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Consideration of Issues

Japan Presentation

Informal document No. GRRF-S08-13

Special GRRF brainstorming session 9 December 2008Agenda item 5

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a. Accident Scenarios in JAPAN

Source: Macro Accident Data 2005

Accidents Involving Large Trucksby Accident Type

Rear-endcollisions55%

Collisions atintersection

corners8%

Collisions whenmaking a right

turn5%

Betweenvehicles or

others18%

Single vehicle2%

Collisions withpedestrians

4%

Collisions whenmaking a left

turn5%

Head-oncollisions

3%

The rear-end collisions of heavy duty truck accounts for more than half of the whole accidents. (Fig.1)

The rate of fatality in rear-end collisions involving heavy duty truck >= 8t are about 12 times higher than that of passenger cars. (Fig.2)

The party responsible

was a large truck.

The party responsible

was a passenger car.

Source: Report on Study and Research for Promotion and Popularization of

ASV Technologies 2004 (Macro Accident Data 2001 to 2003)

Rate of Fatality in Rear-end Collisionsby Type of Vehicle Responsible

0.00%

0.50%

1.00%

1.50%

2.00%

2.50%

3.00%

3.50%

4.00%

4.50%

Expressways

Rates of fatality

0.00%

0.10%

0.20%

0.30%

0.40%

0.50%

0.60%

0.70%

0.80%

0.90%

Rates of fatality

Open roads

Fig.1 Fig.2

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AEBS Basic System (Example)

Sensing System(Radar,Lider,Camera)

CollisionForecast

ComputerBrake Control

Computer

Warning System

BrakeActuator

Speed Sensor

Yaw rate Sensor

Steer Sensor

System

InitiationTTC(Time to Collision)

CollisionUnavoidable Condition

AudibleVisualHaptic e.t.c

Exist Danger of Collision

Should Consider the Following>Emergency Event Preparation>Driver Response Time>Nuisance or False Warning

AEBS Initiation

Collision Warning and Event Preparation

ABS must be equipped

Effort to Earlier Initiation

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b. Sensing Systems

SensorResolution

of Distance

Resolution of

Direction

Ability of Object

Discrimination

Robustness against Weather

Detectionof

Forward Vehicle

Millimeter-wave

RADAR

Scanning-Beam

Good GoodGood

(Vehicle)Good Excellent

Switched-Beam

Good FairGood

(Vehicle)Good Good

LIDAR Good GoodGood

(Vehicle)Fair Good

Camera

Stereo Fair ExcellentExcellent

(Small vehicle and Pedestrian)

Fair Good

Monocular Poor GoodGood

(Small vehicle and Pedestrian)

Fair Fair

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The appearance (1)

Millimeter-wave RADAR(DENSO)

LIDAR(OMRON)

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The appearance (2)

Stereo Camera(SUBARU)

Stereo Camera(LEXUS / TOYOTA)

Monocular Camera(TOYOTA)

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Direction： θ

Distance： D Obstacle

Lateral：Ｌ

Going Lane

①Time to Collision Approx.≦ １ sec （ =D÷Relative Speed ）

②Lateral Distance Vehicle Width≦ ＋ α （ =D×tanθ ）

AND

Algorithm based on Millimeter-wave Radar

Collision Forecast Technology(Example)

(Course Prediction)(Curve Detection)

Position at Every Sampling

ψ

Yew Rate

Steer Angle

Obstacle

Forecast a Collision from the TTC (time to collision) and in the lane or not

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ABS ABS

Driver

AEBS

CollisionUnavoidable ConditionExist Danger of Collision

TTC(Time to Collision)

Hierarchy of Operation (Priority)

High

c. Hierarchy and Decision Control

>AEBS equipped vehicle must have ABS.>In case of unavoidable condition, AEBS has priority over the driver.>In case of expanded area, eliminate obstruction of driver’s avoiding maneuvers.

Must InitiationExpanded Area

AEBS

Driver

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Estimated Case (for example)

AEBS Initiates

Effect to the Driver when the initiation timing of AEBS is not reasonable.Interference with the Driver’s avoiding maneuver =>Nuisance System =>Obstruction of Driver’s avoiding maneuver

When the subject vehicle overtakes the forward vehicle which speed is low by changing the lane, Mitigation Brake works and the subject vehicle can not overtake the forward vehicle.Additionally there may be a dangerous that the the following vehicle collides the subject vehicle

The initiation timing of AEBS should be the case that a collision can not be avoided by the driver or the case that the possibility of the collision is judged high. In other cases, because there is possibility of interference with the driver’s maneuver, the AEBS should not be activated.

(1)Initiation Timing of AEBSBasic Concept

d. Braking and Driver Information

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Driver’s Avoiding Maneuver

1)Braking for Speed Reduction

2)Steer to different direction

1)Brake2)Steer

Relative Velocity

Dis

tanc

e

Limit of Avoidance by BrakingDeceleration＝Maximum constant

There is possibility of interference with the driver’s maneuver.

Interference with the driver’s maneuver could be ignored

Limit of Avoidance by SteeringTTC=constant

MustAEBS Initiation Area

AEBS Initiation Area (’03 First Step)

Japanese Technical Guideline= 0.8sec(Basic System)

11Relative Velocity

Dis

tanc

eThere is interference with the driver’s maneuver.

Interference with the driver’s maneuver could be ignored.

Enhance the Damage Reducing Effect (Second Step Consideration)

TTC= 0.8s

TTC= 1.6s

MustAEBS Initiation Area

Expanded Area

Lower Limit of Usual Avoidance by Steering

Lower Limit of Usual Avoidance by Braking

There is not possibility of interference with the driver’s maneuver at usual condition. > Eliminate Obstruction of Driver’s avoiding maneuver > Eliminate Nuisance or False Braking

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(2)Deceleration and Speed reduction

TTC(Time to Collision)Actual Case Study

CollisionUnavoidable Condition =0.8secExist Danger of Collision

AEBS Initiation

Collision Warning and Event Preparation

Computing TimeFor Collision Forecast

Actuator Response Time

Brake Line Pressure

Vehicle Deceleration

Pad Clearance

Square:Speed Reduction

Target Deceleration

Depend onCharacteristic of Brake Actuator

Peak Deceleration > 3.3m/s2

Japanese Technical Guideline for Target Deceleration

Effort to Earlier Initiation(Enhance Damage Reducing Effect)

Must Initiation

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Driver Information

Audible - Warning sound

Visual-Warning indication in the instrument panel

Haptic

-Warning braking

- Seat belt retraction

- Vibration of steering wheel

- Vibration seat ,Active pedal

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Collision Warning and Event Preparation

TTC(Time to Collision)

Actual Case Study

CollisionExist Danger of Collision

AEBS Initiation

Collision Warning Collision Warning and Event Preparation

Consider Driver Response TimeJapanese Technical Guideline > 0.8sec

Earlier Warning is effective for the Collision Mitigation.However the nuisance or false Warning must be eliminated.

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END

Thank you for your attention.