Investigation of a steering defect and its compensation using a steering-torque control strategy in an extreme driving situation

摘要

Road feel is mostly represented by the steering torque or the steering-torque gradient of the lateral acceleration, and it is used by the driver to adjust the vehicle states and to control the vehicle. A steering defect indicated by a decreasing steering torque with increasing lateral acceleration makes the driver lose road feel and may result in a wrong operation and even a traffic accident. The case where the driver loses road feel can be regarded as an extreme driving situation. This paper investigates the steering defect and proposes a steering-torque-based control strategy to improve road feel in a vehicle in an extreme driving situation. The steering torque and the steering-torque gradient extended to the non-linear region of the vehicle are analysed and simulated, and both the simulation results and the experimental results indicate that the steering defect exists when the lateral acceleration is relatively high. Thus, a steering-torque control strategy is proposed on the basis of the torque gradient to improve road feel in an extreme situation. This steering-torque control strategy helps to maintain road feel by employing an optimized steering-torque threshold. The simulation results of the vehicle with steering-torque control show improved road feel in comparison with that without steering-torque control.