Yaw-rate control for electric vehicle with active front/rear steering and driving/braking force distribution of rear wheels

Abstract

Direct yaw-moment control (DYC) is an effective method for achieving stable vehicle motion. In the DYC of vehicles having in-wheel motors (IWMs) and active front and rear steering systems, some of the control inputs are generally redundant. This means that input variables can not be decided uniquely to control each longitudinal, lateral, and yawing motion. The equalization of workload for each wheel on the basis of longitudinal and lateral force distribution enhances the cornering performance of vehicles. Therefore, we have proposed a method for obtaining longitudinaland latitudinal-force distributions on the basis of the least squares solution of the equations for longitudinal, lateral, and yawing motion. Further, we have proposed a lateral-force control method with tire lateral force sensors and active front/rear steering and a DYC method for reducing the tracking error in this controller. In this paper, we show that the equalization of the workload for each wheel and quick yaw-rate response are achieved by adopting these proposed methods. Simulations and experiments are carried out to confirm the effectiveness of the proposed methods. © 2011 The Institute of Electrical Engineers of Japan.