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1. Pavement Thickness Priority Control Slope Control The screed s slope is controlled automatically to the set cross slope using inclination sensors Block diagrams of pavement thickness priority control and side level control are shown in Figure 6 and Figure 7 No 1 Height Sensors No 2 Height Pavement Flat Sensors Surface 6 Reference Line Differ Calcu Line Created ence from No 1 Incli A D I O lated Created Reference nation Sensor Con In Line ver ters No 3 Height ter face Sensors Data Memory ba No 4 Height Sensors No 2 Incli nation Sensor Running Dis tance Sensor Pivot N screed Figure 6 Block Diagram of Pavement Thickness Priority Control No 1 Height Sensors Operating Unit A D 1 0 Average Difference No 2 Height Con In Pavement Existing between Target Sensors ver ter Thickness Pavement Pavement Thickness and from Actual Thickness No 1 Incli nation Sensor f Data Memory Running Dis 1 I 1 i 1 l ter face T Thickness I 1 1 l tance Sensor Operating Unit A D 1 0 Target Control Correction No 5 Height Con In Value of Level of of Grade Sensor ver ter Grade Grade Control ter face Control Control Target Sensor Sensor Value Figure T Block D
2. been automated through the use of sensors and computers 2 1 Machine Initial Settings The attack angle of a screed plane difference and other settings were previously made based on the instinct of skilled operators Througk the use of memory card not only is it possible to make these settings automatically but the correct screed surface pressure crown volume and pivot cylinder position can be obtained automatically Through a microcomputer the paving material thiekness and width crown equipment and finishing speed are input to the memory card This card is then inserted into the card slot and a series of machine settings is accomplished automatically A concept diagram and control block diagram are shown below Figure 1 Figure 2 The following items are set automatically by the IC card e Screed Surface Pressure IC card Fine Graided Asphalt Concrete 13 Paving Thickness 5 cm Paving Width 3 5 m e Attack Angle a Crown Volume v20 e Level Difference Speed 3 0 m min e Pivot Position e Crown Volume Powered Thickness Control Power Plane Difference Control z Screed Inclination Angle Sensor Body Inclination Angle Sensor Figure 1 Concept Drawing of Initial Automatic Settings Body Inclination Angle Sensor 00 Left Screed Crown Sensor i L i i i Inclination Angle g A D Operat I O Each Sensor 1 Con i
3. material from dump truck the machine s height is made adjustable Rear Axle Figure 11 Suspension System Diagram 3 2 Running Speed Control The asphalt finisher has two modes of running One is for driving the machine and the other is for paving operations In paving operations the engine speed is controlled at a constant level by an electronic governor The running speed is sensed by a proximity sensor which counts the number of gear teeth on a gear mounted on the hydraulic motor used to drive the asphalt finisher during running Signals from this sensor are fed back to control the swash plate in the hydraulic pump so that the finisher is driven at a constant speed The swash plate is controlled in this system by a servo valve This servo valve has a first stage which uses a nozzle flapper type pilot valve to output pilot pressure proportional to electrical command signals It has a second stage with a double spool structure which acts as a swash plate angle control valve The feedback signals pass through a PID controller and current amplifier and drive the servo valve A block wiring diagram of the operation system is shown in Figure 12 Reverser EDC Valve Amplifier Working E p gt e Speed si control oi eee Create Proximity Sensor Gear Transmission Figure 12 Here we would like to explain a little about the electronic governor This governor controls both the engine speed and the pump d
4. L ENVIRONMENT AND HARMONY WITH THE The measures shown in the following table were introduced particularly to banish the three D s difficult dirty dangerous image of the conventional asphalt finisher Comparison Item a Advanced Asphalt Finisher Ordinary Asphalt Finisher Cabin cabin included Delux passenger car like None operator s seat equipped with FM AM radio CD player video deck etc Lubrication Cleaning is done by pressing a switch at Each part is lubricated Cleaning the control panel and lubrication is and cleaning is done by ne automatically hand Noise Level Ultra low Noise Construction Ministry Low Noise Construction srandards Ministry standards Design Color Designed to fit into an urban setting 3D image i 6 MEASURES FOR PERMITTING CREATIVE PAVING WORK In order to expand paving operation control and the work range ete the measures shown in the following table were introduced Ordinary Asphalt Finisher Comparison Item Advanced Asphalt Finisher The operator listens to the supervisor then sets the machine from his memory Machine settings to match work conditions Set automatically using IC cards Created by office personnel Creation of work Printed out from an IC card data Range of Paving The screed surface pressure and heater Material temperature can be changed freely an
