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Contents
1. 4 5 6 7 8 SECONDARY BOUNDARY IN FEET U S Patent May 27 1980 Sheet 7 of 12 4 205 308 MEMORY ADDRESS FUNCTION 1920 SYSTEM CONSTANTS 1720 DIAGNOSTICS 1320 AUTOMATIC SHUTDOWN SEQUENCE 1020 POSITION MONITORING ALARMING AND INITIATION OF AUTOMATIC SHUTDOWN 270 INTERRUPT SERVICE ROUTINE 120 SCHEDULER 50 INITIALIZATION PROM MEMORY MAP U S Patent 27 1980 Sheet 8 of 12 4 205 308 PWRON INITIALIZE SYSTEM READ DEBOUNCE AND UPDATE EVENT PANEL SWITCHES SET SYSTEM TO NO ALARM MODE RESET ALARM MODE SHUTDOWN ARTINE NO ALARM YES CLEAR ALARM LIGHT AND ALARM HORN 1 SEC SINCE LAST ANGLE UPDATE NO YES U S Patent 27 1980 Sheet9 of 12 4 205 308 Sein 8 SHUTDOWN IN PROGRESS 4 SEC SINCE LAST SHUTDOWN oe UPDATE SHUT DOWN OPERATION 01 SEC SINCE LAST SWITCH UPDATE U S Patent 27 1980 Sheet 10 of 12 4 205 308 FIG 1 READ ANGLE SENSOR SUPPLY VOLTAGE WITHIN ADJUSTMENT LIMITS NO YES TURN OFF OUT OF TURN ON OUT OF J ADJUSTMENT LED ADJUSTMENT LED READ ANGLE SENSOR APPLY SUPPLY VOLTAGE CORRECTION AND COMPUTE ANGLE NO ANOTHER SENSOR CALCULATE ARM POSITION ARM WITHIN SPECIFIED VOLUME NO U S Patent May 27 1980 Sheet 11 of 12 4 205 308 E 1 4 w ES S AL2. When an installation of this type is being designed minimum requirements are set for the reach of the arm These requirements are expressed in terms of the maxi mum horizontal displacement of the tanker parallel to and away from the jetty relative to a datum position the maximum displacement away from the jetty due to variations in the distance between the tanker manifold and the tanker rail and the maximum vertical displace ment due to variations in the water level and the height of the tanker manifold relative to the water level These displacements define a three dimensional space that is rectangular in section when viewed in plan or in eleva tion either parallel to or perpendicular to the jetty and this space is known as the arm s operating envelope The arm must be able to accommodate all of these dis placements so that a safe and secure connection to the tanker s manifold can be established and maintained within the limits of this envelope Most articulated arms are counterbalanced so that when empty they are substantially self supporting However the weight of the oil or other fluid in the arm during use is not counterbalanced and thus must be supported in part by the tanker manifold to which the arm is connected Clearly the stress on the manifold increases with the extension of the arm In addition the manifold always faces towards the tanker rail and the stress to which the manifold can be subjected in a direc ti
3. as defined in claim 1 wherein said means for sensing an angle representative of the vertical orientation of either of said limbs in cludes a pendulum potentiometer coupled to said limb 5 Apparatus for sensing position as defined in claim 1 wherein said calculator means includes means for re trieving the values of said boundaries from said storage means and means for comparing the actual spatial posi tion of said end of said arm with the values of each said boundaries 6 Apparatus for sensing position as defined in claim 1 wherein said calculator means includes a digital proces sor 7 Apparatus for sensing position as defined in claim 6 including means for converting the values of said first second and third angles into digital values for use by said digital processor 8 Apparatus for sensing position as defined in claim 6 wherein said storage means includes means for storing a computer program for use by said processor said pro cessor having means for using said program to direct the checking of values of said first second and third angles and for using said angle values to calculate the spatial position of the end of said arm 9 Apparatus for sensing position as defined in claim 1 including means for providing a disable signal when said end of said arm moves a predetermined distance outside said working area 10 Apparatus for sensing position as defined in claim 9 wherein said predetermined distance is determined by the sp
4. by the processor 41 insures that correct sensor angles are calculated in spite of power supply voltage variations After the correct values of the sensor angles are ob tained the processor 41 retrieves the values of the limb lengths from the PROM 37 retrieves correct angle position data from the data memory 42 and proceeds to calculate the X Y and Z positions of each of the loading arms The end position of each of the loading arms is compared one at a time with the safe boundaries for the corresponding arm When any arm is outside any of the corresponding safe boundaries an alarm signal is provided to the expander 46 FIG 6B causing the horn H and an appropriate alarm light to be energized When the loading arm extends outside the safe boundaries the processor takes an additional reading from each of the sensors calculates a new arm position and uses the new arm position and the previous arm position to calculate the distance the arm has moved Since readings are taken at one second intervals the distance moved between readings is also the speed of the arm in the distance moved per second The proces sor then compares the arm speed with a data table in the PROM 37 to determine how far outside the safe bound ary the arm can extend before initiating a shutdown A portion of the data table from the PROM is reproduced in graph form in FIG 8 For example when the speed of the end of the arm is 8 inches per second the arm may extend
5. the out board end of the arm and for sounding an alarm when ever the end of the arm extends outside the specified envelope SUMMARY OF THE INVENTION The present invention comprises a system for sensing the position in space of the end of an articulated fluid loading arm the arm comprising a plurality of pivotally connected booms or limbs one of which is pivotally mounted on a vertical riser or other fixed support The system includes means for sensing a first angle represen tative of the vertical orientation of one limb of the arm means for sensing a second angle representative of the horizontal slew of the arm means for sensing a third angle representative of the vertical orientation of the other limb or limbs and means for deriving from the sensed angles an indication of the spatial position of the end of the arm The system further includes means for storing the spatial boundaries of a safe working area for the end of the loading arm means for comparing the actual posi tion in space of the arm with the safe boundaries and means for generating an alarm signal when the end of the arm reaches beyond any of the safe boundaries When the arm continues to move beyond this first set of safe boundaries to a second set of boundaries the sys tem generates a shut down signal which disables the loading arm BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is schematic side elevation of an articulated fluid loading arm mounted on a jetty o
