed part and places it in the acceptance or rejection bin CHAPTER 2 COMPUTER NUMERICAL CONTROL 2 1 Introduction The evolution of this field could not have been possible without the existence and availability of computers especially mini or personal computers The most important application of computers was in the development of the control operations in the conventional machines industry such as cutting welding lathing and milling Computer use in metalworking machines aids in controlling and performing complex and precise machining operations at a low cost Sections 2 2 and 2 3 contain CNC classifications Section 2 4 discusses numerical control NC CNC and direct numerical control DNC Section 2 5 shows details about NC part programming and Section 2 6 describes some data used in CNC programming Finally there are examples for CNC programming for the case study in NJIT FMS presented in Section 2 7 The following terms are used CNC operations 27 e Control Resolution the capability of machine control unit MCU to divide the range of a giv
56. he way to understand such a control system is to determine how it is designed and then investigate its hierarchical structure Figure 1 2 is an example that gives a comprehensive understanding of how such systems work There are three levels which are shown the higher level contains the host computer the middle one contains the client computers and the lower level contains all the devices controlled by the clients such as CNC controller material handling system controller controller for AS RS vision controller robot controller In addition the functions performed within the FMS hierarchy are shown in Figure 1 3 In this figure there is a business computer which is not primary level and its basic function is to record and schedule the production and it can be separate The functions of other components shown in figure below are shown in Figure 1 3 Host Computer Client Client Client Client Client Computer Computer Computer Computer Computer CNC CNC CNC m CNC Machine Vision System Tool CNC Machine AS RS Industrial Robot Tool Material Handling Device Controller Figure 1 2 Hierarchical structure of FMS Buisness Computer Production Record Production Schedule CNC Dat Production Schedule Host Computer Data Management Production Record Gathenng 4 ta Modfication Schedule Running 5 iy Sede Dd Interactive Falur Diagnosis s A Heise CNC Data Matenal Handling Control
57. if system not yet enabled AQOOSO and transfer Tables not in end positions LS 14 LS14A LS 20 LS 20A pe AO0051 LL Latched if normal sto ched 1f normal s REA OOOLS after 8 parts Emergency Stop Sorin ae D RENS o 1 System Enabled p Energized if System Run input Note i e not Emergency Stop and transfer O0490 tables located at the end positions They should 10021 be Home if they carry no cart and away if they carry A cart Initial Inspection Station 1 Seq No Release cart from load unload station Side SURE Only if cart present and no cart at inspect LS 6 1 00014 STAT 45 625 110 Table F 1 Sequences Description for PLC Control Program Continued Energized transfer table 1 tube drives Home Only if conveyor initialized SBE 2 gt And no cart on transporter RGIS 14 Latched 3 sec After hitting home limit lt LS 14 gt switch 15 Cart present at queue 3 no ees x Latched 1 5 sec after having hit No second cart will be able to enter the queue mechanic stop lt LS 105 oe Activate enter Push Pull solenoid only if Transfer table home LS 14 amt and cart present OR no cart entered L5 I02 PC SEES and not drive till home and not normal stop OR not O0001 already running actuator at queue 3 on rear conveyor receives air flow to push mechanical stop aside only if lt LS14 gt lt SEE 16 gt lt LS 10 gt lt SE
58. in off line programming which means that it can prepare the program and download it to the robot without interrupting production The features specifications and applications of Workspace 3 are discussed below 3 5 1 Features Workspace 3 is a 3D graphical simulation software system for robotics and mechanisms It is a productive tool designed to make the implementation of advanced manufacturing systems as simple and economical as possible Workspace increases productivity and reduces time 34 The features are 1 Quickly model work cell layout 2 Demonstrate process and plant design 3 Prepare real time animation for presentation 4 3D CAD system constructive solid geometry 3 5 2 Specifications 1 Teach point files 2 l 2 Graphical representation results Ability to easily off line programming Kinematics modeler 3 5 3 Applications L 2 3 4 3 Table 3 1 is an example of controlling the robot motion using Workspace 3 It describes Arc and spot welding Materials handling Paint spray Palletizing Electronics assembly 45 the joints and points positions for the SCARA industrial robot for a drilling operation Initially after the robot is built the joints have home position values in the X Y and Z axes as X 708 Y 2 and Z 204 and the values of rotational axes a b and c around each axis are a 0 b 0 and c 0 if the joint is taught to move the point then the coordi
59. ion X1 and loads it into the fixture located on the CNC machine table 2 Once the part is loaded on the CNC milling machine the robot retracts and the milling machine mills the rectangular part as required 3 After the milling machine operation the robot moves to the milling machine to remove the part that was machined from the holding fixture 4 The robot returns the finished part to the same cart on the conveyor State 5 Vision Inspection 1 A signal is sent to the vision camera to inspect the part 2 The vision system analyzes the part and outputs a signal that directs the PLC to tell the robot to accept or reject the part 73 3 The robot runs either an accept program to place the part in the accept bin or runs a reject program to place the part in the reject bin The entire operation with its control points is shown in Figure 5 5 For more information about the PLC LLD used to control NJIT FMS cell refer to appendices E F and G GE Series 6 Power Control PB 321 Rosca Control Panel a T fer 1 Center Machine T fer ransfer ransfer E Queue amp Queue 2 Robot Queue 3 gt o gt e ae qe de LG lie A X Part Feeder E od Figure 5 5 Control points of NJIT FMS operation CHAPTER 6 PETRI NET MODELING AND SIMULATION 6 1 Introduction the use of technology and the application of control and management theories and techniques have revolutionized the flexibility o
