Evaluation of Road Roughness and Vehicle Speed Effects on Vibration Comfort of School Bus Driver Seats following the ISO 2631-1 Standard and Occupational Health and Safety Legislation

Abstract

Human perception in terms of vehicle comfort problems is a significant issue for automotive manufacturers and academic researchers as evident from scientific papers available in the literature. In this study, the maximum vehicle speed is predicted for comfortable driving of school bus drivers at certain working conditions. First, a full-vehicle school bus model, which consists of a seat, vehicle body, wheels and suspension systems, is developed to evaluate vehicle seat comfort in accordance with International Organization for Standardization (ISO) 2631-1 and Occupational Health and Safety (OHS) legislation. Second, collected experimentally power spectrum densities of road roughness are converted to amplitude form in order to be an input to the developed full-vehicle model. Third, the frequency weighting factor, which is determined by International Organization for Standardization 2631-1, is applied to the calculated RMS acceleration of the seat. Finally, frequency-weighted RMS accelerations of the seat for various conditions of road roughness and vehicle speeds are obtained, and it is used to evaluate the bus driver seat comfort in accordance with ISO 2631-1. In addition, RMS accelerations of the bus driver seat are used to evaluate vehicle seat comfort in accordance with OHS legislation. It is concluded that the effects of vehicle speed and road roughness on comfortable driving are observed and maximum vehicle speed for comfortable driving decreases as the power spectrum density of road roughness increases. According to the results, measures to be taken in accordance with the OHS legislation are suggested.