Download - Design review of a car seat for ergonomics
DESIGN PARAMETERS OF
SEAT
FIT PARAMETER
FEEL PARAMETER
SUPPORT PARAMETER
FIT PARAMETERS Cushion width
Cushion length
Backrest Width
Backrest Height
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
SCHEMATIC REPRESENTATION
OF FIT PARAMETER
CUSHION LENGTH
FEEL PARAMETERS Pressure
Shear stress
Temperature
Humidity
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.
SUPPORT PARAMETERS Lumbar Support
Body Segment Angles and Seat Adjustments
Knee Angle
Trunk/Thigh Angle
Lumbar SupportMethodologies :
Anthropometry
Electromyography
Reynolds (1993) model of linkage representations of the human body:
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.
NEW CAR-SEAT CONCEPT BASED ON THE HUMAN BODY CONTOUR DEVELOPED AT BMW (FRANZ ET AL.)
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.
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.
THE 16 EMOCARD PLACED ON RUSSELL’S
CIRCUMPLEX OF EMOTIONS.
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
OVERVIEW OF MENTIONED
SEAT CONTOURS
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%).
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.
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