60. it is given the binary value of white e g 1 If the value is less than the defined threshold it is given the bit value of black e g 0 Another segmentation technique is edge detection It determines the location of boundaries between an object and its surroundings in an image This is accomplished by identifying the contrast in light intensity that exists between adjacent pixels at the borders of the object 4 2 3 Interpretation The interpretation function is usually concerned with recognizing the object a task termed object recognition or pattern recognition The objective of this task is to identify the object in the image by comparing it to predefined models or standard values Two commonly used techniques are template matching and feature weighting The most basic template matching technique is one in which the image is compared pixel by pixel with a corresponding computer model Within certain statistical tolerance the computer determines whether or not the image matches the template Several examples of this are shown in Figure 4 3 352 Automotive Automotive Gold Fingers Figure 4 3 Diverse applications for which machine vision has been implemented The process begins with an image that is formed from a camera lens using a camera receiver The receiver is a CCD charged coupled device array which converts the image into a grid of separate points called pixels The pixels are seen as squares on the grid Each pixe
61. l is light sensitive and therefore has an electronic charge which is representative of the amount of light the lens projects onto them The electronic signals are sent to a processor where an analog to digital converter coverts the signals into a series of binary numbers and stores them into memory Each pixel is therefore assigned a numerical value that represents a particular intensity of light The light intensity number corresponds to a grayscale indicator that uses values from O to 63 0 begin black and 63 begin white Intelligent Visual Sensor IVS systems can analyze the converted image in a number of ways IVS use algorithms that can identify measurements edge detection part defects and other parameters These algorithms can be used simultaneously to detect 56 acceptable and rejectable parts During an inspection the system could use a triggering device such as a photoelectric sensor to enable the camera to acquire an image of the object that is being inspected The image would then be converted to a digital array and stored into a buffer The vision system could apply an algorithm such as counting edge pixels and comparing them to a standard value for this measurement The values generated can be used to calculate other functions within the IVS system before sending an output through RS232 comedo to an external device such as a programmable logic controller 4 3 The Itran IVS Computer Vision System The IVS system used for the
62. language The software used to control this system is SensorEdit v2 1c with many menus to help the user to get the best control of inspection It is shown in Figure 1 8 with the whole set contained in this system The Itran computerized vision system inspects the part and decides if the part meets the specifications of the control algorithms A signal is sent to the PLC in a special format so that the robot can be ordered to place the part in the acceptance or rejection bin 22 J Figure 1 8 TRAN Computer vision system 10 1 5 2 Robots e IBM 7535 Robot This robot is a SCARA type point to point robot that 1s interfaced with the FMS using a photoelectric sensor fixed to the conveyor system Its specifications are 5 degrees of freedom 4 axis control payload up to 30 pounds and repeatability of 0 005 with DC servo drive Its configuration is shown in Figure 1 9 Figure 1 9 IBM 7535 robot e General Electric P 50 Robot The specifications of this robot are 5 degrees of freedom 5 axis robot payload of up to 22 pounds and repeatability of 0 008 It is used in the automobile industry for spot welding applications and is used in this FMS as a material handling robot with hydraulic drive and a jointed arm configuration Figure 1 10 below shows the GE P 50 robot 11 Figure 1 10 General Electric P 50 robot e GME MI Robot The GMF MI robot specifications are 6 degrees of freedom 4 axis robot payload up to 44 pounds
63. ling operation by moving the drill only up and down in vertical direction This robot consists of number joint and links It has five degrees of freedom with three types of joints orthogonal rotational and revolving In orthogonal joint The relative movement between the input link and the 42 output link is a linear sliding motion The input and the output links are perpendicular to each other It is called O joint and is shown in Figure 3 2a Rotational joint provides a rotational relative motion of the joints with the axis of rotation perpendicular to the axis of the input and output links It is called R joint and is shown in Figure 3 2b In revolving joint The axis of the input link is parallel to the of rotation of the joint and the axis of the output link is perpendicular to the axis of rotation It is called V join and shown in Figure 3 2c output PHONE Ere 5 input A output m A Figure 3 2a Orthogonal joint Figure 3 2b Rotational joint put D Figure 3 2c Revolving joint M output GE P 50 Robot The GE P 50 robot was shown in Figure 1 10 has a vacuum gripper to enable picking up depositing a block from to the cart It has a jointed arm configuration with the arm being able to swivel about the base This robot consists of rotational joints and twisting joints The rotational joint allows for a rotational motion of the links with the axis of rotation perpendicular to the axis of the input and output links
64. ll ccecceccccecceceeeeeeeeeeeeneeeees xlv 66 67 70 71 73 77 78 82 84 86 87 89 91 94 95 96 97 98 119 CHAPTER 1 FLEXIBLE MANUFACTURING SYSTEMS 1 1 Introduction Automation is a technology concerned with the application of mechanical electronic and computer based systems used to operate and cone production systems One of the most important types of automation is flexible automation Productivity cost quality and utilization are concepts of concern in most industries Flexible manufacturing systems FMS can promote the integration of these concepts and many more which are important to the manufacturer for example 27 e Flexibility e Group technology e CNC machine tools e Automated material handling between machines e Computer control of machines Flexible manufacturing system can be defined as follows A Flexible manufacturing system consists of a group of processing stations predominantly CNC machine tools interconnected by means of an automated material handling and storage system and controlled by an integrated computer system 27 In addition a flexible manufacturing system can be defined as a computer controlled configuration of semi independent work stations and a material handling system designed to efficiently manufacture more than one part number at low to medium volumes 32 In this Chapter the focus will be on data flow and hierarchy of FMS in Sections 1 2 and 1 3 respectively com