6. 6 feet outside the boundary before the arm is shut down As long as the arm extends outside the safe boundary the alarm H continues to sound and the corre sponding warning light AI AN remains energized The various steps of reading the sensors calculating the positions of the loading arm limbs and sounding the alarm can be seen in the flow chart of FIGS 10 12 As stated hereinbefore the shut down procedure can be varied to satisfy the wishes of a customer For exam ple one such procedure may be as follows 1 Provide a control closure signal to the customer to instruct him to turn off the fuel pumps by providing a closure signal to the shut down circuit D1 of FIG 6B 15 20 30 35 40 45 55 60 65 12 2 The customer closes switch S7 to signal the turn off of the fuel pumps 3 The closed switch S7 causes the microcomputer to turn on power to the hydraulic system so that the load ing arms may be operated 4 The microcomputer provides a control signal which closes the ball valves at the outboard end of each loading arm to prevent oil spills 5 The closing of the ball valve also closes switch S8 to signal the microcomputer that the ball valve is closed 6 microcomputer provides control signal which opens the couplers on all of the loading arms 7 The operator moves all of the loading arms away from the tanker and into the stored position adjacent the risers It is also possible to program th
7. ARM Y MODE OUND ALARM HORN UPDATE ARM COORDINATES AND CALCULATE VEL NO SHUTDOWN YES MODE SHUTDOWN IN PROGRESS GET VELOCITY DEPENDENT SHUTDOWN LIMITS NO lt a gt YES SET SYSTEM TO SHUTDOWN STATE YES XY 4 205 308 Sheet 12 of 12 U S Patent 27 1980 4 205 308 i PROGRAMMABLE ALARM SYSTEM FOR MARINE LOADING ARMS BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to articulated fluid transferring apparatus and more particularly to marine loading arms and alarm systems for determining the spatial position of the outer end of such arms with respect to the arm booms or limbs 2 Description of the Prior Art Fluid loading arms constructed of articulated pipe are extensively used in the petroleum industry for transfer ring oil or other fluids between a jetty wharf or other loading station and a marine tanker moored alongside Such an arm generally comprises an inboard boom or limb supported on a vertical riser pipe by pipe swivel joints to facilitate pivotal movement about horizontal and vertical axes and an outboard boom or limb con nected by a pipe swivel joint to the inboard limb so as to be pivotal relative thereto about a horizontal axis The outer end of the outboard limb is adapted to be con nected to a pipe manifold on a tanker located within the reach of the arm such as by a remotely controllable coupler device
8. M 37 FIG 6A provides test signals to the alarm lights AI AN FIG 6B These test signals can be applied one at a time to the alarm lights followed by other desired combinations of test signals to various alarm lights The PROM 37 can be programmed to provide any combination of tests desired by the opera tor of the alarm system When the test switch S3 is closed a test program from the PROM 37 causes the expander 46 FIGS 5 6B to supply test signals to the shut down circuits DI DN with the desired combination of test signals being written into the test program When the test switch S4 is closed the processor 41 checks the posi tions of the event switches S7 S14 FIG 6B and dis plays the open or closed status of each of these switches on the alarm lights AI AN The operation of the microprocessor circuit will now be described in connection with the circuit of FIGS 6A 6B the PROM memory map of FIG 9 and the flow charts of FIGS 10 13 When power is initially applied to the microcomputer circuit of FIGS 6A 6B or when a reset push button switch R FIG 6A is closed the low value of voltage from the processor 41 or from the switch R applied to the RESET leads of the processor 41 and memory 42 clears all data from the data memory 42 and from the scratch pad memory of the processor 41 sets the program counter of the pro cessor to zero and clears the program counter stack An alarm on switch 55 is then closed to turn on
9. United States Patent Haley et al EET en ee 54 PROGRAMMABLE ALARM SYSTEM FOR MARINE LOADING ARMS 75 Inventors Frank Haley Upland Louis S McTamaney San Jose both of Calif 73 Assignee FMC Corporation San Jose Calif 21 Appl 853 800 22 Filed Nov 21 1977 51 Int CI2 08 21 00 65 1 04 GOIC 1 00 GO1B 3 56 52 US CL 340 686 33 1 M 137 556 141 387 364 559 58 Field of Search 340 679 685 686 689 364 110 559 137 554 556 615 212 39 A 39 MS 222 41 42 141 94 387 285 93 33 1M 56 References Cited U S PATENT DOCUMENTS 1 931 107 10 1933 Dowell et al 114 230 2 588 842 3 1952 Hutt 248 82 2 855 886 10 1958 Svoboda 116 124 2 898 954 8 1959 Freeman 141 86 2 927 607 3 1960 Bily 137 615 3 050 092 8 1962 et al 141 387 3 073 280 1 1963 Thiel 116 124 3 566 386 2 1971 Hamilton 340 267 3 638 211 1 1972 Sanchez 340 685 3 819 922 6 1974 Horn et al 235 193 3 833 130 9 1974 Gerdes et al 212 39 3 833 932 9 1974 Hamilton 340 267 C 3 854 128 12 1974 Yamagishi 340 267 C 3 922 789 12 1975 Sarrell 33 125 R TIMER es PROCESSOR MULTIPLEX SWITCH CLOCK GEN 4 42 PI gt Op
10. cting of the arm A relatively small diagnostic program and system con stants such as lengths of the arm limbs are also stored in the PROM The details of the use of the contents of the PROM will be discussed hereinafter Information which is stored in the PROM 37 is re trieved by providing memory address signals on the address inputs A0 A10 The lower 8 bits of the address are latched in an 8 bit latch 43 and coupled to the inputs A0 A7 of the PROM while the remaining bits of the address are continuously supplied by the microproces sor and do not need to be latched The lower 8 bits on the inputs 11 18 are stored in the latch 43 when a strobe pulse is provided by the ALE lead of the processor 41 to the DS2 input of the latch 43 These signals are re tained in the latch 43 and are continuously available on the output leads 01 08 of the latch One such latch which can be used in the present invention is the 8212 made by the aforementioned Intel Corporation Details of this latch may be found in the aforementioned MCS 48 Microcomputer User s Manual 1976 by Intel Cor poration The data memory chip 42 may include a random access memory or RAM having discreet addressable locations each of which provides storage for a word The word may be for data and may contain specific fields useful in a variety of operations Normally when the processor is in need of data or instructions it will generate a memory cycle and provide an address to the p
11. ds and the system is shut down if the arm moves a predetermined distance farther into the unsafe area 19 Claims 16 Drawing Figures ALARM 1 LIGHTS i SHUT 1 0 4 DOWN EXPANDER 46 Alp CONVERTER U S Patent May 27 1980 Sheet 1 of 12 4 205 308 U S Patent 27 1980 Sheet 2 of 12 4 205 308 Iib _ 4 205 308 Sheet 3 of 12 1980 U S Patent May 27 SBHOLIMS nivis S9VINOA Xlddns os Y3LYSANO9 HOLIMS ov NAOQ NMOd 1 AuOW3W SELE e v uossaooud U S Patent 27 1980 Sheet 4 of 12 4 205 308 atv fl m Er 1 6 ci ME 64 55 65 E Qi 41 a 9 12 PROCESSOR 13 18 8 gt DATA MEMORY RAM 79 2 p o U S Patent May 27 1980 Sheet 5 of 12 4 205 308 wo W21 wio WZ6 WI3 WI8 ALARM PI m SHUT gt DOWN 1 g e on gt 45 5 3 VOLTAGE Pg ae VOLTAGE o o V 53 pENSORT 9 49 lt 8 P2 2 4 z __ ANGLE si SENSOR 2 i ANGLE o iC SENSOR 3 1 ANGLE U S Patent 27 1980 Sheet 6 of 12 4 205 308 Ed SPEED INCHES PER SECOND g
