Driver Assistance System(Lane Keep Assist System)

Akira IihoshiVice-Chairman of JAMA

ITS Technical Committee(Honda Motor Corporation)

Presentation to WP-29 ITS Round Table18/02/2004 Geneva

Honda’s proprietary Driver Assistance System

ACC LKAS

Honda intelligent Driver Support System(HiDS)

Adaptive Course Control system + Lane Keep Assist System

Block Diagram of HiDS

Lane-recognition

unit

Yaw ratesensor

Wheel speedsensor

EPSECU

EPSECU

EPS

Steering angle sensor

Brake, wipers,turn-signals,resume/cancel,headwaydistance setting,LKAS-OFF

Torque sensor

ACC controlunit withbuilt-in

millimeter-wave radar

ACC controlunit withbuilt-in

millimeter-wave radar

Brakeactuator

Brakeactuator

ThrottleDBW

ThrottleDBW

LKAScontrol

unit

EFIECU

EFIECU

CombimeterCombimeter

Operation stateindicator/Warning

VSAECU

VSAECU

CAN

Electric Power Steering

VSA:Vehicle Stability Assist / ECU:Electric Control Unit

Functions of Adaptive Cruise Control (ACC)

(3) Vehicle following(1) Constant-speeddrive

(2) Deceleration (4) Acceleration

Forward Speed 45-100km/hAcceleration ＜　0.08GDeceleration ＜　0.2G

Control Range :(in Japan)

Controlling vehicle speed and headway distance to a preceding vehicle

Outline of Adaptive Cruise Control (ACC)

Millimeter-wave RadarRadar covering

Millimeter-wave RadarRadar covering

Principle Functions

Functions of Lane Keep Assist System (LKAS)

Control Range (in Japan)Forward Speed 65-100km/hLateral G ＜　0.2GRoad Radius　 ＞　R230m

CAMERA

Assistance in providing optimum steering movementto keep the vehicle in the center of its lane.

Lane Departure Warning

Honda Assistance System Philosophy

・To avoid decrease in driver motivation・To maximize the benefits of Assistance System

The Driving Assistance System is under development to reducethe driver’s work load.

Driving AssistanceSystem

Effect and Benefit

Background

Purpose

Reduction workload

Assistance effectexpected

Assistance gainlarge

Decrease in motivation

Operational Principle

Outline of Lane Keep Assist System (LKAS)

C-MOS Camera

LaneRecognition

Desired-pathCalculation

Assistant torqueCalculation

for lane keeping

EPSElectric Power Steering

Highways

Image processing(Road recognition)

Driver’s steering operation

Joint steering between systemand human driver

Assistanttorque

Driver’storque

Desired path

＜80% ＞20%

- Road curvature- Vehicle position

Steering torque

Assistant torque

Driver

Assist/not-assistevaluation

Human Machine Interaction System

Steering

＋

Interaction between Human and System

HiDS

Interaction

Detection

Assistance

It regards the driver’s operation as the driving intentionwhen assisting steering operations.

Outline of Lane Keep Assist System (LKAS)

HiDS Operations (video image)HiDS Operations (video image)

Evaluation of HiDS Effectiveness

Mental Evaluation (Mental Tension)

Physical Evaluation (Steering Torque)

Reduce both physical and mental workloads

Subjective Evaluation (Questionnaires)

Margin Evaluation (Eye Movement )

Physical Evaluation Results Fig-1 PSD of Steering Torque

Frequency[Hz]0.001 0.01 0.1 1 10

0

0.1

0.2

0.3

0.4

0.5

0.6

Effect

Ste

erin

g T

orq

ue

PS

D [

N-m

]

HiDSConventional

small

big

Physical workload is reduced

Steering Torque is reduced

Time [sec]

0 600 1200

0

-5

5

SP

L[m

v]

Fig.2-1 Driver’s Mental Tension

0 600 1200

0

-5

SP

L[m

v]

Time

5

Fig.2-2 Driver’s Mental Tension

Mental Evaluation Results

Mental workload is reduced

Mental tension is decreased

Higher number of tension peaks

SPL: Skin (electric) Potential Level

(Conventional) (Using HIDS)

There was a concern that such a near automatic system combining the ACC and the LKAS may adverselyaffect driving.

Will HiDS contribute to a decrease inwakefulness?

Verification of Concerns with HiDS

Will HiDS discourage drivers’ motivation todrive?

Not at all

350

400

450

500

550

Before After Before After

9.4%up HIDSConventional

Res

po

nse

Tim

e [

m s

ec]

Fig.3　Visual Reaction Time

HiDS does not contribute to a decrease inwakefulness.

(Conventional) (Using HiDS)

no decreasedecrease

wakefulness wakefulness

Display Warning

HiDS does not discourage drivers’motivation to drive.

Torque 20%

Torque 80%

＋

Driver

Systemdetection

Assistance

operation

Steering

No Assistance

No detectionSteering mark(Flashing in orange)

monitoring

To utilize the assist function, drivers must continually steer the vehicle.

ConclusionConclusion

HiDS contributes to prevent “careless” or “absent-minded” accidents due to fatigue from long-time driving.

HiDS is a human-centered, new-concept drivingsupport system requiring a driver’s operation as aprerequisite.

New Concept

1. Human driver and the system mustcooperatively drive together

2. Interaction between human and system

HiDS lightens drivers’ workload without reducing theirwakefulness and motivation to drive.