65. ll result in tokens being deposited through each of the output arcs of the transition into the respective output places Arc An arc is a Petri net component which relates places to transitions and transitions to places and has an associated weight representing the number of tokens needed to enable the arc Token A token is a basic Petri net component which is thought of as residing in a place A token signifies that a particular place or condition is true Multiple tokens residing in a place are usually representative of the existence of multiple resources Reachability Tree A reachability tree represents all of the obtainable markings for a Petri net The tree begins with the initial marking with a line from the initial marking to a new marking for each enabled transition Marking A mapping of tokens to places which defines a state for the Petri net 716 Live A Petri net is live when there exist no terminal nodes in the net s reachability tree For each marking in the reachability tree there exists at least one transition that is enabled for that marking Safe A place is said to be safe if for all possible markings the number of tokens in that place never exceeds one The Petri net is declared safe if all of the places in the net are safe Bounded A place is k bounded when for each marking in a reachability tree the maximum number of tokens appearing in that place never exceeds k A Petri net is j bounded if all place
66. m each input place of the transition and adding one token to each output place of the transition The enabling and firing rules are illustrated in Figure 6 2 The above rules can be explained in detail using the Petri net example shown in Figure 6 1 It consists of four places and three transitions initially M 1 0 1 0 so for tl to be enabled it should have two tokens one from P1 and another from P3 Both tokens are available in this example so the firing takes a place and the token moves to P2 meaning that processing is activated Transition t2 has one input and two outputs so once the token is in P2 automatically t2 has been enabled and the token moves to places P3 and P4 In this state t1 is not enabled because it doesn t have a token in P1 while t3 1s enabled So P4 fires the token to P1 and process recycles it self Figure 6 2 shows every enabled transition and their firing places Table 6 1 describes the reachability tree for this Petri net Processing Avalability Figure 6 2 Transition of tokens which is based on enabling and firing rules 79 Table 6 1 Reachability Tree for Figure 6 2 6 3 2 Applications Petri nets can be used in the following applications Manufacturing production and scheduling systems gt For sequence control both modeling and visualization and generating the code for a PLC Communication protocols and networks gt An alternative to finite state machines and s
67. mizes the time a robot must be taken out of production in order to accomplish the programming A PC based CAD system interfaced with an industrial robot is beneficial over the standard robot programming techniques since robot programs can be generated automatically by a set of graphical instructions displayed on the computer screen Once proper kinematics and geometries are established a graphical simulation of the workcell s function will occur in real time allowing for modification and improvement before generated programs are downloaded into the robot s controller 3 3 Robot Software A robotic McDonald Douglas CAD software system consists of four modules namely PLACE BUILD COMMAND and ADJUST The relationship among these modules is shown in Figure 3 1 40 Part Modules Robot Library p Cell Module Collision NUNC Cycle Time Andyss Option Translation COMMAND Input from Guidlines Pre Pro cessing Actual Cell Locational ADJUST Inform ation TRANSLATOR Robot Program Figure 3 1 Process flow from simulation to translation The PLACE Positioner Layout And Cell Evaluator module is used to develop a model of the workcell similar to the actual working system It is also useful in simulating all the operations of the FMS cell on the system so that the various layouts and motion sequences can be animated and evaluated The BUILD module enables the user to graphically build any additional robots or other devices that are
68. nates will be changed and the new points called TP1 its values are shown in the table below So there are four teach points to perform drilling operation done by the IBM 7535 robot 46 Table 3 1 Coordinates of the Points with Joints Motions of IBM 7535Robot z 0 21 LO NON REND QN BIA Y QN SJ v Ja K o V NI DIN SS Ajo bho N pand N t2 p MO io bo E t2 O 3 6 Case Study Sample Program for Drilling Operation done by NJIT FMS The program presented here shows how WorkSpace 3 can be used to program the IBM 7535 It also shows the parameters which should be considered in the programming To understand this program the following definitions are needed e Karel 2 The language for the simulation and for writing this program e Teachpoint TP The point where the joint should rest by the end of the movement e Position The defined position for each teachpoint e NullObject Hidden object used to join two objects e AttachObject A command likes the same but to attach the block to the cart Referring to the Figure 3 5 If the yellow bar rotates about the X axis by o degrees the transformation matrix for that rotation is Rot X P Similarly if the rotation 47 takes a place around Y axis or Z axis the rotation matrices are Rot Y D and Rot Z D respectively These matrices are shown below 0 0 0 cos 0 sin O QO cos sin O 0 l 0 0 Rot X
69. nt analysis The camera is focused on the workpart and an image is obtained by dividing the viewing area into a matrix of discrete picture elements Pixels in which each element has a value that is proportional to the light intensity of that portion of the scene The intensity value for each pixel is converted into its equivalent digital value The operation of viewing a scene consisting of a simple object is depicted in Figure 4 2 53 a ib Figure 4 2 Dividing the image into a matrix of picture elements where each element has a light intensity value corresponding to that portion of the image 4 2 2 Image Processing and Analysis The amount of data that must be processed and analyzed is significant The data for each frame must be analyzed within the time required to complete one scan 1 30 sec A number of techniques have been developed for analyzing the image data in a vision system The segmentation technique is used to define and separate regions of interest within the image Feature extraction methods are used to determine the features e g length width or diameter based on the object s area and its boundaries 54 There are two commonly used segmentation techniques The threshold technique which involves the conversion of each pixel intensity level into a binary value This is done by comparing the intensity value of each pixel with a defined threshold value If the pixel value is greater than the threshold