12. dure is initiated is determined by the velocity of the connecting device If desired the location of the safe boundaries may also be made to depend upon the velocity of the end of the loading arm An inner boundary may be defined and stored in the microcomputer memory and a warning sounded when an arm moving at a maximum velocity reaches the inner boundary When the arm is moving at a speed less than the maximum a look up table stored in memory provides an extension value to be added to the inner boundary This look up table is similar to the graph of FIG 8 and is used in the manner discussed above in connection with the shut down boundaries The number of steps in the shut down procedure and the action to be taken in each of these steps may vary due to the wishes and requirements of the customers who using the marine loading arm In some cases the shut down procedure which is provided by the present invention may consist only of providing a shut down signal to the customer while in other cases a more elaborate procedure is required In any case the mi crocomputer can be programmed to provide a desired signal or sequence of signals to the customer Details of the microcomputer circuits which perform these opera tions are described in detail below FIG 5 is a block diagram representation of the basic circuitry of the programmable marine loading arm alarm system of the present invention Details of the circuit can be seen b
13. e microcomputer so that the loading arms are moved into the stored posi tion by control signals from the microcomputer so that operator control is not required Several of these steps may be monitored by closing other of the switches S9 S14 if desired If more status input switches are needed they can be added to the switch 38 and additional I O expanders 46 can be con nected to the processor to control additional shut down circuits if such circuits are needed Another embodiment of the present invention is dis closed in FIG 14 wherein all of the angle sensors are mounted on the riser 14 and wherein only the upper portion of the riser and the inner end of the loading arm s inboard limb 10 are shown All of the remaining portions of this embodiment of the invention are identi cal to the embodiment shown in FIGS 1 13 The basic details of the means of mounting the loading arm on the riser are shown in FIG 14 In the embodiment of FIG 14 the inboard end of the limb 10 includes an elbow 10a which is welded or other wise connected to a swivel joint 75 A flange 75a of the joint 75 is fixed to the elbow 10a with the flange 75a free to rotate about the outer end of an elbow 14a The lower end of the elbow 14a is pivotally connected to the upper end of the riser 14 by another swivel joint 76 Thus the flange 75a rotates about the horizontal axis 12 when the outer end of the limb 10 is raised or lowered The swivel joint 76 is mounted wi
14. e zero or ground reference value of voltage at an input of the analog switch 495 is coupled to the input to the A D converter 50 and converted to a digital signal which should be all binary O s or at least a low value If the signal from the converter 50 is greater than the zero value by a predetermined amount the proces sor 41 causes the data memory to provide a warning signal to energize another LED 60 The signal level control 58 can be adjusted until both LED 59 and LED 60 are deenergized to compensate for any change in operation of the circuitry of FIGS 6A 6B The microcomputer circuitry includes a crystal 64 FIG 6A which is used to develop the clock and other timing signals These timing signals are continuously monitored by a watchdog timer 65 which provides a warning signal on the output lead 3 when timing sig nals are not received at the normal rate In the present invention the crystal 64 and processor 41 develop tim ing pulses at a rate of one per second and scan each of the sensors to obtain angle readings once per second The timing pulses are coupled to the timer 65 and the transistor Qi with the time between pulses being ap proximately 1 second During the time between pulses current flows from a source of potential V through a resistor R1 to charge a capacitor C1 with the polarity shown in FIG 6A The value of the voltage on the capacitor C1 is determined by the time the capacitor charges which is the time betwe
15. ed in claim 15 including means for sensing the value of said supply voltage and means for generating a corrective angle signal whenever said supply voltage varies from a stan dard value 17 A programmable marine loading arm alarm sys tem for monitoring the position in space of the end of an articulated arm having an inboard limb pivotally con nected between an outboard limb and a riser said alarm system comprising an inboard elevation sensor for developing first signal representative of the angle of said inboard limb relative to a vertical plane an inboard direction sensor for developing a second signal representative of the angle of said inboard limb relative to a predetermined horizontal direc tion an outboard elevation sensor for developing a third signal representative of the angle of said outboard limb relative to a vertical plane means for converting said first second and third sig nals into digital form digital calculator means for using the digital values of said first second and third angles to calculate the spatial position of the outboard end of said loading arm digital memory means for storing the spatial bound aries of a working area for said end of said arm calculator means for comparing the actual spatial position of the end of said arm with said boundaries from said digital memory and means for generating an alarm signal when the spatial position of said end of said arm extends outside the w
16. eed of movement of said end of said arm and wherein said speed of movement is determined by said means for calculating said velocity 11 Apparatus for sensing position as defined in claim 9 wherein said predetermined distance is inversely pro portional to the velocity of said end of said arm and wherein said velocity of said end is determined by said means for calculating said velocity 12 A programmable marine loading arm alarm sys tem for monitoring the position of each of a plurality of marine loading arms and for providing an alarm when the outboard end of any of said loading arms extends outside the boundaries of a three dimensional working area each of said arms including an inboard limb pivot 4 205 308 15 ally connected between an outboard limb and a riser said alarm system comprising a plurality of inboard elevation sensors for sensing a first angle representative of each of the inboard limbs relative to a vertical plane 5 a plurality of inboard direction sensors for sensing a second angle representative of each of the inboard limbs relative to a predetermined horizontal direc tion a plurality of outboard elevation sensors for sensing third angle representative of each of the outboard limbs relative to a vertical plane calculator means for using the values of said first second and third angles to calculate the spatial position of the outboard end of each of said loading arms memory means for stor
