Merge-by-Wire: Algorithms and System Support Vipul Shingde, Gurulingesh Raravi, Ashish Gudhe, Prakhar Goyal, Krithi Ramamritham {vipul.shingde,gurulingesh,ashish.gudhe}@gmail.com, {prakhargoyal,krithi}@cse.iitb.ac.in

Indian Institute of Technology Bombay Automatic Merge Control (AMC)

Implementation

• Automated merging of vehicles at road intersections

AFS and HoL were implemented using DSRC based AFR-CS protocol for inter-vehicle communication

• Determines merge order of vehicles • Safety-Critical Application

Merge Region > =S

Road1

Primary Aim • Safety Secondary Aim • Throughput ↑ • Fuel Efficiency ↑ • Traffic flow ↑ • Driving Time to Intersection ↓ • External control time ↓

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Vehicle movement direction

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Infrastructure Node

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Constraints • Precedence Constraint: No vehicle overtakes its leading vehicle • Mutual Exclusion Constraint: No two vehicles are present in the intersection region at any point of time • Safety Constraint: Safe distance is always maintained between consecutive vehicles on same road, before they enter merge region • Limits: Vehicle velocity and acceleration

HighHigh-Level Design of AMC: Dual State, Triple Zone Approach

Area of

SM state

SD state

Experiments on Robotic Vehicular Platform FireBird-III, the robotic vehicular platform developed at IIT Bombay was used for conducting experiments & had following features: • Obstacle detection range: 30cm • Wireless radio module • Closed-loop controller(s)

Merge Region

Magnetic

Lane 1

Belt

SD to SM state

Interest

(AoI)

SD state

HoL v/s AFS: DTTI and external control duration • AFS can handle higher vehicle density • HoL offers higher vehicle autonomy

Experimental Results

e2

Zone 1

Lan

Zone 2

• Accuracy in maintaining desired safe distance AFS maintains safe distance with 100% accuracy

Zone 3

Dual State Vehicles operate in either of two states: •SD (Safe Distance) - Adaptive Cruise Control - Local Mode of Control •SM (Safe Merge) - AMC decides trajectory - External Mode of Control

Triple Zone Vehicles function in different state in different zone: •Zone 1 - Operates in SM state - Vehicle left untouched •Zone 2 - Vehicle transitions to SM state •Zone 3 - Vehicle in SD state - Stabilize traffic flow

• Average Driving Time To Intersection (DTTI) AFS and HoL produce low DTTI

AMC algorithms 1. Head of Lane (HoL) - Head of Lane is the leading vehicle of the lane - Merging Decision: To select one of the HoL vehicles - Distributed algorithm 2. All Feasible Sequences (AFS) - Centralized algorithm - Needs Infrastructure Node located adjacent to the merge region collects profiles of all the vehicles present in Zone 2 - Considers all feasible merge sequences. Chooses sequence with minimum Driving Time to Intersection (DTTI) 3. Position Virtual Vehicle - Virtual vehicle is an image of actual vehicle from other lanes

For details see: Merge-by-Wire: Algorithms and System Support., Vipul Shingde, Gurulingesh Raravi, Ashish Gudhe, Prakhar Goyal, Krithi Ramamritham, In IEEE Real Time Systems Symposium 2008.