Formation Control

for Platoons of

Autonomous

Vehicles

Student : Chouaieb Nemri

Supervisor : Prof. Cédric Pradalier

OUTLINE

Introduction

State of the Art

Problem statement

Suggested control solution

Simulation Results

Conclusion

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES2

INTRODUCTION

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES3

INTRODUCTION

Safety Highway Capacity

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES4

Source : http://www.toyota-global.com/innovation/intelligent_transport_systems/images/The_Future_of_Mobility.pdf

INTRODUCTION

Eco-friendly Less workforce

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES5

WHERE ARE WE NOW?Source : IHS

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES6

STATE OF THE ART

Control law based

on local/Global

platoon data?

Vehicle commands

computed on

central computer?

Platooning

Decentralized

Global Local

Centralized

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES7

Platooning approaches

STATE OF THE ART

Accurate tracking.

Depends on whole

convoy data.

Communication delays

– Packet Loss – Data

processing and

transmission time

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES8

Centralized & Global decentralized architectures

STATE OF THE ART

• No communication

needed

• Based exclusively on

proprioceptive and

exteroceptive sensors

• Not as accurate as

Global or Centralized

approaches

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES9

Local decentralized architectures

PROBLEM STATEMENT

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES10

Lateral error propagation – proportional controller (video)

Lateral error getslarger as we

consider laterRobots in the convoy

SUGGESTED CONTROL SOLUTION

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES11

© Jano Yazbeck, Alexis Scheuer and François CharpilletUniversité de Lorraine, LORIAInria, MAIA team - FRANCE

SUGGESTED CONTROL SOLUTION

Control Law

Longitudinal

SSC Proportional

Lateral

MemoLAT

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES12

Decoupling control components

SUGGESTED CONTROL SOLUTION

A typical control loop

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES13

The Big Picture

Compute

Longitudinal

Control

Choose target and

Compute Later

Control

Apply

control

laws

Rebelotte

Aquire and save

predecessor’s

position

12

3

4

SUGGESTED CONTROL SOLUTION

Middleware : ROS indigo

Simulation software : V-REP

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES14

Used simulation environment

SUGGESTED CONTROL SOLUTION

IndivMarkersNoKinect

• Detects the alvar

markers and yields

their coordinates in the

camera frame

Tracker

• Adding new

points to the path

• Coordinate transform

from previous frame to

current frame

everytime we update

odometry

• Delete old points

Controller

Computes

and applies

contol laws

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES15

SUGGESTED CONTROL SOLUTION

Tracker

•Sync_odo_cb : (left/right wheel encoders)

- Odometry

- Path coordinate transform

- delete old points

•Ar_cb : (AlvarMarkers)

- Coordinate transform from camera frame to robot frame

- add new point to path

Controller

•List_cb: (custom pointlists msg)

- Computes current distance from predecessor.

- Selects target point for MemoLAT

•control_cb : (Timer 10 ms)

- Longitudinal control : proportional law

- Lateral control : Modified MemoLAT (Video)

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES16

SUGGESTED CONTROL SOLUTION

Limited camera’s angle of view.

Robots get lost when miss the AlvarMarkers

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES17

Solution : Combining 2 behaviours. MemoLAT & keeping the markers in the visible zone. (cost : less accuracy)

w = alpha * keep_visible + (1-alpha) * MemoLAT

SIMULATION RESULTS

Improved accuracy (Videos)

Angular error as a function of time

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES18

SIMULATION RESULTS

Small d_l

• Small lateral

deviation.

• BUT creates

oscillation around

small curvature

paths

Large d_l

• Large lateral

deviation for high

curvature paths

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES19

Effect of establishment distance

We have no analytic relation in order to dynamically set a suitable value for

CONCLUSION

Platooning is awesome !

Lateral and longitudinal controls can be decoupled

We suggested a high level controller. It is applicable to all kind of mobile robots

Experimantal trials, setting dynamically the establishment distance…

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES20

THANK YOU.

4/27/2015CHOUAIEB NEMRI – FORMATION CONTROL FOR PLATOONS OF AUTONOMOUS

VEHICLES21

Questions ?