Improving the braking performance of a vehicle with ABS and a semi-active suspension system on a rough road

Rapid advances have been made in the field of vehicle dynamics in terms of improving the ride, handling and safety using actuators and control systems. Optimising a vehicle’s ride comfort or handling has led to the development of semi-active suspension systems. Anti-lock braking systems (ABS) have resulted in significant improvements in vehicle braking whilst maintaining directional control over the vehicle. These advances have improved vehicle and occupant safety in general, but there are often some trade-offs. For example, the stopping distance of a vehicle fitted with ABS on an undulating road is significantly increased compared to braking without ABS. This has severe implications, especially in the off-road vehicle industry. The effects of spring and damper characteristics on the braking performance of a sports-utility-vehicle (SUV) on hard rough terrain are investigated. The approach is simulation based, using an experimentally validated full vehicle model of the SUV, built in Adams in co-simulation with MATLAB and Simulink. The simulations were performed on measured road profiles of a Belgian paving and parallel corrugations (or a washboard road). The results indicate that the suspension system has a significant impact on the braking performance, resulting in differences in stopping distances of up to 9 m.