In India, small car segment is having maximum sale, which
includes cars like Maruti 800, SUZUKI Swift, Maruti Alto, Tata
Indica, etc. Driver seat is one of the main aspects to be
considered while defining comfort in a moving vehicle. The current
analysis concentrates on driver seat because driver comfort is of
main concern since it is the most occupied seat in any vehicle and
the occupancy is for longer duration. In addition to sitting, the
driver's job is to manipulate different controls and
concentrate parallely on many aspects. The research work aims at
studying the vertical vibrations transferred to the human body via
seat.
The work is an attempt towards studying dynamic characteristics
of driver seat for comfort through objective evaluation. For
objective evaluation, two tests were conducted; Seat Effective
Amplitude Transmissibility (SEAT) test and Ride Comfort Index test
under two different conditions, i.e., car level and seat level
testing on Car "A" and Car "B." Both tests were
carried out under controlled conditions.
Car level test was carried out on 4-Poster simulator, which can
simulate exact road conditions in vertical direction whereas seat
level testing is done on electro-dynamic shaker, which simulates
sinusoidal signals. Results of experimentations, i.e.,
accelerations at seat base and seat mount were compared with
reference standard ISO 2631-1(1997) which indicated average Root
Mean Square (RMS) of Car "A" and Car "B" is
0.007 and 0.008 Km/s₂ respectively. Hence according to ISO
2631-1(1997), both cars fall into "fairly uncomfortable
zone". SEAT Test revealed transmissibility in two different
positions (front most and rearmost position). In front most
position, transmissibility is 65.66% and 204% for Car "B"
and Car "A" respectively, whereas transmissibility is
63.56% and 145% for Car "B" and Car "A" in
rearmost position of seat.