City bus seat vibration analysis using 6-axis accelerometer and gyroscope sensors

This paper analyses different modes and cycles of seat vibration in city buses by analysing acceleration peak magnitudes and their trends and fluctuations in the time domain. The purpose is to find peak vibration modes that exist in the driving patterns of city buses. Analysing peaks in a time series is essential for many applications specifically in vibration analysis because they represent significant events. Using a 6-axis inertial measurement unit device which has accelerometer and gyroscope sensors data were collected from a number of city buses operating. By applying algorithmic filters the g-force peaks present in different acceleration modes were analysed. The particularity of city bus seat vibration and g-force acceleration levels due to effective acceleration in 3-axes are presented and discussed, namely: longitudinal (forward motion), lateral (side-to-side) and vertical (bounce mode) accelerations. It was found that the bus seat root mean square acceleration magnitude of approximately 0.33 g occurred from the major acceleration cycles during bus running. In longitudinal, lateral and vertical directions, 20% of peak acceleration cycles were above 0.20 g, 0.18 g and 0.27 g respectively. Jerk may be a better indicator of passenger discomfort. The results from this study can provide future reference to research directions into understanding city bus seat vibration levels in longitudinal, lateral and vertical directions and also initiatives to mitigate excess bus seat vibration for the riders.