A FCW, CIB and DBS benefit estimation method developed in ACAT program

Hirofumi Aoki, Masami Aga, Yoshiki Miichi, Yoshiaki Matsuo, and Shin

TanakaToyota Motor Corporation

Developing Systems to Reduce/Mitigate Rear-end Collisions

Toyota

Honda

Subaru

Mercedes

Volvo

Control Sequence

FCW, DBS and CIB specification

System benefit

The objective in ACAT

Ordinary

DrivingCollisio

n

DBS (Brake Assist)FCW

CIB (Automated braking)

Time

Speed

Drivers reaction to BenefitOrdinar

y Driving

Collision

Time

Speed

FCW + DBS

CIB

DBS (Brake Assist)FCW

CIB (Automated braking)

Drivers reaction to Benefit

So…

Each benefit significantly depends on

“how drivers react before collisions”.

Ordinary

Driving

Time

Speed

Collision

FCW + DBS

CIB

DBS (Brake Assist)FCW

CIB (Automated braking)

Driver behavior investigation using the Driving Simulator

Driving Simulator Test Example

Driver Reaction Before Collisions

Maximumdeceleration

20 - 30s40 - 50s60s -

Period from warning to braking onset

0

2

4

6

8

10

0.0 1.0 2.0

[m/s2]

[s]

(31 persons in total)

Rear-end Reconstruction Concept

How are rear-end collisions

happening?

Traffic accidents are happening incidentally

Rear-end Collision ModelingRear-end collisions are happening by a combination of

Braki

ng

pat

tern

s

* Various braking patterns

Coasting

Various brake trigger timings

Brake trigger timing

* Various response delays

Braking

How was the hypothesis verified

EDR Data Analysis

- 60

- 40

- 20

0

Sp

eed

red

ucti

on

(m

ph

)

3m/s 24m/s 25m/s 2

0

10

20

30

Nu

mb

er

of

cases

None-1s

(Total 70 cases)

20

28

11

41

6

-2s -3s -4s -5s

Braking onset before a crash

None-1s -2s -3s -4s -5s

Braking onset before a crash

Source : NHTSA EDR database

CDR system connected to a crashed vehicle

ftp://ftp.nhtsa.dot.gov/NASS/EDR_Reports/

Comparison between EDR

10

20

30

40

[%]

Fre

qu

en

cy

50

Sp

eed

red

ucti

on

[m

ph

]

0

-30

-20

-10

-40

-50None

-1s

-2s

-3s

-4s

-5s

None-

1s-

2s-

3s-

4s-

5s

and simulation result

0

Simulation result

Braking onset before a crash

Braking onset before a crash

EDR

Simulation result shows similarity to EDR

Rear-end Collision SimulationWithout a System

B

D

A

C

E

CoastingBrakin

g

Braki

ng

pat

tern

s

System benefit can be estimated by comparing P v.s. A, Q v.s. B, R v.s. C and so on.

With a System

Warning

Q

S

P

R

T

DBS CIB Danger is noticed later thanwarning onset

Braking onset

will besooner

Danger is noticed prior towarning onset

+FCW,DBS & CIB

FCW onset

DBS onset

CIB onset

= 1.7 sec= 0.8 sec= 0.45 sec

SV = 20m/s

*e.g., sleepy or fell asleep

Expected to push brake pedal

(%)

Speed reduction

Crash avoidance ratio

0

5

10

15(mph)

FCW FCW +DBS

FCW +DBS +CIB

CIB

Not expected to push brake pedal*

3.2mph

6.3mph8.1mph

4.5mph

0

5

10

15

0.0% 0.0% 1.0% 0.0%

*Under the Japanese MLIT guideline in 2003

Simulation 1

FCW FCW +DBS

FCW +DBS +CIB

CIB

5.7 mph

12.3 mph15.4 mph

9.1 mph

0.0%7.9 %

13.5 %

0.0 %

Simulation 2

FCW onset

DBS onset

CIB onset

= 2.0 sec= 1.1 sec= 0.75 sec

SV = 20m/s

(%)

Speed reduction

Crash avoidance ratio

0

5

10

15(mph)

FCW FCW +DBS

FCW +DBS +CIB

CIB

0

5

10

15

FCW FCW +DBS

FCW +DBS +CIB

CIB

Expected to push brake pedal

Not expected to push brake pedal

Conclusions

An estimation of the benefit of FCW, CIB and DBS was developed.

1. Driver response before collisions was measured in the driving simulator. It was shown that response varied widely from person to person.

2. Rear-end collisions were reconstructed. The result was validated with the EDR data analysis.

3. Estimation method demonstrated the benefit difference by each specification.

Current Study; LDW benefit estimation

End