70. ntroller As shown in Figure 2 2 widely used languages are Automatically Programmed Tools APT and COMPACT II The main tasks of the programmer are to defining the geometry of the work part and to specifying the tool path and operation sequence dk rammer Definc part geometry Define tool path and Define tool path and 2h E E operation sequence operation sequence Computers vut qan dan on Anthmetic and cutter Editing Job offset computations phase Figure 2 20 Tasks in computer assisted programming 2 4 4 NC Part Programming Using CAD CAM In this programming the part program is directly prepared from the CAD part geometry either by using NC programming commands included in the CAD CAM system or passing the CAD geometry into a dedicated CAM program CAD CAM systems provide facilities to display the programmed motion of the cutter with respect to the workpiece which allows visual verification of the program and 35 the ability to edit interactively a tool path with the addition of tool moves standard cycles and perhaps APT macros or the equivalent from other languages 2 5 Data Preparation for Numerical Control A post processor is used to convert the machine independent code format into a format suitable for the machine tool machine control data MCD The machine receives instructions as a sequence of blocks containing commands to set machine operations parameters dimensional and speed data The classification of iden
71. or a unique family of robots Recently software have been developed that are compatible with the robots of any manufacturer The price of the package 1s affected by the complexity of its programming For example there are packages that cost 25000 or more like the PLACE graphic simulator The software used one in this chapter is Workspace 3 and works in the DOS environment There are new versions of this software such as Workspace 5 which works in Windows Workspace 3 is an off line programming graphical robot simulator that offers accuracy and compatibility regardless of what major manufacturers robot is used The benefit of Workspace 3 is that it helps to visualize of the robot process quickly before it goes into the production stage 38 39 3 2 Programming Techniques Robots are programmed using manual setups leadthrough programming computer like robot programming languages and off line programming Manual setup techniques are usually associated with limited sequence robots where limit switches and mechanical stops provide robot control Leadthrough programming involves teaching a particular task by moving the robot s manipulator through a sequence of motions and recording the position coordinates Computer like robot languages involve a specific set of instructions that provide robot control from a simulated CAD model Off line programming is accomplished by sending a set of instructions to the robot controller This mini
72. ponents of FMS in Section 1 4 facility layout in Section 1 5 and product cycle in Section 1 6 1 2 Data Flow of FMS It is important to analyze the data flow of the system and to define the function of each module in the system The operation of an FMS can be treated as a sequence of events which can be done concurrently or in series whereby one event can trigger the occurrence of another event It can be seen from the Figure 1 1 how the data flow between elements contributes in FMS and also it can be noted that the response of the system is Y Retrieving a new work piece from a storage place Y Loading unloading a work piece a robot Y Loading unloading tools to the machines by robots Y Accepting rejecting machined parts during the inspection stage Y Controlling the fixtures and clamps Y Controlling the material handling systems such as carts transporters and AGV s Y Monitoring the conditions of the machine and cutting tool to save the machine from damage The system takes care of all procedures until all operations are finished according to the production schedule Materials Products Nac hire Process Staton Tool Monitor Control hfesbreak NC Automatic Tool Pro Change gramming Toold Setting Data Figure 1 1 Data flow of FMS ocification l L 1 3 Hierarchical Structure of an FMS Control System Typically the computer control of an FMS is complicated and t
73. porter 1 tube drive reverse direction Transporter 1 traffic Q solenoid Work station 1 solenoid Work station 2 solenoid Enter transporter 2 solenoid Exit transporter 2 solenoid Transporter 2 tube drive forward direction Transporter 2 tube drive reverse direction Transporter 2 traffic Q solenoid Load unload solenoid System normal stop Robot gripper solenoid I O Ports O0003 O0004 0 o JE Q 00011 00012 00013 00015 00016 Q 2g o Q S P 108 Nickname SOL331 SOL332 MSF334 MSR334 SOL337 SOL340 SOL343 SOL431 SOL432 MSF433 MSR434 SOL437 SOL440 STOP Gripper ON 2 CNC Milling Station DESCRIPTION Machine tool vise solenoid _ Machine tool emergency stop Machine tool feedhold Machine tool cycle stop Machine tool cycle start Machine tool MOI Optomation system reset JE I O Ports Nickname Vise Closed Emergency Feedhold Sysstrt A Vision Inspection Station DESCRIPTION Car present workstation 1 take picture camera 1 Reset take picture station 1 I O Ports O0049 O0050 Nickname PRTPR2 z as 4 Robot DESCRIPTION Robot input 0 Cart present at work station 2 Robot input 1 Robot input 2 I O Ports 00065 00066 00067 Nickname Go get Part 109 Table E 1 Input List Continued Robot input 3 Robot input 4 Robot input 5 Robot input 6 Robot input 7 2 Robot input 8 Accept reject Robot input 9 Ro
74. push the block to the 19 clamps Generally the setup of the fixture is the most time consuming process which requires tool making skills to design the proper features for ultimate matching stability e Mechanical Drive Elements Consist of a servomotor a feedback system and recalculating ball screws consisting of ballscrews and a mounting ballnut Servomotor A servomotor shown in Figure 2 2 is an electromechanical device in which electrical input determines the position of the armature of a motor and the rotation of the shaft moves the table forward or backward They are used extensively in robotics and radio controlled cars CNC machines airplanes and boats Figure 2 2 Servomotors Feedback system The function of the feedback system is to assure that the table and workpart have been properly located with respect to the tool It could be triggered by analog sensors such as synchros revolvers and linear inductive scales or digital sensors such as binary encoders rotary pulsers linear optical scales and laser interferometers Figure 2 3 shows some example sensors 20 Secondary 2 Primary Secondary 2 Lead Wires h O10oo f Displacement E Moveable Core a b c d e Figure 2 3 a Resolver b Synchros c Inductive linear scales d Binary encoders and e Laser interferometer Ballscrews A ballscrew shown in Figure 2 4 and 2 5 is a mechanical device that replaces the sliding
