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

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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

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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

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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

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Simulation represents guideway as straight segments alternating with circular arcs

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

• End-of-line station

• Center platform station

• “T” Intersection

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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

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Vehicle in Low Priority Lane Yields

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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

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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)

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(Very Short) Shuttle UsingAutomated Road Vehicles

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End-of-Line StationOutbound paths

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

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Path-Crossing ConflictVehicle Leaving Berth Yields

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Merge ConflictVehicle From Berth Nearer Exit Yields

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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

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Vehicles Crossing Paths

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

OR

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Simulation of Complete Shuttle

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

OR

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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