Experimental evaluation of vehicle dynamics in longitudinal direction

Abstract

This paper provides a detailed derivation of a full vehicle model, verification of the model and validation of a passenger vehicle model which may be used to simulate the behavior of a vehicle in cornering, throttling and braking maneuvers. The dynamics of a 14 degrees of freedom vehicle model are derived and integrated with an analytical tire dynamics namely Calspan tire model. The model is used to determine vehicle translational motions, as well as roll, pitch, and yaw, based on driver inputs at the steering wheel, accelerator pedal, brake pedal, and bump input from the road. In this study validation of vehicle model is focuses on the longitudinal direction with Proton Iswara Aeroback as the experimental vehicle. Several transient handling performance tests was performed, including sudden acceleration test and sudden braking test at constant speed. Comparisons of the experiment result and model response with sudden braking imposed motion are made. Some of the quantities illustrated include longitudinal slip, longitudinal acceleration and pitch rate. Predictions of the model’s responses agree with the actual measured vehicle’s responses within some specified level of accuracy using qualitative validation. The model will be used to investigate the benefits of a pneumatically actuated active stabilizer bar (PAASB) to improve the vehicle ride quality and handling performance.