75. put device The next rung describes a logic AND gate To energize output O 6 2 both input switches or devices should be energized The third rung describes a logic OR gate Output O 6 6 can be activated if either one of inputs I 2 4 or 6 12 or both should be pressed The following rung describes the latching concept in PLC programming Once the switch I 2 4 is pressed or activated the circuit is closed and output O 5 1 is energized It will remain on irrespective of whether the previous switch is off or on The function of switch I 1 2 is to let the current flow through the circuit for the first time and to cut off the circuit whenever is needed it might be used as emergency switch 70 The fifth rung shows a timer element When switch I 2 2 is pressed the output goes on and the timer starts timing for four seconds When the timing is over output O 6 12 goes off and the timer sends a signal to the following rung to activate output O 6 4 Bl O6 T i 1 1 2 I2 O6 1 6 2 r2 O 6 4 6 If 12 I2 I O S 4 1 85 I2 l Q 6 2 12 TON Timer 4 0 Tine Base 1 0 3 Preset 40 Accum 0 C O 6 E 7 I C50 SS 1 rese Figure 5 4 An example for LLD programming The seventh rung shows counter element Here after the switch I 1 3 senses something 5 times the counter sends a signal to the following rung to activate it and output O 6 7 71 goes on To reset the counter a different input switch should be used as shown in the las
76. puter Numerical Control Direct Numerical Control An NC machine uses a tape reader to deliver the part program to the MCU The MCU has storage capacity and can process only one command at a time 2 3 1 Digital Computer for NC Digital computers in NC can be done through Incorporating 1 Direct numerical control 2 Distributed numerical control 30 2 3 2 Direct Numerical Control DNC Direct Numerical Control is sed when computer is used to control several machines simultaneously This type of control was implemented first in the late 1960s Instead of using a punched tape reader to enter the part program into the MCU the program was transmitted to the MCU directly from the computer one block of instructions at a time This mode of operation was referred as BTR behind the tape reader Direct numerical control consists of four components classified as central computer bulk memory at the central computer site set of controlled machines and telecommunication lines to connect the machines to the central computer These components are shown in the Figure 2 18 Central Bulk memory computer NC programs Telecommunication lines ME Tape 4 T pu reader ut 3 Figure 2 17 General configuration of a DNC systems Connection to MCU is behind the tape reader Machine tool Advantages of a DNC Y High reliability of central computer compared with individual hard wired MCUs Y Elimination of the tape and tape reader
77. r interfacing with material handling system e Flexible Measurements can be made along any line or contour e Visual feed back provided for operators RGB monochrome RS170 monitor output Real time display of images and vision tool graphics Screen message reports results e Meet special application needs Sensor development kit allows tailoring the sensor to meet specific application demands 4 5 Inspection Method In the SensorEdit program there is a Method menu which contains the methods used to control the computer vision system regarding the acceptance or rejection the inspected part Several options are available on the this menu as indicated below 63 1 Sum gray values Sum the gray scale values of all pixels in the tool Suppose there are four pixels in the tool having gray scale values of 20 23 24 and 26 This function returns a value of 93 2 Count threshold pixels Counts all pixels with gray scale intensity values equal to or above the threshold that has been set 3 Count pixels below threshold Counts all pixels with gray scale intensity values below the threshold that has been set 4 Sum edge energy Sums the edge strength values of all pixels in the tool 5 Count edge pixels Counts the pixels with edge strength values equal to or above the threshold The focus will be Count threshold pixels Counts pixels below threshold and Count edge pixels Changes can be done to the threshold values by selectin
78. rank Nanfara Tony Uccello and Derek Murphy The CNC Workbook Addison Wesley Publishing Company Inc 1995 6 Dr Herli Surjanhata Department of Mechanical Engineering New Jersey Institute of Technology Computer Aided Design Class Spring 200 7 Dynamic Modeling and Control Applications in Computer Integrated Manufacturing 1 Dec 1999 available at http www me iastate edu me522 f99 new ME522Modeling amp controlf99 8 Grand Valley State University Claymore Available at http clavmore engineer gvsu edu 1ackh eod mechtron mechtron 50 htmlZpefld 46556 9 ROTON Co Ballscrews and Ballnuts available at http www roton conyballs jsp figure2 10 MicroSystemsGeorgia CNC Programming available at http microsystemsgeorgia com cnc htm 11 BlueLeaf Ltd http www blueleaf co uk colour htm 12 Kennedy Space Center KSC Programmable Logic Controller available at http www hq nasa gov office codeq mtecpage ops05 pdf 13 Ian G Warnock Programmable Controllers Operation and Application Prentice Hall International UK Ltd 1988 124 125 14 ITRAN Corporation Feature Sensor User Manual 1991 15 ITRAN Corporation SensorEdit User Manual 1991 16 James Madison CNC Machining Handbook Industrial Press Inc NY 1996 17 Jan Sheau Jo The Impact of FMS on batch Production Processes Master Thesis IE dept NJIT 1986 18 Jon Stenerson Fundamental
79. rests between Robotics and CAD A broad understanding of the principles of CAD and robotics interfacing can be achieved from this tutorial It is about creating small robot structure using Worksape 3 S MINE Create cylinder create menu use default name radius 100 default length and region create box create menu use name link1 length 40 length2 400 length3 40 click on the front view icon click on the move object icon drag LINKI using the mouse with the mouse button pressed down to just above CYLINDER and move a little to the left so that rightmost part of LINK1 is just to the right of the center of the CULINDER click on the copy object icon use the default name LINK2 click on the move object icon and drag LINK2 to just above LINK so that the rightmost part of LINK2 is just to the right of the leftmost part of LINK1 click the mouse over the CYLINDER and then click on the snap onto object icon the flesh of the robot is now modeled and the base of the robot is highlighted create robot create icon enter 2 for the number of joints click on the top view icon the direction of the rotation of the first joint is shown as an arrow leave this joint in its default position click the mouse over LINK and then click on the snap onto object icon move Axis Edit joint submenu of the layout menu drag the axis using the mouse with the mouse button pressed down to the intersection of LINK1 and LINK 2 click the mouse over LI
