Personal Rapid Transit Scale Model Advanced Transit Association Annual Technical Meeting January 21, 2012 College Park, Maryland Robert Johnson R. E. Johnson Consulting Rockville, Maryland

Model of PRT Vehicle that Steers Itself on a Flat Surface ULTra 2getthere Masdar Vehicle

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 scale model

Model Uses Distributed Control System Fully autonomous vehicles Three computer systems –Central control –On-board computer vision system –On-board microcontroller

Central Control Like taxi dispatcher, not safety related Radio link to vehicles Handles empty vehicle routing Supports operator monitoring of system and operator intervention if necessary Could be Windows or Linux PC Scale Model uses C# program on Windows PC

On-board Computer Vision System Detects vehicles ahead in same lane Detects vehicles at merges and in stations Detects trespassers / foreign objects on roadway Could provide lateral guidance “Soft” real time system Probably would use Linux as operating system

On-board Microcontroller Operates steering, drive motor, brakes, doors, etc. Monitors computer vision system Microcontroller is a vital system Scale model uses 32-bit ARM Cortex M made by NXP Semiconductors

Updates Since Last Year’s Technix Changed scale from 1/9 to 1/12 Currently have two operating vehicles Vehicles can drive themselves around test loop

Change to 1/12 Scale Vehicle is 12.5 inches (32 cm) long Can still hold new, smaller computer-vision processors that have recently become available More convenient size, especially test track

Last Year -- 1/9 Scale Vehicle

1/12 Scale Vehicle -- Right Side

1/12 Scale Vehicle Elevated View of Front

1/12 Scale Vehicle – Left Side

1/12 Scale Vehicle -- Left Front

1/12 Scale Vehicle on Half Loop

Future Work Refine and complete existing vehicles Computer vision Vehicle following Merging Station operations