Handling Performance Improvement via Steering Reactive Torque Design Based on Integrated Driver-Vehicle Model

In some specific driving conditions, the steering behavior of the driver is significantly influenced by the reactive torque of the steering system. According to the vehicle dynamics, the steering angle along with the longitudinal velocity determines the vehicle states as well as the driving feeling. Thus, the steering reactive torque shows a remarkable influence on the evaluation of the lateral stability in high-speed condition. Given that the steady state gain increases with the velocity, this effect is especially significant in the high speed condition. As a result, the steering reactive torque must be designed to match the vehicle speed properly. However, except for simple experiential method, no normative design procedure of the reactive torque is proposed at present. In this paper, the influence of the steering reactive torque on the driver’s steering behavior is studied on the basis of the integrated neuromuscular system (NMS) vehicle model, which shows that a larger reactive torque could effectively restrain the unnecessary rapid steering operations and thus improve the handling performance of the vehicle. Key states of the vehicle dynamics is selected as the parameterized index of the physiological perception of the lateral stability. A novel design approach of the steering reactive torque is then proposed on the basis of the correlation of the reactive torque and the vehicle states. By introducing a new design principle — maintaining the physiological-perception-related dynamics states, the evaluation of the lateral stability can remain favorable despite the increasing speed. Effectiveness of the proposed design procedure is validated by a driving simulator and promising results have been obtained.