80. ring control 2 2 5 Number of Axes In machine tools the cutter may typically move in multiple directions with respect to the workpiece or vice versa Therefore the controller may drive more than one machine axis In table 2 1 a classification of machines is presented on the basis of their number of axes and Figure 2 15 shows some machines with their number and direction of axes Table 2 1 Classification for the Number of Axes of CNC Machines Generally in two orthogonal directions in a plane e g lathe punch presses flame and plasma arc Two axes machines cloth cutting machines electronic component insertion And some drilling machines Machine tool controller is able to control the tool along only two axes simultaneously The machine movements are in planes parallel to Two and one half axes machines the x y plane Moves in the Z direction are drilling or for in feed or cutter retraction The movements are generally along the three principal directions x y and z e g milling boring drilling and coordinate measuring machine The tool can be moved along any curve by simultaneous control of the three axes but the tool orientation does not change with tool motion Three axes machines Typically the movements are three linear and one rotary axis e g lathe fitted with supplementary milling heads Normally involve three x y and z axes with Five axes machines rotation about two of these normally x an
81. s at station 2 L5 21 gt O0065 a Accept rej vart lt LATCHED gt 00073 lt SEE38 gt lt SEE38 gt T a aes SEX aaa penser 2 with ied from robot controller Manually with gt gt ee oo 04 SEND I Select job load CNC O0211 O0081 O0083 32 Latch if not job select 0 2 3 SEE2T O0084 And job select lt SEE 27 gt O0082 Unlatch if not power up Se e cee 114 Table F 1 Sequences Description for PLC Control Program Continued SS PRR DR SSS 5 SERA Qu RES jdm SES 1 Select job unload CNC 33 Unlatch M I lj Mark Century 1 Interface i Seq No In case di emergency stop PB 4 send O0033 Unstop signal to machine tool Robot clear of CNC Pees Se 600 Latch if robot sends Clear signal to 10068 PG 34 Unlatch reset 1f machine tool send load signal Resulting in output AOO0151 One shot Start permit for machine tool i 10034 not until robot is clear again ALL OF THE ABOVE NS 35 Machine tool start plus lt LATCHED Energized after start signal was energized and subsequently delayed for l 3 Sec Conditions for start signal AOO137 to be energized E Li Svstem enabled SEE 5 And Freehold NS O0034 As long as robot clear and no load unload request _and machine vise closed given by robot NS O0017 and CNC not in ah mode given by NS 10033 gt AO0137 OR after new system start 10
82. s in the net are bounded and j represents the maximum bound value of all places in the net k represents maximum number of tokens in specific place Conservative A Petri net is said to be strictly conservative if for all possible markings the total number of tokens in the Petri net always remains constant A Petri net may also be conservative with respect to a weighting vector such that all markings when multiplied by the weighting vector are equal 31 amp 35 6 3 Petri Nets Petri net models can be either mathematical or applications 6 3 1 Mathematical Models A Petri net is four pillars PN P T I O P a finite set of places P1 P2 Pn T a finite set of transitions ti 6 t Lan input function TxP gt 1 0 O an output function TxP gt 0 1 Ma an initial marking P gt N where N 0 1 2 lt P T I O M a marked Petri net T To start analyzing the PN assume the process shown in Figure 6 1 Processing Unloading Processing Availability t3 Figure 6 1 An example of processing which analyzes the mathematical modeling of a PN Where P P1 P2 P3 P4 T ft1 t2 t3 P1 P2 P3 P4 t1 1 0 1 O0 tl t2 0 1 0 0 O t2 t3 0 0 O t3 Mo A 1 0 1 0 P P2 P3 P4 0 1 0 0 0 0 1 1 1 O 0 9 Enabling Rule A transition is enabled if every input place contains at least one token 78 Firing Rule The firing of an enabled transition occurs by removing one token fro
83. s of PLCs in Section 5 5 The case study for the PLC used in NJIT FMS is presented in Section 5 6 5 2 PLC Devices State of the art PLC devices are used as controllers in assembly lines robots and other manufacturing facilities that facilitate precise control measurements Those devices can be digital or analog and used as inputs to the system or outputs from the system Examples of devices used with PLC are listed in table 5 1 and examples for the input devices used in NJIT FMS are shown in Figure 5 1 Table 5 1 Input and Output PLC Devices Input Devices _ Output Devices Limit switch Motor Photo detector Alarm buzzer Solenoid a b c Figure 5 1 Examples for input and out devices a Limit Switch b Photo detector c Solenoid 67 5 3 PLC Components A PLC has the following components 1 Input module 2 Output Module 3 Processor 4 Memory 5 Power Supply 6 Programmable Device The components of a PLC controller and their functions are shown in Figure 5 2 Provide connection between the programmer and the PLC Take signals tromthe processor and translates theminto forms that are appropriate to produce control actions by external devices Detachable Programming Device Typically 1145Vac used to drive the PLC Outputs Receive and convert the field stgnals into a form that can be used by CPU Look at the
84. s of Programmable Logic Controllers Sensors and Communications Prentice Hall Inc Englewood Cliffs NJ 1999 19 John W Webb and Ronald A Reis Programmable Logic Controllers Principles and Applications Prentice Hall Inc Englewood Cliffs NJ 1999 20 McDermott K J Zhou M C and P A Pate Petri Net Synthesis and Analysis of Flexible Manufacturing System Cell IEEE Trans On system man and Cybernetics Vol 23 No 2 1993 21 McDermott K J and Wenlong Albert Yao Developing a Hybrid Programmable Logic Controller Platform for a Flexible Manufacturing System 22 McDermott K J and Kamisetty K V Developing an FMS Using IE Tools and Principles Industrial Engineering December 1991 28 23 McDermott K J and Mark I Feldman Intelligent 2D 3D Computer Vision Identification 1995 24 McDermott K J An Industrial Engineering Based Flexible Manufacturing System 25 McDermott K J and William Tereshkovich SARONG Design Interfacing Between CAD Systems and Industrial Robots 26 Michael Sava and Joseph Pusztai Computer Numerical Control Programming Prentice Hall Englewood Cliffs NJ 1990 27 Micheal E Williams Improvement in Machine Vision gives robots affordable Reliable Eyesight Robotics World May 2001 28 Mikell P Groover Automation Production Systems and Computer Integrated Manufacturing Prentice Hall Inc Englewood Cliffs NJ 1987 29 Mik
