Eleven professional drivers were used as subjects. Objective measurement showed that in high speed and in double obstacle, sliding seat is superior in attenuating transient vibration and vibration containing transient vibration in horizontal direction and pitching motion compared to fixed seat. Subjective assessment shows that sliding seat gave less overall and low back discomfort. For head and neck area, subjects perceived that seat design had no effect. The results also showed that sliding seat gave lower assessments of pitching and no differences in vertical and rolling assessment.
Objective measurements are well correlated to subjective assessment.
Further studies are needed to formulate a new procedure for summation of multi-degree of freedom which is more appropriate than the procedure which is recommended by ISO 2631 to evaluate vibration environments that have a dominant mode of rotational motion.