17. en pulses Each time a positive timing pulse is applied to the base of the transis tor Q1 the capacitor C1 discharges through the transis tor However if capacitor charges for more than 1 second the voltage on the capacitor C1 increases to a high value causing the timer 65 to provide a low value of voltage at the output lead 3 The low value of output voltage at the cathode of an LED 61 and the positive voltage at a terminal 68 cause the LED 61 to be ener gized and to warn the operator that the processor is not providing the proper timing pulses One timer which can be used in the present invention is the NE555 which is available from several manufacturers A plurality of switches 81 54 FIG 6A provide test signals for performing diagnostic checks on various portions of the microcomputer system and on the sens 20 25 30 35 40 45 50 55 60 65 10 ing devices These switches are used in conjunction with a diagnostic program which is stored in the PROM 37 The test switch S1 is used in checking the value of the supply voltage for the system and in adjusting the signal output level of the A D converter 50 FIG 6B When the test switch S1 is closed the voltage from the supply voltage 45 is coupled to the processor and the signal level control 58 adjusted as described hereinbe fore to obtain a standard signal from the output of the A D converter 50 When the test switch S2 is closed a test program from the PRO
18. h of the safe boundaries of three dimen sional space and provides a warning signal when any arm extends outside any of the safe boundaries When the arm continues to move away from the safe area the apparatus checks the velocity of the out of bounds arm and determines when the arm must be disabled and or disconnected to prevent damage If desired the present invention can be used to con trol a plurality of marine loading arms each having a different length and each having a different volume of operating envelope The lengths of these individual arms and the boundaries of each of the envelopes can be stored in the PROM 37 and the actual position of each arm compared with the corresponding safe boundaries for that particular arm and an alarm signal can be pro vided when any of the arms move outside any of the safe boundaries for that arm Although the best mode contemplated for carrying out the present invention has been herein shown and described it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention What is claimed is 1 An apparatus for sensing the position in space on the end of an articulated arm having a plurality of pivot ally interconnected limbs a first one of which is pivot ally mounted on a fixed support the apparatus compris ing means for sensing a first angle representative of the vertical orientation of said first limb mea
19. haft encoders or other known devices to provide analog outputs may be used to sense the angles d g and f The angles d and g may also be obtained by pendulum potentiometers P1 and P2 which are mounted on the respective limbs 10 and 15 FIG 3 One such pendulum potentiometer which may be used is the Model CP17 0601 1 manufactured by Humphrey Inc San Diego Calif s Since the sheaves 19a and 19b are positioned in a fixed relation to the attitude of the outboard limb 15 the outboard potentiometer P2 may be mounted on the sheave 195 at the position P2 FIG 3 where it will provide elevation angle readings identical to the read ings obtained from a potentiometer mounted on the outboard limb The electrical wiring may be simplified when the potentiometer is mounted on the sheave 190 The potentiometer P1 can be mounted on the counter weight 22 if desired to obtain the elevation angle of the 4 205 308 5 counterweight and of the inboard limb 10 The slew angle f is obtained by a direction potentiometer or angle encoder which is connected between the riser 14 and the inboard limb 10 One such encoder which may be used is the Model CP17 0646 1 manufactured by Hum phrey Inc The analog signals which are obtained from the vari ous potentiometers can be converted to digital signals which are used by a microcomputer to compute the exact spatial position of the connecting device 18 The safe boundaries defined by t
20. he planes 27 28 29 30 33 and 34 are stored in the microcomputer memory and these boundaries are continually compared with the actual position of the connecting device When the actual position of the connecting device 18 reaches any of the boundaries of the safe area the microcomputer provides a warning signal to an alarm device If the connecting device 18 continues to move away from the safe area the microcomputer provides a shut down sig nal which provides a warning signal to both the cus tomer on the tanker and to the operator of the marine loading arm so that the fuel pumps can be turned off the proper valves can be closed and the connecting device 18 can be disconnected from the tanker mani fold If desired the shut down signal can be used to turn off the pumps and disable the arm The distance which the connecting device moves outside the safe area be fore the warning signal is produced and the arm is dis abled is determined by the velocity at which the con necting device changes location In addition to the values of the angles which must be measured the lengths of the arm s inboard and outboard limbs 10 15 must be used to calculate the spatial posi tion of the outer end of the arm These lengths having a value of A and B respectively are stored in the mem ory portion of the microcomputer which performs the calculations The various angles and lengths used are shown in FIGS 3 and 7 with FIG 7 being a diagram matic
21. ing the working boundaries of the outboard end of each of said arms means for comparing the actual spatial position of 20 each of said arms with the corresponding working boundaries for that arm means for calculating the velocity of any loading arm which extends outside said working boundaries and for using the calculated velocity to determine the position of a second boundary at which said system generates a disable signal and alarm means connected to said comparison means for providizg an alarm signal whenever the outboard end of any of said loading arms extends outside said working boundaries of said arm 13 A programmable alarm system as defined in claim 12 including means for providing shut down signals when the outboard end of any of said loading arms extends a predetermined distance outside any of said working boundaries 14 A programmable alarm system as defined in claim 13 wherein said predetermined distance is determined by the velocity of said outboard end of said loading arm and wherein said velocity of said outboard end is deter mined by said means for calculating said velocity 15 A programmable alarm system as defined in claim 25 35 12 wherein each of said elevation sensors includes a potentiometer means for coupling said potentiometer 45 to a corresponding one of said limbs and a supply volt age coupled to said potentiometer 50 55 60 65 16 16 A programmable alarm system as defin