85. t rung 5 7 Case Study of NJIT FMS Operational Descriptions The working cycle for this FMS proceeds in the following five states State 1 Loading Carts State 1 Initially all four carts on the conveyor system are empty and available for the raw materials to be loaded onto them from the parts presentation station 2 The GE robot P 50 goes to the parts presentation station and loads four parts one by one onto the four carts on the conveyor system The carts move clockwise as they are being loaded 3 Once the four parts are loaded the positions acquired by the four carts are shown in Figure 5 3 X4 AQ X6 X7 cort D 7 TT2 Figure 5 3 Loading state of the conveyor system 72 State 2 Drilling Operation The IBM7535 robot drills four hales on each of the corners of each blank part as the cart stops at the drilling machine State 3 Chamfering Operation 1 The GMF M1 robot moves to position x6 of cart C and picks up the part from the cart and places it into the fixture of the Olivetti machining center 2 Once the part is loaded on the chamfering machine the robot retracts and the chamfering machine chamfers the edges of the upper surface as required 3 After the chamfering machine operation the robot moves to the Olivetti machining center to remove the part that was machined from the holding fixture back to cart C State 4 Milling Operation 1 The GE P 50 robot moves to the conveyor to remove the part from the cart posit
86. t Presentations for the Sequences of LLD esee 120 xi Figure 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 1 10 1 11 1 12 1 13 1 14 1 15 2 l 2 2 2 3 2 4 2 3 2 6 2 7 2 8 2 9 2 10 2 11 LIST OF FIGURES Pata TOW odium Hierarchie structure OF PMS uc uiid tei deca a cnp RUE Functions for hierarchical structure of FMS eeeeee LFMS COmpoTnentsssiio uec E eputvi qam e dM exu uu OetcUUE NASA JIDCNC milling Machine eese ite orta oae ee ree te rotor nno Olivetti Machinitie Center eo i eI Deed Oe eite a iai IBM 7399 RODOLD c ineo oet ar dee tete dedu iiec rM IIRAN vision SVSIeIE oe pute ee oae deae SUR Ad edt doo pu oec bU DREPPI EE D MEUS Us BM MS Ed dore PR General Blectric P 50 TODO ovra rito il E ta tome ee rods GME VEL TODO Cr cate ce Cartrac material handle SV Stein s dedos ee ere che e dedo e tla bue ee tenant Operation of cart on track CODVeyOE iussa peer etn ake aes Control system used in NJIT FMS C H I NJIIT FMS I3yOUL i 5522 iare oos oe pee oo pde petet a ntu ive ocu cate eet desea chee Classification Of CNC machine a imi sd or e ease eather SeFVODHOLOE LG iocus E A onde duae dee epe a Resolver b Synchros c Inductive linear scales d Binary encoders and e Laser inferometer eeseeessss Ballscrew eee EEIE EE AEE AE Mounting Ballnuts and Ballscrews a conventional screw DOBA C
87. tate diagrams 6 4 Modeling Methods The basic relationships between processes in any automated manufacturing line and their representation by PN can be classified as shown in Table 6 2 which shows the modeling method definition of that method Table 6 2 Manufacturing Processes and Their Applications by PN ti t Sequential If two operations are initiated by an Concurrent event Dependency Transition requires two inputs If either of two operations can follow an operation If the sequence of operations follow Cyclic one after another and the completion of the last fires the first Mutually Exclusive If one operation follows the other P2 Conflict Machine can process one part at once resource Sharing Synchronization tigge a One of the major advantages of Petri nets is their ability to analyze a system for properties related to manufacturing control These properties include boundedness or safeness liveness and reversibility Their significance to manufacturing systems is as follows l Boudedness or safeness implies the absence of capacity overflows which assures there is no overflow Safeness is a special case of 1 boundedness 2 Safeness of a resource place indicates the availability of only a single resource 3 Liveness implies the absence of deadlock this property guarantees that a system can successfully produce tokens 81 4 Reversibility implies the cyclic behavior of a system it me
88. tem can utilize the following three control motions e Point to point control e Straight cut control e Contouring control Point to point control PTP The objective of PTP is to move the cutting tool to a predefined location The motion maybe programmed as a sequence of movements along the X and Y axes or direct movement between two points by simultaneously controlling the X and Y axes drives Drilling tapping boring riveting and sheet metal bunching are examples of this kind of control motions 27 See Figure 2 12 26 Y4 Workpart Tool path Tool Starting point oY Figure 2 11 Point to point control system Straight Cut control Straight cut control provides a limited degree of control during the positioning of the tool from one point to another That can be parallel to one of the major axes or it can be performed at 45 Figure 2 13 shows the straight cut operation 27 Workpiece Tool path operations performed during tool motion parallel to x or y axes Starting Cutting tool point Figure 2 12 Straight cut control system Contouring control Contouring control is recognized for its ability to control continuously the cutting tool path in all directions An example for contouring control is shown in Figure 2 14 27 YA Tool profile v Toul path Workpart Tool starting point 4 Figure 2 13 Contou
89. the system is configured for continuous inspection in order to obtain a live video image on a display monitor Lighting and focus adjustments are made until the image is optimized Next using the Itran software a converted digital image of the object is obtained A magnifier tool which enables one to see the values of the pixels within the image can be used to determine if any additional lighting or focusing issues need to be addressed to obtain a clear contrasted image The magnifier also helps determine the threshold settings that need to be used for the inspection 4 3 2 Area Tools The area tool is a daca used to measure certain selected functions within a selected or highlighted area within the field of view The functions include sum edge energy count edge pixels sum gray values and count threshold pixels For this application the count threshold pixels function was used which provides the total number of pixels 58 values above or below a specified threshold value within the area tool The threshold value must also be determined The IVS software provides a histogram of the pixel values within the area tool which is used as a guide in determining the optimum threshold value The count threshold function was set to count the number of pixels that had a value above the threshold value of 9 The area tool was inserted and placed over the image of the largest part in order for it to be large enough for all six different parts After
