Advanced Motion Control of Electric Vehicles Based on Robust Lateral Tire Force Control via Active Front Steering

Abstract

This paper presents a new motion control method based on robust lateral tire force control (LTFC) to improve vehicle stability or maneuverability. During cornering, vehicle motion is totally governed by lateral forces acting on tires. Thus, the real-time information on tire forces provides advantages in vehicle motion control. Since the lateral tire force measurements are available by using multisensing hub (MSHub) units which were invented by NSK Ltd., the direct LTFC is realizable via active front steering. In control design, a robust control method, e.g., two degree-of-freedom control (2-DOF) with a disturbance observer, is used for improving the reference tracking performance. Moreover, the stability of the proposed control system is discussed by using small gain theorem. The proposed motion controller is implemented on an experimental in-wheel-motor-driven electric vehicle and its performance and effectiveness are verified by field tests. Finally, practical applications of lateral tire force sensors to vehicle motion control systems are discussed.