integrated chassis control brakenet 2002

Integrated Vehicle Control SystemsIntegrated Vehicle Control Systems

Vehicle Chassis SystemsVehicle Chassis SystemsControl Control

and and IntegrationIntegration

September, 2002September, 2002

Dr. Mark N.W. HowellDr. Mark N.W. Howell

Integrated Vehicle Control SystemIntegrated Vehicle Control System

• IntroductionIntroduction

• Systems IntegrationSystems Integration

• Subsumption ArchitectureSubsumption Architecture

• ExamplesExamples

• ConclusionsConclusions

Presentation OutlinePresentation Outline


• Safety• Predictable behaviour• Responsive Handling • Ride Comfort

• Maximise efficiency & performance of the vehicle• Flexibility, modular, ‘plug and play’ architecture

IntroductionIntroduction


OEMOEMRequirementsRequirements

Based on car type/OEM requirements

select required systems for interaction

Brand DNA Product Differentiation

Performance FeelPerformance Feel

Ease of UseEase of Use

ReliabilityReliability

IntegrityIntegrity

SafetySafety

ComfortComfort


Whole Vehicle Objectives

Braking Steering

Suspension Powertrain

6 D.O.F

Longitudinal Lateral Bounce Pitch Roll Yaw

Characteristics

Safe Predictable Responsive Handling Ride ComfortNVH, Energy, Reliability, Cost ...


• Braking Systems - ABS, TRC

• Steering - AFWS, 4WS

• Suspension - Active, Semi-active, Roll Control

• Drivetrain - Differential/ IVT/CVT

• + Cruise Control, Intelligent/Adaptive Cruise Control

• Yaw moment control, X-by-wire

• Future systems: Collision Avoidance, Parking

• Need a coherent way of integrating systems

The Need for IntegrationThe Need for Integration


• Modular

• Respect IPR of suppliers

• Avoid excessive complexity

• Incorporate fault detection, diagnosis and tolerance

• Open architecture

Design RequirementsDesign Requirements


Subsumption Architecture Subsumption Architecture

Sensors

STIMULUS

COORDINATIONO

Actuators

Behaviour 1

Behaviour 2

Behaviour n

A modular, behaviour based, distributed architecture

Behaviours are layers of control architectures that are event driven

One layer can subsume control over another layer

Higher level behaviour can suppress a lower-level behaviour.


• Distributed Layered Control– Control distributed across parallel layers each with multiple modules

• Behavioural Decomposition– different layers support different ‘task-achieving’ behaviours’ – decomposes into behavioural rather than function units

• Increasing ‘Levels of competence’– Ascending level adds capabilities resulting in higher overall competence.– Higher levels often operate by modulating the activities of lower levels.

• Incremental Construction– incremental control system designing – intermediate architecture tested and debugged before next layer added.

• Conflict resolution and communication between levels– Higher layers subsume the roles of lower ones by suppressing their

outputs and substituting their own.

Key Aspects of SubsumptionKey Aspects of Subsumption


SubsumptionSubsumptionAdvantages

• Modular

• Very flexible

• Robust to system change

• Incremental control design Disadvantages

• Complex overall system with a large number of behaviours

• Verification difficult of overall system behaviour


CollisionAvoidance

StraightLine

Stability

NeutralSteer

ParkingAid

SafetyDistance

from Obstacles

Anti -Dive

Anti -Squat

YawStability

RollStability

RideComfort

LoadTransfer

ForwardSpeed

Layer 4

Behaviour

Layer 3

Behaviour

Layer 2

Behaviour

Layer 1

Behaviour

Layer 0

Hardware

ABS TCSSide SlipControl

ControllableSuspension

DriverSen

sor

and

Info

rmat

ion

Bus

Integrated Layers

Non Integrated Layers(mostly single loop)

Lane Detectionand Tracking

Brakes Engine Transmission Suspension Steering

Subsumption SubsystemsSubsumption Subsystems


Sensors(physical)

Sensors(Soft)

State Estimation/Observers

Near TrafficCondition

Driver ModelTrue Vehicle

Model'Desired' Vehicle

Model

Road ConditionEstimation

Bah

avio

urs

Lane Detection

Sensor and Information BusSensor and Information Bus


Behaviour 4

Behaviour 3

Behaviour 2

Behaviour 1

ACTION

MAX (B1, B2,B3,B4)

Behaviour 4

Behaviour 3

Behaviour 2

Behaviour 1

ACTION

Respond of highestactive behaviour

Response of behaviourwith the highestactivation signal

Behaviour 4

Behaviour 3

Behaviour 2

Behaviour 1

ACTION

Voting based (Neural)

Behaviour 4

Behaviour 3

Behaviour 2

Behaviour 1

ACTION

Fuzzy Rule based

(A)

(B)

(C)

(D)


Scope for Integration - ActuationScope for Integration - Actuation

• 4 Independent Brake 4

• Engine 1+(...)

• Driveline (Transmission/differential) 1,2+

• Individual Wheel Steering 4

• Active Suspension 4

Total : 15+


• Stiff suspension model - nonlinear tyre model

• 7 DOF: Yaw, Sideslip, Longitudinal, Wheel spin + Control States

• Independent wheel braking

• Rudimentary Powertrain (torque demand)

• Active Front Wheel Steer

Simple StudySimple Study


• Integrated Systems

• Non-integrated control

Driver

Throttle Brake Input

Steer AngleInput

Brake torque

Front Steer Angle

Throttle

Low

‘ABS’ Independent Wheel Slip Control

Front Slip angle control

Yaw/ Sideslip

Control

Directional

Control

HighIntermediate

Vehicle

Simple study - levels of behaviourSimple study - levels of behaviour


0 2 4 6 8 10 12 14 16 18 20-10

-5

0

5

10

15

20

25

30

time [s]

sp

ee

d [

m/s

]Vehicle Forward Speed

noctrlS

sigmaS

beta10S

allS


0 2 4 6 8 10 12 14 16 18 20-200

-150

-100

-50

0

50

100

150

200

time [s]

be

ta [o ]

Vehicle Side Slip Angle

noctrlS

sigmaS

beta10S

allS


0 2 4 6 8 10 12 14 16 18 20-4

-3

-2

-1

0

1

2

3

4

time [s]

be

ta [o ]

Vehicle Side Slip Angle

noctrlS

sigmaS

beta10S

allS


0 2 4 6 8 10 12 14 16 18 20-60

-40

-20

0

20

40

60

time [s]

de

lta

[o ]Steer Angle

noctrlS

sigmaS

beta10S

allS


0 2 4 6 8 10 12 14 16 18 20-2.5

-2

-1.5

-1

-0.5

0

0.5

1

time [s]

r [r

ad

/s]

Yaw Rate

noctrlS

sigmaS

beta10S

allS


0 2 4 6 8 10 12 14 16 18 20-8

-6

-4

-2

0

2

4

6

8

time [s]

a lat [

m/s

2 ]

Lateral Acceleration

noctrlS

sigmaS

beta10S

allS


• Technical and commercial considerations restrict the ways that integrated vehicle control systems are implemented in practice

• Limiting total system complexity is a priority

• Layered ‘subsumption’ architectures are particularly applicable to the control implementation, but detailed methodologies are not yet well developed

• Issues of conflict resolution in real-time, may be solved by extending commonly available control techniques

Main ConclusionsMain Conclusions


Any Questions ?Any Questions ?

integrated chassis control brakenet 2002

Automotive

layered control control

behaviour layer

behaviour n

b4 behaviour

neural behaviour

lowerlevel behaviour

vehicle objectives

vehicle flexibility