90. tifiers for the commands is as follows l N Sequence number Is simply the identifying number for the block in ascending numerical order but not necessary in a continuous sequence 2 G Preparatory functions Prepare the MCU for a given operation typically involving a cutter motion 3 X Y Z A or B Dimensional Data Contain the location and axis orientation data for a cutter move 4 F Feed functions Are used to specify the cutter federates to be applied 5 S Speed functions Are used to specify the spindle speed or to setup parameters for constant surface speed operation 6 T Tool functions Are used to specify the cutter to be used where there are multiple choices and also specify the particular cutter offset 36 7 M Miscellaneous functions Are used to designate a particular mode of operation typically to switch a machine function such as coolant supply or spindle on or off 2 6 Case Study for NJIT FMS Chamfering program Chamfering operation takes place by chamfering 7 X 7 Plexiglas block in 45 as shown in Figure 2 22 Olivetti machining center through CNC instructions shown in table 2 2 does chamfering operation Table 2 2 Suggested Program for Olivetti Machining Center Chamfering Operation Sequence Preparatory number functions i d N001 G54 N002 N003 0 000 0 000 Program End Notes Rapid travel to start point Adjust Z height and start cutting Start
91. ts of FMS In this chapter the focus will be on the analysis of an FMS which was designed developed fabricated and programmed at the New Jersey Institute of Technology NJIT The major components included in the FMS are Processing Stations 2 Industrial Robots 3 Material Handling System 4 Control System The components of the NJIT FMS cell are shown in Figure 1 4 Flexible Manufacturing System IBM 7535 Obvitte Mac tuning Center p Tool Grb Robot a Q f PLC Host C omputer SI Cartrac Conveyor System Itran C omputer Vision System Loading amp inspection Station A AutoCAD SmartCAM Figure 1 4 FMS components 1 5 1 Processing Stations e CNC Milling Process Station The NASA II CNC milling machine shown in Figure 1 5 is driven by DC servomotors with a closed loop control system with a 3 axis control motion system It has the capability to travel in the X Y and Z directions with variations of spindle speed Figure 1 5 NASA II CNC milling machine e CNC Chamfering Process Station The Olivetti Machining station which is shown Figure 1 6 is serviced by a GMF MI robot and a carousel of 100 tools Figure 1 6 Olivetti machining center Drilling Process Station The IBM 7535 Robot uses a drilling end effector It is shown in Figure 1 7 Figure 1 7 IBM 7535 robot e Vision System This is a high speed sophisticated unit programmed by using VPL vision planning
92. u OM Honc onsite E inset buen pui oases ees UO CLIE 2 2 CNC Machine Classification cccsccsccscosccsccnccaccscescsceececssceecescscesseuss 22 1 Mechanical SYSTEMS enone Edo toro ndtct Dude ea 2 2 2 COMO SYSTEM oec tede bio tpe cut v etis aito bes ee Visti autas 2 52 29 Coordinate SY SECM cindy noi bet n Selen et oi tutore in suas So ioo cis ales 2 2 5 Moton Control System ouo on paid eoe tuto a dui DR 2 2 3 Number OD AXES sette enuihbpert detelisse toss etaed ea dida to pottea br ead 22 0 Control LOOP SYSE Ius dotate ot uiu mestiere ER D OM RU eee ele 2 3 Numerical Control Computer Numerical Control Direct Numerical Control NC CNC DNC eese 2 5 1 Digital Computer tor NC ten aoi ae E PR Len cide consi E UE 2 3 2 Direct Numerical Control DNC eeeeeeeeeeeeeeeeeeere 2 3 3 Distributed Numerical Control DNC CNC uueussse 245 INC Part PFO PAINS oos oramai eda ONE eu oda iyi dad osuvU U seo inert Desa d eaten 2 5 Manual Data Input MDL eode ERE e a vii Page MA A t A NO m TABLE OF CONTENTS Continued Chapter Page 2 4 2 Manual Part Programming oui eoe esci enel eee RUP elle ieee eases 33 2 4 3 Computer Assisted Part Programming eee 34 2 4 4 NC Part Programming Using CAD CAM cccccececcceeeeeeeeeeeeeeeeeees 34 2 5 Data Preparation for Numerical Control seeeeeeeee
93. y marking in the reachability graph any transition can be enabled by an appropriate firing sequence Thus the sub net is live e Since every node in the reachability graph is a directed circuit containing node m the sub net is reversible with respect to an initial marking 6 6 Petri Nets PNs Vs Programmable Logic Controllers PLCs PNs and PLCs can be compared in terms of design complexity and response time The criteria and the factors needed to make the comparison are shown in Figure 6 8 Comparison of PN and PLC Response Time Minimum time that a control model takes to respond to external event Graphical Adaptability for Scan time PLC Execution time Complexity change in PN Design Complexity Design the control logic for a given specification specification Influenced by physical appearance and method of implementation N Depends on the physical appearance size of the Figure 6 8 Comparison between PN and PLC 6 7 Comparison of Ladder Logic Diagram LLD with PN There are many factors that should be taken into consideration before making a decision between LLD and PN An important factor is the length of the model Shorter models are preferred to use rather then longer models because it s easier to v Understand v Check v Diagnose Y Maintain V Less time to enter to the controller Y Less memory used V Faster in response 92 Y Low cost Y Less design complexity Y Adaptabilit
94. y to change in specifications Table 6 11 makes a comparison between PN with LLD on the basis of some key factors PN presentation for sequences of LLD is shown in appendix H Table 6 11 Comparison of PN and LLD l Easiness of readability e The same node may appear i REPET i No repetition for any node understandability and reliability multiple times 2 Improvement in modifiability e Need more basic elements to No modeling for timers and and maintianbility model timers and counters counters e Lack of ability to know the properties of the system before implementation Difficult because a node appears more than one time in the diagram so the tracking of control becomes difficult 5 Software availability e Excellent standard industry ractice Poor no commercial software J e Excellent 1 Methodology in place to handle timeout errors 2 Can include unexpected event error 3 Minimum programming for diagnostics Ability to analyze and check the properties for the system 3 Easiness of modeling and simulation Easy it helps to track the 4 Debugging of the control logic system dynamically Poor 1 Error handling is additional 2 Has no methodology 6 Error handling and diagnostics CHAPTER 7 CONCLUSIONS This research accomplished the following e Utilized and implemented industrial engineering principles that are used in Flexible

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