5. Lock Switching Priority Valve Steering 2 ae Ea pane Neutral Sensor Limit Switch He Neutral Sensor Limit Switch Front Axle Figure 13 4 EASY OPERATION MEASURES In order to make it possible to operate t one operator sitting in the cabin with no mor of a passenger car driver introduced Comparison Item Advanced Asphalt Finisher Driving Operation A liquid crystal color display touch panel voice response etc minimize the number of switches and guide driving Lock Cylinder i Rear Axle Steering System Diagram he asphalt finisher with e than the senses required the measures shown in the following table were Ordinary Asphalt Finisher The user s manual must be read and memorized and depended on in order to operate the machine Confirmation of dead corners work condition Checked from the operator s seat using a TV monitor Communications with outside Communications by microphone and speaker Steering Turning radius is cut in half compared to previous machines using 4WS making machine setting easier Must go to the check points and check Direct voice communications 2WS Vehicle height during work and when driving Set automatically to be low during work and high when driving Fixed d 5 MEASURES FOR AN IMPROVED OPERATING ENVIRONMENT SOCIA
6. The 9th International Symposium on Automation and Robotics in Construction June 3 5 1992 Tokyo Japan Development of Advanced Asphalt Finisher Fumio Goto Takasaki Factory Niigata Engineering Co Ltd 730 Munataka Gunma Machi Gunma Ken Japan 370 35 Tohru Saitoh Technical Research amp Development Division Nippon Hodo Co Ltd 19 11 Kyobashi 1 Chome Chuo Ku Tokyo Japan 104 Abstract More than half a century has passed since the asphalt finisher was developed Over the years since that time this machine has been made larger and the performance of its various parts has been improved but its image as a complicated machine requiring many special skilled operators has not changed The purpose of this paper is our development of an asphalt finisher in which the operations that required the experience and intuition of skilled operators in the past are performed automatically by various types of sensor and computers creating a high value added machine which eliminates the previous three D s difficult dirty dangerous image of the typical construction machine and in its place creates a new three C s clean comfortable creative image while at the same time possessing the qualities of a user friendly machine through the use of robotics 1 INTRODUCTION The building of Japan s social capital is steadily advancing and the building of roads is also progressing steadily Under the current conditions the age of experienced personne
7. d the range of paving materials which can _ be used is wide Screed surface pressure and heater temperature cannot be changed T CONCLUSION The integrated systems to which each of these devices has been applied were submitted to the Construction Equipment Exhibition in Kobe or 91 Kanto New Technology Fair with successful results In addition machines equipped with some of these devices will be developed into marketable products in the near future In order to achieve this development great reliance was placed on electronics technologies being developed at the present time Therefore it is possible that a still more advanced machine can be developed when higher precision sensors high speed processor elements and new materials etc are developed In addition thought is being given to the introduction of information processing functions which would carry out the collection and analysis of various types of data and linking of data from measuring operations and data from paving operations etc which are necessary to automation of work control At the present time development of some of the elements needed to further incorporate robotics into the machine is proceeding There are also other functions being demanded by users which need to be incorporated and still more improvements are necessary We would like to take this occasion to thank all those who cooperated with us in the development of this equipment whether