22. m A SENSOR nh SUPPLY VOLTAGE 38 STATUS SWITCHES 50 11 4 205 308 45 May 27 1980 3 932 855 1 1976 Hamilton 340 685 3 944 798 3 1976 Eaton 364 559 4 084 247 4 1978 Ball 364 559 Primary Examiner John W Caldwell Sr Assistant Examiner Joseph E Nowicki Attorney Agent Firm Lloyd B Guernsey W William Ritt Jr John F Verhoeven 57 ABSTRACT A system for sensing the positon in space of the outer end of an articulated fluid loading arm while it is con nected to a marine tanker or other transport vessel and for sounding an alarm if the arm s operating envelope is exceeded The sensing system includes means for deter mining various angles representative of the orientation of the booms or limbs of the arm and a microprocessor for using these angles to compute the spatial position of the arm s outboard end The boundaries between the safe and unsafe areas of operation of the arm are stored in a digital memory and compared with the actual posi tion of the arm The boundaries which define the safe areas can be any desired shape and the shape can be readily changed by storing a new set of boundary values in the digital memory If desired the location of the boundaries can be made to depend upon the velocity of the arm as it is being maneuvered When the outboard end of the arm moves into an unsafe area an alarm soun
23. mount of rotation from a fixed position For example when the arm s inboard limb 10 FIG 14 is oriented horizontally the inner portion of the encoder Pia is in a zero position and provides a signal repre senting this position As the outer end of the limb 10 is raised the elbow 10a the flange 75 and the encoder Pla rotate clockwise as viewed from the left of FIG 14 causing the encoder to provide a signal which continu ously provides the attitude of the limb 10 Such encod ers are available from several manufacturers and one encoder which can be used in the present invention is the Model GCC 43 13H30 made by Litton Industries Chatsworth Cal When the inboard sheave 195 FIGS 3 14 is rotated by means not shown to raise or lower the outer end of the limb 15 FIG 3 the bracket 79 and thus the en coder P2a rotate about the horizontal axis 12 thereby providing an output signal which represents the attitude of the outboard limb 15 When the marine loading arm is rotated slewed in a horizontal direction about the vertical axis 13 FIGS 4 14 the magnet 85c rotates relative to the slew encoder P3a causing the encoder P3a to provide a signal which represents the horizontal orientation of the inboard limb 10 and thus of the entire marine loading arm The apparatus of the present invention checks the angular position of each loading arm once every sec ond compares the position of the outboard end of each arm against eac
24. ns for sensing a second angle representative of the horizontal orientation of said arm means for sensing a third angle representative of the vertical orientation of a second limb calculator means for using the values of said first second and third angles to calculate the spatial position of the end of said articulated arm 10 20 25 35 40 45 50 55 65 14 means for storing the spatial boundaries of a working area for said end of said arm means for comparing the actual spatial position of the end of said arm with said boundaries means for calculating the velocity of the end of said arm and for extending the boundaries of said work ing area by an amount which is dependent upon the arm velocity and means for generating an alarm signal when the spatial position of said end of said arm equals any of said boundaries 2 Apparatus for sensing position as defined in claim 1 wherein each of said means for sensing an angle in cludes an absolute angle shaft encoder and means for connecting said encoder between said arm and said fixed support 3 Apparatus for sensing position as defined in claim 1 wherein each of said means for sensing an angle in cludes an absolute angle encoder and a magnet means for mounting said encoder on either said arm of said fixed support and means for mounting said magnet adjacent said encoder on the other of said fixed support or said arm 4 Apparatus for sensing position
25. on a jetty 23 provided with a flexible fender 24 The mean sea level is represented in FIG 1 by the horizontal solid line 26 and the high and low water lines are represented by dash dot lines 26a 26b respec tively above and below the line 26 The installation is designed to accommodate a variety of tankers and tanker movements during a loading operation The arm s operating envelope is defined as being limited by the vertical planes 27 28 29 and 30 and horizontal planes 33 34 as illustrated in FIGS 1 and 2 However it should be understood that the microcomputer can be used to define an operating envelope having any desired shape and the actual arm position can be compared with such an operating envelope All that is required is that the coordinates of the boundaries of such an operat ing envelope be stored in the memory of the microcom puter and the actual arm position compared therewith Curved envelopes can be closely approximated by a series of short straight lines As indicated in FIGS 1 and 2 the freedom of move ment between the planes 27 and 28 in the horizontal direction away from the jetty 23 is accounted for by the portion L1 which represents the variation in distance between the manifold and rail of various tankers and a portion L2 which represents the allowable movement of a tanker towards or away from the jetty The freedom of movement between planes 33 and 34 in the vertical direction FIG 1 is accounted for b
26. on perpendicular to the rail and hence to the jetty is greater than the stress to which it can be subjected parallel to the rail The stress parallel to the rail in creases with an increase in the slew angle that is the angle between the vertical plane in which the arm re sides and the vertical plane through the riser and normal to the edge of the jetty Thus to prevent the stresses on the manifold from exceeding safe limits the extension of the arm and the slew angle must be limited To achieve this limitation alarm systems have been provided for actuation in the event of the angle between the inboard and outboard limbs exceeding a predeter mined limit or in the event of the slew angle exceeding a predetermined limit These independent limits result in operating characteristics which are not entirely satis 5 45 50 55 60 65 2 factory for they in effect define a space within which the arm can operate that is bounded either by arcuate surfaces or by planes passing through the vertical pivot axis of the arm on the riser Thus if a specified rectan gular operating envelope is to be accommodated fairly extensive areas outside this envelope will also be within the operating range of the arm and the stresses which occur when the end of the arm is in these outside areas can substantially exceed those occurring within the envelope It is therefore important that a system be provided for monitoring the actual position of
