Comparisons of Whole Body Vibration, Muscle Activity and Non-driving Task Performance between Different Seat Suspensions in an Autonomous Passenger Car Application

Abstract

This study compared whole body vibration (WBV), muscle activity and non-driving task performance between different seat suspension settings in a simulated autonomous passenger car environment. To simulate autonomous vehicle environment, field-measured vibration profiles were recreated on a large-scale 6-degree-of-freedom motion platform. In a repeated-measures laboratory experiment, we measured whole body vibration, muscle activity (neck, shoulder and low back), participants non-driving task performance while participants performed non-driving tasks (pointing task with a laptop trackpad, keyboard typing, web-browsing, and reading) on three different suspension seats mounted on the motion platform: vertical (z-axis) electromagnetic active suspension, multi-axial (lateral (y-axis) and vertical (z-axis)) electromagnetic active suspension, and no suspension (industry standard suspension-less seat for passenger cars). The average weighted vibration [A(8)] and vibration dose value [VDV(8)] showed that the seat measured vibration on both the vertical [A(8) = 0.29 m/s 2 and VDV(8) = 10.70 m/s 1.75 ] and multiaxial suspension seats [A(8) = 0.29 m/s 2 and VDV(8) = 10.22m/s 1.75 ] were lower than nosuspension seat vibration [A(8) = 0.36 m/s 2 and VDV(8) = 12.84 m/s 1.75 ]. Despite the significant differences in WBV between the different suspensions there were no significant differences across three different suspension seats in typing performance (typing speed and accuracy: p's > 0.83), pointing task performance (movement time and accuracy: p's > 0.87), web-browsing (number of questions and webpages read: p = 0.42), and reading (number of words read: p = 0.30). The muscle activity in low back (erector spinae) and shoulder (trapezius) muscles also did not show any significant differences (p's > 0.22). These laboratory study findings indicated that despite the significant reduction in WBV, neither vertical nor multi-axial active suspension seats improve non-driving task performance as compared to the no-suspension seat.