Error analysis for an active geometry control suspension system

In order to improve the safety and comfort of passenger cars, many techniques have been proposed. Among them, the utilization of parallel mechanisms in rear suspensions has a great potential to increase the performance and stability of vehicles. In this paper, the error analysis of camber and rear steering angles, due to the use of a 3-DOF parallel mechanism as a vehicle suspension, is developed. Basically, two error sources are taken into consideration here, namely, manufacturing tolerances and actuators inaccuracies. In order to evaluate camber and rear steering angles, a kinematic model is derived. Then, a prediction of errors associated with those angles is conducted by two distinct methods. One method performs an error mapping inside the mechanism workspace, while the other one employs a parametric optimization. Finally, an impact of predicted errors on a vehicle dynamics is evaluated by performing three manoeuvres: steady-state cornering, fishhook and double lane change. The approach presented here and results obtained can contribute to other new researches about vehicle control systems.