27. ops a busy signal which is coupled to the processor 41 When the busy signal dis appears the processor 41 provides a fetch signal to one input of an AND gate 71 FIG 6A and provides an RD output strobe signal through an inverter 72 to the other input of the gate 71 These signals combine to provide an OE output enable signal which transfers binary data signals to the outputs B0 B7 of the con verter 50 One such A D converter which can be used in the present invention is the 8703 made by the Tele dyne Semiconductor Company Mountain View Calif and details of this converter can be found in the specifi cation sheets on it that are available from this company The details of the angle sensors for example the sensor P1 may be seen in FIG 6C The sensor com prises a potentiometer having one end 54 connected to a source of positive voltage such as a 12 volts and the other end thereof connected to a ground reference An arm 55 is slidably positioned along the potentiome ter with the position of the arm being determined by the attitude of the limb of the marine loading arm to which the potentiometer is attached The voltage at an output terminal 53 is determined by the position of the arm 55 This voltage is coupled to the microprocessor 41 which uses the value of the voltage to calculate the position of the loading arm limb on which the potentiometer is mounted It can be seen that if the voltage at the termi nal 54 of the po
28. orking boundaries of said arm 18 A programmable alarm system as defined in claim 17 including means for using successive spatial positions of the end of said arm to determine the velocity of the end of said arm and for using the calculated velocity to determine the position of a second boundary at which said system generates a disable signal 19 A programmable alarm system as defined in claim 17 wherein said digital memory includes means for storing the boundaries of an operating enevelope having any desired shape and wherein said calculator includes means for comparing the actual arm position with the boundaries of said operating envelope
29. r wharf accord ing to the present invention illustrating in phantom the arm in several operating positions and also showing the arm s operating envelope as viewed from the side FIG 2 is a schematic plan view of the arm and oper ating envelope of FIG 1 FIG 3 is a schematic side elevation of the arm of FIGS 1 and 2 illustrating the arm s geometry from which the location of the arm s outer end can be de rived FIG 4 is a schematic plan view of the arm of FIG 1 illustrating the arm s geometry in a horizontal plane FIG 5 is a basic block diagram representation of the marine loading arm alarm circuitry FIGS 6A and 6B comprise a schematic diagram of a microcomputer circuit which can be used to calculate the various positions of the end of the loading arm and compare these positions with the safe boundaries which are stored in the microcomputer memory FIG 6C is a schematic diagram of an electronic de vice for sensing the attitude of the inboard and outboard limbs FIG 7 is a diagrammatic representation of the arm of FIGS 1 and 2 illustrating in three dimensional geome 3 try the location of the arm s outer end in relation to the various angles which can be sensed FIG 8 is a graph illustrating the relationship between loading arm velocity and the position of the shut down boundaries FIG 9 13 illustrate flow charts which can be used in understanding the operation of the microcomputer FIG 14 is a pe
30. representation of one of the marine loading arms and illustrating in three dimensional geometry the loca tion of the inboard and outboard limbs in relation to the various angles which can be measured by the sensors FIG 7 also shows the position of these angles and the lengths of the limbs in relation to the X Y and Z loca tions in space which can be calculated from the readings of the sensors The position of the outboard end of the arm is calcu lated in two steps First the position of the connector flange in the plane of the arm is calculated using the origin O of the coordinates at the top of the riser and obtaining a point having the polar coordinate values of Vn Zn as the location of the connector flange The flange position is computed using the following rela tionships yn A sin 4 sing Zn A cos d B cos g Then projecting the flange position onto the X Z axis the rectangular coordinates of the flange position can be calculated using the following relationships X Vn sin f Y Vn cos f Z Zn 25 30 40 45 55 65 6 lt Each of the quantities X Y and Z is computed and compared with the boundary values and an alarm is sounded if any limit is exceeded When the connecting device moves outside the safe boundaries by a predetermined distance a shut down procedure is initiated to prevent damage to the arm and or tanker manifold The distance from the safe boundary at which the shut down proce
31. rogram memory or to the data memory The data or word stored at the addressed location will subsequently be retrieved and provided to the processor 41 The data memory chip 42 also includes an I O expander input output expander section which increases the nuniber of input output ports which are available for use by the processor 41 The I O portion of the chip 42 provides control signals for other portions of the computer cir cuitry One such data memory and I O expander which can be used with the present invention is the 8156 made by the aforementioned Intel Corporation In order to increase the number of output devices such as alarm lights and shut down devices which may be individually controlled by the microprocessor 41 an I O expander 46 is connected to the processor 41 The 10 15 20 25 30 35 40 45 50 55 60 65 8 expander includes one 4 bit input port P20 P23 which is connected to the corresponding leads 20 23 in the processor The expander 46 includes a total of 16 input output leads which can be used to provide individual signals to or from a total of 16 input output devices The expander is capable of providing relatively large values of output current to these output devices There fore in addition to increasing the number of output devices which can be controlled by the microprocessor 41 the I O expander can operate devices requiring signal currents which are larger than the curren
