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Control System for Scale Model PRT Vehicle Advanced Transit Association Annual Technical Meeting January 13, 2013 College Park, Maryland Robert Johnson R. E. Johnson Consulting Rockville, Maryland www.REJConsult.com Slide 2 Model of PRT Vehicle that Steers Itself on a Flat Surface Ultra 2getthere Masdar Vehicle www.REJConsult.com2 Slide 3 Why Use Scale Model to Develop Control Software? More realistic than pure simulation Avoids assumptions that are not physically possible Can demonstrate system operation Suitable for computer vision based control, which is independent of scale Modern electronics are small enough to fit inside 1/12 th scale model 12.5 in (32 cm) long www.REJConsult.com3 Slide 4 PRT Scale Model Right Side www.REJConsult.com4 Slide 5 PRT Scale Model Showing Lateral Sensor Ahead of Front Wheel www.REJConsult.com5 Slide 6 External Appearance www.REJConsult.com6 Slide 7 Autonomous Vehicle with Three Levels of Computer Control Central control (like taxi dispatcher, not safety related) On-board computer vision system running Linux -- provides longitudinal control On-board microcontroller (only vital system) Monitors vision computer Provides lateral control by using sensor to measure distance to sidewall Controls steering, drive motor, brakes, etc. www.REJConsult.com7 Slide 8 Lateral Control Demonstration www.REJConsult.com8 Slide 9 Updates Since Last Years Technix Finalized vehicle design except vision system Electro/mechanical aspects of vision system complete (power supply, etc.) Achieved basic vehicle following using netbook as vision computer www.REJConsult.com9 Slide 10 Small, Inexpensive, Low-Power ARM Computers for Vision Processing www.REJConsult.com10 Slide 11 Small Multi-Core ARM Computers for Less Than $200 with Linux Support Pandaboard Texas Instruments 4.5x4.0 (114x102 mm) i.MX6 Q Sabre Lite Freescale Semiconductor 3.3x3.3 (83x83 mm) www.REJConsult.com11 Slide 12 Current Status of Vision-Based Longitudinal Control OpenCV vision software operational on x86 PC running Ubuntu Linux Webcam support not an issue for x86 Ubuntu Basic vehicle following using color tracking of target on rear of lead vehicle As temporary measure, communicate with microcontroller by changing brightness of portion of PC display www.REJConsult.com12 Slide 13 Vehicle Following www.REJConsult.com13 Slide 14 Future Work Requires Mostly OpenCV and Linux Skills Port existing software to small ARM computer Establish suitable communications link between vision computer and microcontroller Merging Station operations www.REJConsult.com14