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.
