Auto seat design and sitting comfort

Auto Seat Design and Sitting Comfort

ERL LLCMarch 1, 2011

Which drive is more comfortable?

No sound Available.

Drive A Drive B

Video Follows

What are Drives A and B?

40 drivers from 25 to 76 years of age Mid-Size Sedan 2 hour highway drive in production seat Measurements in vehicle on highway Michigan State University research

program

Drive A

18 drivers from original 40 in Drive A

Same 2 hour highway drive in seat modified for Mid-Size Sedan

Drive B

Measurements in Drives A & B at Michigan State University.

SubjectiveComfort

Pressure Distribution

Position: 3D Video Measurements Seat Positions

Seat back centerline shape was modified for Drive B.

Foam was added at top of backand removed at bottom of back.

Modified Seat

Production Seat

Changes for Modified Seat came from driver discomfort in

Drive A and ERL model of back posture.

Modified Seat

Production Seat

How did modified seat affect

the driver in Drive B?

11

Driver changed from slumped in Drive A to neutral back posture in

Drive B.

Drive A Production

Seat

Drive B Modified Seat

ERL Patents: US #6,840,125, US#7,047,831, US#7,347,114, US #7,797,138, EU #1019693 & Patents Pending

How do we know?

Measurements in Drives A and B and ERL model to understand the change.

In Drive B, Pelvis rotated 4.6º forward.

Drive A Drive B

Pelvis rotated rearward in the slumped posture.


Slumped Pelvis Position

Pelvis rotates forward when posture changes from Slumped to

Neutral


Slumped Pelvis Position

Neutral Pelvis Position

In Drive B, drivers moved the seat 19mm forward for seat

support.


Slumped Seat Position

Neutral Seat Position

Driver selects fore/aft position for reach

and low pressure on buttocks in seatback.


Slumped Seat Position

Buttocks

In Drive B, the highest pressure point (ID) under buttocks moved rearward.

Production (ID-Pt) Modified (ID-Pt)

ID is the highest pressure point under the

pelvis.


Slumped ID Position

ID moves rearward on seat when posture changes from Slumped to

Neutral.


Slumped ID Position

Neutral ID Position

Eye height is a function of torso posture.


Slumped Line of Sight

In Drive B, the driver’s eye moved upwards 11mm and rearwards 17mm.



Neutral Line of Sight

In Drive B, drivers raised the steering wheel 3.6º.


Drive ADrive B

Drive A Slumped Posture

Drive B Neutral Posture

Drivers position steering wheel fortheir preferred arm and leg joint

angles.


ERL, LLC

Eye and shoulder rise with change from slumped to erect

postures.

ErectNeutralSlumped


Eye

Shoulder

Every time drivers adjusted the seat,

position was recorded by computer.

15

25

35

45

55

65

75

85

95

0:00 0:28 0:57 1:26 1:55 2:24

Dis

tan

ce (

mm

)

Time

Seat Adjustments

Fore/Aft

Seat Height

Rear

Front

The longest time in one position is the Modal Period of seat position.

15

25

35

45

55

65

75

85

95

0:00 0:28 0:57 1:26 1:55 2:24

Dis

tan

ce (

mm

)

Time

Modal Period

Modal period increased from 45 in Drive A to 75 minutes in Drive

B.

15

25

35

45

55

65

75

85

95

0:00 0:28 0:57 1:26 1:55 2:24

Dis

tan

ce (

mm

)

Time

Modal Period

Small and large drivers use back posture to meet different needs.

30

Small women prefer Neutral & Erect back postures.

Erect

Neutral

Slumped

5th%tile


Line of Sight

Headliner

31

Change in posture raises eye height for better downward vision.

Erect

Neutral

Slumped

5th%tile


Headliner

Erect Line of Sight


Slumped

Erect

32

Preferred back posture is neutral which uses least

muscle activity.

Erect

Neutral

Slumped

50th

%tile

All spinal joints are in the middle of their range of motion.


33

Headliner too close for neutral posture in large

male.

Erect

Neutral

Slumped

95th

%tileHeadliner


34

Headliner often forces large male into slumped posture.

Erect

Neutral

Slumped

95th

%tile


Headliner

35

Slumped posture needsadditional rearward

travel.

Erect

Neutral

Slumped

95th

%tile


Headliner

Seat moves

rearward.

Why do the seat and package promote a slumped posture?

Head restraint position pushes head forward into slumped posture

Can be modified for comfort and Federal

regulations

Low seat back pushes buttocks forward into slumped posture.

Can be modified for comfort and Federal

regulations

Can be comfortable with different

design.

In new vehicles, seat still pushessmall woman into slumped posture.

Seat design must pass the H-point test and head restraint regulation.

Comfort is a development goal at supplier for seats that meet H-point and safety requirements!

Oscar back shape and body size define test requirements for interior.

Oscar: 50th% Torso 95th% Legs

Oscar back shape does not represent a slumped posture.

Oscar: 50th% Torso 95th% LegsERL: 50th% Torso 50th% Legs

Slumped posture in 50th %tile male

Oscar back shape does not represent a neutral posture.


Neutral posture in 50th %tile male

Oscar’s highest pressure point (ID) is posterior of the Medium Male


Neutral ID Position

Oscar’s ID Position

46

Seat designed first for “Oscar’s” unique back

posture.

“Oscar”

47

Seat designed to pass H-point test.

SAE Practice: “Slide the H-point machine rearward … until the seat pan contacts the seatback.”

Unique Back Posture

48

Seat designed to pass H-point and Head Restraint

Tests.

SAE Standard: “Slide the H-point machine rearward … until the seat pan contacts the seatback.”

Unique Back Posture

DOT Regulation requires head restraint within 55 mm of Oscar’s head.

Seat modified for Comfort at Supplier using drive iterations.

The production seat in Drive A did not past the H-point test.

H-point of Oscar

Test requirement: H-point within ½” of

SgRP

Seating Reference Point (SgRP)

The ERL modified seat in Drive B passed the H-point test.

H-point of Oscar

Test requirement: H-point within ½” of

SgRP

Seating Reference Point (SgRP)

Do all drivers find cars that fit?

“She said that when they went to look at new cars, she (she is about 5 ft 2 inch) never found a car that really fit her, but she accepted that, and chose cars by reliability, mileage, and color because she had no other choices!

How does seat design meet all requirements including comfort?

Driver:◦ Seat◦ Pedal◦ Steering Wheel◦ Vision

The passenger needs room for feet, knees and head!

Driver needs to feel that the interior parts totally fit.


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Optimize seating at beginning of design, not at the end of

development.

Erect

Neutral

Slumped

5th 95th

J826

HRMD

50th

Vision

ComfortSpace


ERL’s tools in this presentation used to explain the difference between Drive A and Drive B can be used for seat design to meet H-point test, safety test, and comfort tests at the beginning of vehicle development.

Conclusion

Thanks for your time and interest.

For more information, contact:

ERL [email protected]

mailto:[email protected]

Auto seat design and sitting comfort

Automotive

Transcript of Auto seat design and sitting comfort