computer aided ergonomics case study: vehicle brake system · computer aided ergonomics case study:...

Research & Advanced Engineering

Computer Aided Ergonomics

Case Study: Vehicle Brake System

Dipl.-Math. (FH) Jessica Rausch & Dr.-Ing. Karl Siebertz

Ford Forschungszentrum Aachen



Motivation for Biomechanics

• Short development cycles require early ergonomic assessment.

• Better ergonomic performance without expensive features

requires advanced ergonomic analysis tools.

• Many ergonomic issues are related to muscle activation.

• Customer clinics are not suitable for parameter screening and design

optimisation.

Motivation

need for test methods and

Computer Aided Ergonomics using

a biomechanical model of the human body


Motivation for BiomechanicsRole of the AnyBody Car Driver Model

input tool output benefit

muscle loads objective

+ comfort index data

package data

force-characteristics distribution of comfort index reduced

AnyBody for driver population testing effort

CDM

movement analysis parameter variation system

for baseline design + sensitivity analysis integration

(3-4 test subjects)

generic transfer functions design

for similar cases guidelines


Motivation for BiomechanicsWorking Areas: Computer Aided Ergonomics

computer model

of car + driver

motion prediction performance criteria

variation of the

human body

Computer Aided Ergonomics

experimental

motion analysis

motion tracking interface

CAD Interface

motion data base

interpolation or simulation

of motion control

data

condensation

fatigue

model

geometric

scaling

strength

scaling

3rd age

force

data base

target values


Validation Study: Braking

• Ford test vehicle, tunable force

characteristic for brake pedal.

Partially obstructed view.

• Motion analysis:

Qualisys for the upper body and the left leg;

Goniometers at the right leg;

Potentiometer for right heel

• External Loads:

contact switch to identify heel position;

pressure mapping to estimate seat support;

force transducer at the brake pedal

• EMG measurements of right leg muscles



-10 0 10 20 30 40 500

50

100

150

pedal travel in mm

ped

al fo

rce in

N

activate

release


0 1 2 3 4 5 6 70

0.2

0.4

0.6

0.8

1

Tibialis Anterior

time in s

no

rma

lize

d v

alu

e

Test: EMG envelopeCAE: muscle activity

0 1 2 3 4 5 6 70

0.2

0.4

0.6

0.8

1

Soleus

time in s

no

rma

lize

d v

alu

e


0 1 2 3 4 5 6 70

0.2

0.4

0.6

0.8

1

Vastus Lateralis

time in s

no

rma

lize

d v

alu

e


0 1 2 3 4 5 6 70

0.2

0.4

0.6

0.8

1

Rectus Femoris

time in s

no

rma

lize

d v

alu

e




CAE Parameter Variation: Seating Position

x

y

z

AnyBody Car Driver Model,

Ford Mondeo package,

artificial brake characteristic,

variation of the H-point,

50% female human model,

DoE with full factorial design,

3rd order polynomial model

(without cubic effect of y-pos,

due to array construction)

Factor min max levels

x-pos -0,16 -0,08 5

y-pos -0,01 0,01 3

z-pos -0,025 0,05 4

[m], 50% female pos. , compared to 95% male H-point


y_pos=0,0

x_posz_pos

max_Act0,40,420,440,460,480,5

-0,16-0,14-0,12-0,1-0,08

-250

2550

(X 0,001)

0,4

0,45

0,5


Main Effects Plot for max_Act

ma

x_

Act

x_pos-0.16 -0.08

y_pos-0.01 0.01

z_pos-0.025 0.05

0,4

0,42

0,44

0,46

0,48

0,5

Interaction Plot for max_Act

ma

x_

Act

AB-0.16 -0.08

-

-

+ +

AC-0.16 -0.08

- -

++

BC-0.01 0.01

-

-

++

0,4

0,42

0,44

0,46

0,48

0,5


x-pos -0,16 -0,08 5

y-pos -0,01 0,01 3

z-pos -0,025 0,05 4


R

%96 2

=adjRmodel polynomial order 3rd


y_pos=0,0

x_pos

z_pos

mean_A

ct

-0,16-0,14-0,12

-0,1-0,08

-2502550

(X 0,001)

26

28

30

32

34

36

(X 0,001)

Main Effects Plot for mean_Act

me

an_A

ct

x_pos-0.16 -0.08

y_pos-0.01 0.01

z_pos-0.025 0.05

26

27

28

29

30

31

32(X 0,001) Interaction Plot for mean_Act

me

an

_A

ct

AB-0.16 -0.08

-

-

+

+

AC-0.16 -0.08

-

-

+

+

BC-0.01 0.01

-

-

+ +

26

28

30

32

34

36(X 0,001)


x-pos -0,16 -0,08 5

y-pos -0,01 0,01 3

z-pos -0,025 0,05 4



%6,98 2

=adjRmodel polynomial order 3rd


Conclusions

Computer Aided Ergonomics is a valuable tool to improve the vehicle design.

Many working areas need to be addressed simultaneously.

Several of them are related to the human body as such,

others will streamline the workflow and speed up the turn around time.

The validation results of the AnyBody Car Driver Model are promising.

Meta-modelling helps to communicate results to the product development.

DoE seems to work well in this context.

computer aided ergonomics case study: vehicle brake system · computer aided ergonomics case study:...

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