8. e then he would through experience and intuition extend or retract the pivot cylinder accordingly to adjust the paving thickness With the new machine all the points caught previously by the operator s eye are caught by contactless sensors and the paving thickness is adjusted automatically A layout diagram of the devices used in this system and an example of the controls involved are shown in Figure 5 and Table 1 respectively Computer Pivot Cylinder Leveling Arm Measuring Arm Side Level Arm SES No 2 Inclination Sensor ALLA 3 and No 4 Height Sensors jell Paving Surface No l and No 2 Height Sensors No 1 Inclination Sensor No 5 Height Sensor Control Paving Thickness Estimation Line Road Surface Reference Target Paving Thickness Figure 5 Layout Diagram of Paving Thickness Automatic Control Device Table 1 Example of Paving Thickness Control Method Pavement Thickness Control Method Outline of Control Using an ultrasonic sensor the screed is controlled with the object reference as the reference The screed can also be controlled automatically to set the pavement thickness Pavement Thickness Feedback Control Side Level Control Using ultrasonic sensors mounted on both sides of the vehicle the base course is made the reference and the screed is controlled automatically to the pavement thickness
9. iagram of Side Level Control 2 4 Supply of Paving Material The amount of paving material needed to be supplied in front of the screed was determined by an operator visually and the supply volume was adjusted using a dial and switch manually in the past This has been replaced by the use of non contact sensors as shown in the figure below Signals from these sensors are used to control the speed of each conveyor automatically An example of a layout diagram of the devices in this system is shown in Figure 8 The block diagram for one example of the control for this system is shown in Figure 9 Electromagnetic Proportional Control Valve Mixture Level Sensor 1l Mixture Level Sensor 2 Stationary Screw Ee 7 BEER unl screed Gate Extendable Screw Right Screed Figure 8 Layout Diagram of Paving Material Automatic Supply Control Equipment Mixture Level c Sensor l A D Amplifier Switch Hwedae Con Mixture Level ver wg O Propor 1 Sensor 2 ter 1 0 D A g tional In Valve Start Stop ter Input Device face Running Switch Screw Rear Propor UP DOWN Switch Valve Screw Rotation cd UP DOWN Switch Figure 9 Paving Material Automatic Supply Control Equipment Block Diagram Feeder Screw Auto Off Manual Switch ee ee rane mr serene ic ei pros eo A Balas ae
10. ickness T when the screed is in position B when the machine position is in state 2 first measure the difference between the valleys and peaks in the base course at points B and C with the machine position inostate 1 Since H1 H2 M tan 2 No 2 Height H2 H1 M tan 0 Sensor In the right figure the formula is given below Hatre 0 Ho T T tan Screed According to this formula the paving thickness at point B can be calculated to be Tys Ho o M tan Ho d6 Determined from the previous formula Furthermore at this time Since 62 is measured and calculated as Shown in the above figure if the screed is moved to point C next time it will be possible to measure and calculate the pavement thickness at point TAN Displayed at Operator s Seat Computer Leveling Arm Measuring Arm Paving Surface ee LRN No Figure 3 Layout of Pavement Thickness Measuring and Display Device Display No 1 Height i i Paving Sensor 1 Thickness No 2 Height i Sensor Inclination Sensor Running Distance Meter Figure 4 Pavement Thickness Automatic Measurement and Display 2 3 Adjustment of the Paving Thickness Generally the operator would use a gauge stick and measure the paving thickness and would take visual measurements of the amount of ground clearance of the screed when it was moved or the height of structures along the sid
11. in government or private sector Example of Advanced Asphalt Finisher 4 sri UN ili iti ini cam
12. ischarge volume in accordance with the amount that the accelerator pedal is depressed realizing A M C control AutoMotive Control This system prevents engine stall and controls the engine speed at a constant level during paving operations as mentioned earlier Various A M C controllers and accelerator controller are provided to accomplish this control The accelerator controller controls the governor with a DC servo motor in accordance with the amount the accelerator pedal is depressed The movement of the governor is detected by a differential transformer Signals from this transformer are fed back to the accelerator controller so that the amount of accelerator pedal depression and the operating volume always match 3 3 Steering Four wheel steering 4WS in which both the front and rear wheels form the steering angle is used This system is also designed so that same phase and different phase running can be done In this way the turning radius can be reduced to 1 2 that of the operation range making it extremely maneuverable in tight turns and by joint use with same phase steering machine settings are made more easy and operability is improved A diagram of this system is shown in Figure 13 next page sce ee non tet cee merits sncarettianeiceintinae E b oisiacts Lalas a rin RR ome gem Front Steering YS Crab Steering _ Orbitrol Built in Mode Switching Valve a ee
