Skid Control of Small Electric Vehicles : Direct Yaw Moment Control using Tire Steer Angle

Due to the space limitation of the driving tire, some small electric vehicles with two in -wheel motors employ a hydraulic-mechanical brake system (HMBS) as a braking system. Although the mechanical braking system is compact, the rigidness and the response performance of the mechanical braking system is lower than a hydraulic braking system. On the other hand, a small electric vehicle only employs a seat belt as safety equipment, and there is no antilock braking system (ABS), which is a basic skid control system. Furthermore, the inertia moment of the rear tire is larger than the front one because an in -wheel motor was attached to the rear tire. During braking and disturbance, due to the disadvantage of the mechanical braking system and the large inertia moment of the rear tire, the vehicle easily loses its stability, increasing the possibility of an accident. In this paper, to increase the stability and the safety of the small electric vehicle with two in -wheel motors, we propose a novel method based on the yaw moment of the vehicle. This method is known as a direct yaw moment control (DYC) using tire steer angle. The state feedback control method and the feedback gain matrix for tire steer angle have been used in our model. The input of this system is the tire steering angle while the output is the yaw angular velocity and the side slip angle of the vehicle. The simulation result shows that during braking and disturbance, DYC can improve the vehicle motion for the driver desired direction and increase the stability of the vehicle.