32. rspective of a portion of a loading arm equipped with another embodiment of the present in vention for sensing the attitude of the inboard and outboard limbs of the arm DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS 1 4 of the drawings an articu lated arm according to the present invention is shown comprising an inboard limb 10 pivotally connected about a horizontal axis at 12 to a riser or other fixed conduit 14 The articulated arm also comprises an out board limb 15 pivotally connected about another hori zontal axis 17 to the inboard limb and a connecting device 18 such as a pipe flange or coupler at the outer end of the limb 15 arranged for connecting the arm to a tanker manifold A sheave 19 is fixed to the inboard end of the limb 15 and is mounted for pivotal movement about the horizontal axis 17 at the outboard end of the limb 10 The sheave 19a is coupled by a pair of cables 20a 206 to another sheave 19b which is mounted for pivotal movement about the horizontal axis 12 at the upper end of the riser 14 The inboard sheave 195 can be rotated about the horizontal axis 12 by any of the means not shown commonly used for raising and lowering the outer end of the outboard limb 15 A counterweight 22 connected to the inboard limb 10 neutralizes or greatly reduces the tendency of the loading arm to turn about the horizontal axis 12 regardless of the position of the arm The entire articulated arm assembly is mounted
33. ser s Manual 1976 by Intel Corporation The program memory 37 may be a programmable read only memory or PROM which is available from several manufacturers A series of instructions compris 4 205 308 7 ing the program and the lengths of the limbs may be loaded into the program memory 37 by the manufac turer of the PROM or the PROM may be loaded by a PROM programmer which is available from several manufacturers The contents of the program memory 37 cannot be changed by the microprocessor 41 The mem ory contents can only be changed by removing the PROM from the circuitry of FIG 6A and inserting it into the PROM programmer where the data may be removed from the memory and new data stored in the memory One PROM which may be used in the present invention is the 2708 made by the Intel Corporation and such PROM is described in the Intel 1976 Data Catalog The general storage areas of the PROM 37 as used in the present invention may be seen in FIG 9 Relatively small portions of the PROM are used to store instruc tions for initializing and scheduling the operation of the microcomputer Another section is used to store a rou tine which is used if service is to be interrupted The largest portion of the PROM is reserved for the pro gram which monitors the various sensors on a regular schedule calculates the positions of the arm limbs and if necessary provides alarm signal and or provides an automatic shutdown and disconne
34. shows the horizontal orientations of the limbs 10 and 15 when the connecting device 18 is located at each one of the intersections between the planes 27 28 29 and 30 If for example we consider the connecting device 18 when at the intersection of planes 28 and 30 any increase in the slew angle f without a contraction of the arm would take the connecting device 18 beyond the plane 30 Although the vertical components of stress on the tanker manifold beyond the plane 30 would be no greater than if it were located at the intersection of planes 28 and 30 the lateral component of stress parallel to the vertical face of the jetty 23 would be increased and therefore the total combination of stresses would be unacceptable Since the tanker manifold faces toward the tanker rail this lateral stress component constitutes a shearing force and bending moment which can damage the manifold In order to provide the desired indication when a connecting device 18 moves outside the three dimen sional operating envelope defined by the planes 27 28 29 30 33 and 34 sensors are arranged to monitor the angle d FIGS 3 and 7 to provide an indication of the vertical orientation of the limb 10 relative to the riser 14 the angle g to provide an indication of the vertical orientation of the limb 15 relative to the riser 14 and to indicate the slew angle f FIGS 2 and 7 The sensors may comprise a variety of transducers for example potentiometers absolute s
35. t signals 4 205 308 11 cause one of the sensors to be coupled through the multiplex switch 49 to the input lead of the A D con verter The A D converter 50 responds to the IC signal with a busy signal and starts the process of converting the analog data signal into an 8 bit binary signal When the conversion is complete the busy signal disappears and the processor 41 directs an OE output enable signal to the converter 50 The converter responds by delivering the 8 bit binary data signal to the processor 41 and the processor stores the data signal in the data memory 42 FIGS 5 6A for later use in calculation of the loading arm position This process is repeated for each of the sensors with the first data signal being re ceived from the supply voltage source at the beginning of each of the reading cycles The value of the supply voltage from the terminal 54 FIGS 6B 6C is retrieved by the processor 41 and the binary value compared with a binary value representing the standard value of the supply voltage Any variation from this standard value is stored in the data memory 42 and used by the processor 41 to correct readings from each of the angle sensors PI PN As can be seen in FIG 6C when the supply voltage at the terminal 54 changes from the standard value the signal voltage at the sensor output terminal 53 changes by a corresponding amount and could produce a false value of the sensor angle However the correction generated
36. t which is available directly from the processor One such I O expander which can be used in the present circuitry is the 8243 also built by the aforementioned Intel Corpo ration Details of the 8243 I O expander may be found in the aforementioned MCS 48 Microprocessor User s Manual Signals from the angle sensors P1 PN and from the supply voltage 45 are coupled to a plurality of input leads on a multiplex switch 49 These signals are cou pled one at a time through the multiplex switch 49 and applied to an analog to digital A D converter 50 which changes the analog signals into 8 bit digital sig nals for use by the processor 41 The multiplex switch 49 includes a pair of analog switches 49 495 FIG 6B each having a plurality of input leads and a single output lead Selection of the input signal to be coupled to the output lead is made by control signals applied to the select control leads A B C D and I of each of the analog switches One such analog switch which may be used is the CD 4067BE made by the RCA Corporation and details of these switches may be found in the RCA CMOS Manual The A D converter 50 includes a single input lead which receives analog signals and a plurality of output leads which deliver corresponding 8 bit binary signals The converter starts the conversion process when a signal is received on the IC or initiate conversion lead During the time that the conversion is in process the converter 50 devel