13. l for the ever increasing road paving work is advancing At the same time there are fewer and fewer people who are skilled at this work and this problem is complicated by the general shortage of labor At the same time workers are expressing the desire to be free from hard and dangerous labor and have an improved working environment Under the circumstances we established the following development concepts 1 A machine with a man machine interface i e a machine which can be operated easily like a passenger car 2 Highly automated machine eliminating troublesome jobs and saving Skilled workers 3 The machine should harmonize not only with the working environment but also with the social environment 4 The machine allows an operator to be creative in doing his job With the above development concepts we set out to develop a next generation asphalt finisher which uses various sensors memory cards and computers mounted a cabin increased its moving speed incorporated 4WD and 4WS and other high technology systems The following pages describe the method we used 2 AUTOMATION METHOD sais e ELBE ie The initial setting of the machine before laying asphalt mixture measurement and adjustment of paving thickness accounting for most of operatins during laying and supply of paving materials at the front of the screed all of which had previously been considered to be done through the human judgment of experienced operators have
14. ng Inter Adjust E icik g 3 verter Unit face er ig cree Inclination Angle Sensor 02 i Pivot Sensor i Data Plane Difference i Memory Sensor i 1 1 i i Input Device IC Card etc pee a pee EER Raat ate a a eS RE HS ms mre a 4 Figure 2 Block Diagram of Initial Automatic Settings 2 2 Setting the Pavement Thickness and Estimated Pavement Thickness In the past a measuring device known as a depth gauge was used The operator would insert the gauge stick into the pavement and measure This has been replaced by a contactless measuring system which Simultaneously displays the depth digitally for the operator and also displays a graph of the transition in the pavement thickness In addition it was difficult in the past to know how the pavement thickness would change over time but with the new machine sensors are used to determine automatically the condition of the base course which is being paved as well as movements of the Screed and display an estimated pavement thickness These data are displayed in real time on a color display at the control panel as shown in Picture I FERADU K E The layout diagram of paving oie thickness measuring device and a block diagram are shown in Figure 3 and Figure 4 The theory used for measuring the pavement thickness is as shown below State 1 Inclination Sensor Measuring Arm Miaa ew 8 8 aS ELT To measure the paving th
15. ra nieces 2 5 Screed Heater Temperature Adjustment In the past the combustion system was the direct firing type which was controlled manually by the operator However with new system by setting the temperature in accordance with the working conditions the temperature of screed is maintained at a constant level automatically Also a hot air fan heater system is used so that paved surface texture is improved heating is made constant and power and energy are saved A diagram of this system is shown in Figure 10 LPG Tank PID Control 24 VDC Screed Unit LA Flame ro a ae Screed Plate Figure 10 Automatic Temperature Control and Hot Air Screed Heater System Diagram 3 DRIVE SYSTEM 3 1 Suspension One measure taken to harmonize the asphalt finisher with the environment was to raise the maximum speed from the previous 16 km h to approximately 40 km h To do this it was necessary to provide the machine with riding comfort comparable with a passenger car so a hydropneumatic suspension was adopted A hydropneumatic suspension consists of hydraulic cylinders accumulators shut off valves check valves and other devices The vibrations from the road surface are absorbed by the accumulators A diagram of this system is shown in Figure 11 This suspension system is constructed so that its functions can be rendered inactive during paving operations And at the same time in order to make it easier to receive

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