Micro-Simulation of Automated Vehicles with Minimal Central Control

Micro-Simulation of Automated Vehicleswith Minimal Central Control

Advanced Transit Association Annual Technical Meeting

January 12, 2008

Washington, DC

Robert Johnson

R. E. Johnson ConsultingRockville, Maryland

www.REJConsult.com

www.REJConsult.com 2

Different Types ofAutomated Transit Vehicles

• Track based

– Run on special track that provides lateral guidance and power (most People Movers are in this category)

• Automated Road Vehicles

– Steer themselves along a flat surface without mechanical guidance

– Have a self-contained power supply

– Max speed 20 - 25 mph (32 - 40 kph) on exclusive roadway


Examples ofSmall Automated Road Vehicles

CyberCab: proposed by 2getthere which operated the first public ARV

ULTra: scheduled to begin service in 2009 at Heathrow airport, London


Presentation: Three Related Topics

• Micro-simulation model for Automated Road Vehicles

• Using the model to demonstrate a simple vehicle-based control strategy

• Simulation of a shuttle application


Simulation represents guideway as straight segments alternating with circular arcs


Library of Special Guideway Elements(in Various Stages of Development)

• End-of-line station

• Center platform station

• “T” Intersection


Vehicle-based Control System:How to Handle Conflicts

• Vehicles know the complete layout of the system, and know exactly where they are

• At each merge or crossing point, one lane always has priority

• If a vehicle is in the low priority lane, it uses its sensors to scan the high priority lane, and yields if a vehicle is detected


Vehicle in Low Priority Lane Yields


Vehicle-based Control System (cont.)

• Vehicles use sensors to watch for objects in their path (another vehicle or foreign object)

• If unexpected object detected, vehicle stops and notifies human operator at central control

• Central control computer:

– Assigns destinations to vehicles

– Holds vehicles at stations to smooth system flows

– No safety-related functions


Example Application - Shuttle

• Two-way guideway with a station at each end

• Six-passenger, shared vehicles

• 5 second minimum headway

• Maximum passengers per hour per direction

– 4320 theoretical (6*3600/5)

– Practical maximum is probably between 1000 and 2000

• Better than conventional people mover shuttle since can give riders very short wait times (say, 60 sec max)


(Very Short) Shuttle UsingAutomated Road Vehicles


End-of-Line StationOutbound paths


End-of-Line StationInbound paths - Vehicles back into berths


Path-Crossing ConflictVehicle Leaving Berth Yields


Merge ConflictVehicle From Berth Nearer Exit Yields


Merge Conflict Leaving Station

Click image at left to play video if .WMV file was downloaded

OR

Press button below to play video from web

http://www.autoroadvehicles.com/downloads/atra-20080112-s16-merge.wmv


Vehicles Crossing Paths


OR


http://www.autoroadvehicles.com/downloads/atra-20080112-s17-cross.wmv


Simulation of Complete Shuttle


OR


http://www.autoroadvehicles.com/downloads/atra-20080112-s18-full.wmv


Conclusions and Future Work

• Vehicle-based control seems feasible, at least in simple systems

• Shuttle systems could be implemented at very low cost, after development of electronics for vehicle

• Next step: develop detailed operating rules for vehicles in T intersections and center platform stations

Documents

Micro-Simulation of Automated Vehicles with Minimal Central Control