Ergonomic study on car seat design to improve the comfort of Malaysian drivers

Abstract

Apart from the aesthetic value of automobile design, being safe and providing comfort to the occupants are among the selling points of car manufacturers. However, poor pressure distribution with constrained posture in terms of long driving hours and cramping with limited space upon the vehicle packaging factor would lead to musculoskeletal disorders. The present work was aimed at changing the mainstream padding material for car seats to the concern on having greater pressure distribution as well considering Malaysian anthropometry measurement to reduce musculoskeletal disorders. First, the adequacy of driver seats from commonly used vehicles in Malaysia was measured and the dimensions were compared with the Malaysian anthropometric database. The result showed that the ergonomic aspects of the driver seats designed are in compliance with the standard based on the database. This finding was triangulated with previous studies that found that the dimensions for most commonly used cars in Malaysia do follow the Malaysian anthropometry data. Secondly, to scrutinize the finding, the common types of driving posture of Malaysian drivers from the previous studies were extracted and assessed by an ergonomic tool. The posture scores were analysed according to the Rapid Upper Limb Assessment (RULA). These posture scores indicated that they were in the medium risk range. Thus, the driver seat could be improved to make it more ergonomic and comfortable. Lastly, the ergonomic improvement and driving comfort were established through the modification of seat cushion foam. The designed seat was analysed through pressure distribution and subjective assessment over 30 respondents who sat on the modified car seat for at least 60 minutes. The differences in peak pressures recorded between the original and modified seats showed an average of 2 kPa pressure reduction for the 95th percentile, 4 kPa for the 5th percentile, and 3 kPa for the 50th percentile. The improvement in the comfort level was also proven when 23 of the 30 respondents commented on the comfortness over sitting on the modified seat for 60 minutes. It is ascertained that the new seat foam with the designed pressure distribution could be a niche for providing better ergonomic posture and increasing drivers’ comfortness.