COORDINATED ACTIVE REAR STEERING AND VARIABLE TORQUE DISTRIBUTION CONTROL FOR VEHICLE STABILITY ENHANCEMENT

摘要

This paper investigates the coordination of Active Rear Steering (ARS) and Variable Torque Distribution (VTD) control to improve the overall vehicle stability and controllability, especially under extreme driving situations. Both ARS and VTD are able to influence the vehicle lateral dynamics to some extent within different effective regimes. The steerability and stability controller, ARS, is mainly designed to tune the vehicle handling at low to mid-range lateral acceleration level; while the stability controller, VTD, uses the differential driving torques between left and right driving wheels to produce a relatively large stabilising yaw moment when the vehicle states (sideslip angle and sideslip angle velocity) exceed the predefined stable region. The effect of the simultaneous use of ARS and VTD on the vehicle stability is studied through an open loop limit handling simulation test based on a eight degrees of freedom vehicle model. In addition, the adaptiveness of the proposed control system to the road surface friction variation is investigated as well. Computer simulation results confirm both the overall improvements in vehicle stability and the effectiveness of the proposed combined control system.