This document discusses parameters for designing car seats, including fit, feel, and support parameters. Fit parameters include cushion width, length, and backrest width and height. Feel parameters involve pressure, shear stress, temperature and humidity. Support parameters focus on lumbar support and body segment angles during seating. A case study evaluated three different car seat designs - one with steep wings for sports cars, one less contoured for luxury cars, and a new BMW design based on human body contour. The study objectively measured seat dimensions and subjectively assessed participant emotions toward the seats using an Emocard method. Results found the BMW design elicited the most positive emotions overall.

2. DESIGN PARAMETERS OF
SEAT
 FIT PARAMETER
 FEEL PARAMETER
 SUPPORT PARAMETER

3. FIT PARAMETERS
 Cushion width
 Cushion length
 Backrest Width
 Backrest Height

4. RECOMMENDED FIT PARAMETERS
Parameter Minimum
(mm)
Maximum (mm)
Cushion width
• actual width at H point 432
• clearance at H point 500
• width at front of cushion 500
Cushion length
• forward of H point on
thigh line
305
Backrest width
• at waist (220 mm above H
point)
360
• at chest (318 mm above H
point
456
Backrest height 410 550

5. SCHEMATIC REPRESENTATION
OF FIT PARAMETER

6. CUSHION LENGTH

7. FEEL PARAMETERS
 Pressure
 Shear stress
 Temperature
 Humidity

8. Pressure
 Body tissues can readily tolerate up to 240 psi
(12400 mm Hg).
Temperature and humidity:
 Heat flux :The total heat flux through the seat,
including heat transfer due to evaporation, should be
about 75 W/m2.
 Material :Perforated cover materials are desirable
because of reduced resistance to water vapour
diffusion.

9. SUPPORT PARAMETERS
 Lumbar Support
 Body Segment Angles and Seat Adjustments
Knee Angle
Trunk/Thigh Angle

10. Lumbar Support
Methodologies :
Anthropometry
Electromyography

11. Reynolds (1993) model of linkage representations
of the human body:

12. CASE STUDY OF CAR-SEAT
DESIGN
Three seats were chosen based on their difference in
design and on the car model :
 one seat with steep wings used in sportive cars
 one seat that is less contoured used in luxurious cars
 and a new seat concept based on the human body
contour developed at BMW.

13. NEW CAR-SEAT CONCEPT BASED ON THE HUMAN
BODY CONTOUR DEVELOPED AT BMW (FRANZ ET AL.)

14. METHODOLOGY
 OBJECTIVE RESEARCH:
To define the shape and contour of all three seats, the following aspects
where measured:
 WIDTH OF SEAT AND BACKREST
 STEEPNESS OF BACK- AND SEAT WINGS
 CONTOUR OF BACKREST
 The hardness of the seat cushion, based on the thickness of the foam
material and hardness in kPa.

15. SUBJECTIVE RESEARCH
 PARTICIPANTS: 21 participants. Their mean height was 1.78 (1.63e1.92)
m and their mean weight was 76 (48e107) kg.
 SEATS: All have the same backrest angle (25°) .
 SET-UP: All seats were covered with a thin blanket. Emocard method
was applied. All seats were tested for approximately 5 min.

16. THE 16 EMOCARD PLACED ON RUSSELL’S
CIRCUMPLEX OF EMOTIONS.

17. DIMENSIONS OF SEAT UNDER
OBSERVATION
Seat width
(cm)
Seat wing
(°)
Contour 1 50-31 51
Contour 2 48-29 35
Contour 3 52-52 No wings
Backrest
width
(cm)
Backrest
wing
(°)
Contour 1 49-31 60
Contour 2 51-27 47
Contour 3 50-50 No wings

18. OVERVIEW OF MENTIONED
SEAT CONTOURS

19. RESULTS
 The Emocard chosen by 71% of the participants shows
a pleasant emotion, but medium level of arousal.
 The most important findings are that hard seats with
rather high side supports are rated sporty, seats that
are softer are rated more luxurious.
 The intensity of the color indicates the level of arousal
(the darkest shade is the highest arousal). The most
positive overall emotions are elicited by seat contour 1
(86%), followed by contour 2 (76%) and contour 3
(52%).

20. REFERENCES
 Irene Kamp
Faculty of Industrial Design Engineering, Delft University of
Technology, Landbergstraat 15, 2628 CE Delft, The
Netherlands.
The influence of car-seat design on its character experience
 Matthew P. Reed, Lawrence W. Schneider,Leda L. Ricci
University of Michigan Transportation Research Institute
Survey of auto seat design recommendations for improved
comfort
 Broman, H., Pope, M. H., Benda, M., Svensson, M.,
Ottosson, C., and Hansson, T. (1991, January).
The impact response of the seated subject. Journal of
Orthopaedic Research.

21. THANK YOU