37. tentiometer were to change the micro processor 41 would obtain a false value for the position 4 205 308 9 of the limb To prevent this from happening the voltage from the terminal 54 is coupled to the processor 41 and compared with a standard value so that a correction can be calculated by the processor if the value of the supply voltage at terminal 54 should change and this connec tion is used to correct the value from the terminal 53 A signal level control 58 can be used to adjust the value of the analog signals at the input of the A D converter and thus compensate for any changes in oper ating characteristics of the circuitry of FIGS 6A 6B and or for changes in power supply voltage This ad justment is usually made soon after the equipment is turned on but it may also be made at other times The adjustment is accomplished by coupling a voltage such as 12 volts from a supply voltage source 45 FIGS 5 6B through the analog switch 49a to the input of the A D converter 50 and adjusting the signal level control 58 until the processor 41 receives a predetermined stan dard signal such as all binary 1 s from the converter If the signal from the converter 50 is less than the standard value by a predetermined amount the processor 41 causes the I O section of the data memory chip 42 to provide a warning signal to energize a light emitting diode or LED 59 The control 58 is then adjusted until the LED 59 is deenergized Next th
38. th its axis in alignment with the vertical axis 13 so that the lower end of the elbow 14a is rotatable about the axis 13 The sheave 19b is mounted for rotation about the axis 12 independently of the inboard limb 10 and its elbow 10a An encoder support bracket 79 has one end thereof connected to the sheave 195 and the other end supports an absolute angle encoder P2a which is aligned coaxi ally with the horizontal axis 12 Another support bracket 80 mounted on the flange 75a supports an absolute angle encoder Pla that also is coaxially aligned with the axis 12 A third support bracket 81 extends upward from its mounting on the outer portion of the riser swivel joint 76 and supports an absolute angle encoder P3a that is coaxially aligned with the riser s vertical axis 13 A magnet support bracket 82 mounted on the elbow 14a supports a pair of magnets 85a 85b which are positioned immediately below and adjacent the encoders P2a Pla respectively Another magnet support bracket 83 likewise mounted on the riser elbow 14a supports a magnet 85c which is positioned adjacent the encoder P3a The absolute angle encoders Pla P2a P3a and the magnets 85 856 85c operate in the following manner A ferrite inner portion of an encoder is always aligned 4 205 308 13 toward the magnet which is mounted adjacent the en coder so that as the encoder is rotated about a center axis the encoder provides an output signal representa tive of the a
39. the alarm system so the alarm devices will be energized when any of the connecting devices in a bank of arms move outside the safe operating boundaries The clock generator in the processor 41 provides clock pulses which cause the processor to move through the program sequence starting with step 1 The program which is contained in the program mem ory 37 is moved to the processor 41 by the procedure of having the processor 41 send a fetch command over the lines W1 W15 to the PROM 37 The PROM sends the program instructions one at a time starting with in struction f 1 from the program memory to the proces sor 41 where they are executed The instructions in the program call for the processor to retrieve and store the data which is provided by the switches S5 S14 FIG 6B by the supply voltage 45 and by the angle sensors P1 PN In order to retrieve this data the processor sends out a data request signal and the address of one of the input ports in the com puter to which the data is to be sent If the data is to be received from one of the switches 55 514 the signal is sent from one of the input ports P10 P23 FIG 6A To receive data from any of the angle sensors PI PN or from the supply 45 the processor sends out an IC initiate conversion signal to the A D converter 50 FIGS 5 6B and sends select signals through the mem ory and I O expander 42 FIG 6A to the select lines 27 32 of the analog switches 49 495 The selec
40. y variations in sea level variations in the height of the tankers and variations in the height of a tanker mani fold above sea level as the tanker is filled The freedom 4 205 308 20 25 35 40 45 50 55 60 65 4 of movement between the planes 29 and 30 FIG 2 is accounted for by allowable movements of the tanker parallel to the jetty To accommodate these movements it must be possible for the connecting device 18 to reach a manifold located anywhere within the three dimen sional operating envelope defined by vertical planes 27 28 29 and 30 and horizontal planes 33 and 34 The phantom representations of the arm in FIG 1 show the orientation of the limbs 10 and 15 when the arm is located in a vertical plane through the riser 14 and perpendicular to the edge of the jetty and when the connecting device 18 is in each of the four corners of the rectangle defined by planes 27 28 33 and 34 It will be appreciated that if an indication is to be given when the connecting device 18 moves beyond the plane 28 for example it is necessary to monitor both angles g and d FIG 3 If only one of these angles is monitored it would not be possible to define the plane 28 so as to determine when the connecting device 18 moves be yond this plane As should be readily apparent when the arm is connected to a tanker manifold the stress on the manifold increases as the connecting device 18 moves away from the jetty 23 FIG 2
41. y referring to FIGS 6A and 6B where FIG 6A comprises the computer section of the circuitry and FIG 6B comprises the input output and analog digital converter sections of the circuitry The leads in FIGS 5 6A and 6B represent single wires when these leads include square corners and represent cables having a plurality of wires when rounded corners are shown in the leads In the embodiment of the invention diagrammatically depicted herein a program memory 37 FIGS 5 6A stores the length of each of the limbs 10 15 the X Y Z coordinates of all of the safe boundaries for the connect ing device 18 and also a program to be executed by the processor A plurality of angle sensors PI PN FIGS 5 6B provide elevation and slew information to a mi croprocessor 41 FIGS 5 6A which stores this infor mation in a data memory 42 and a plurality of status input switches 38 supply status data to be loaded into the data memory 42 The microprocessor 41 includes a small scratch pad memory which can be used to temporarily store data to be processed an accumulator which performs the oper ations of manipulating data and a program counter which stores the address of the step of the computer program that is being executed One microprocessor which may be used in the circuit of the present inven tion is the 8035 which is built by the Intel Corporation Santa Clara Calif Details of the 8035 processor may be found in the MCS 48 Microcomputer U
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