An integrated control of front in-wheel motors and rear electronic limited slip differential for high-speed cornering performance

Abstract

This paper presents an integrated control of in-wheel motor (IWM) and electronic limited slip differential (eLSD) for high-speed cornering performance. The proposed algorithm is designed to improve the handling performance near the limits of handling. The proposed controller consists of a supervisor, upper-level controller, and lower-level controller. First, the supervisor determines a target motion based on the yaw rate reference with a target understeer gradient. The target understeer gradient is devised to improve the lateral stability with in-wheel motor control based on a nonlinear static map. The yaw rate reference is designed based on the target understeer gradient to track the yaw reference with eLSD control. Second, the upper-level controller calculates the desired yaw moments for IWM and eLSD to generate the target motion. Third, the lower-level controller converts the desired yaw moment to the actuator torque commands for IWMs and eLSD. The tire friction limits are estimated based on the tire model and friction circle model to prevent tire saturation by limiting the torque inputs. The proposed algorithm has been investigated via both simulations and vehicle tests. The performance of the integrated control was compared with those of individual control and uncontrolled case in the simulation study. The vehicle tests have been performed using a rear wheel drive vehicle equipped with two front IWMs and eLSD in the rear axle. The vehicle test has been conducted at a racing track to show that the proposed algorithm can improve the lateral stability near the limits of handling.

Trends and Challenges in Electric Vehicle Motor Drivelines - A Review

“…In concept, any architecture may be used, however PM motors with outer ro-tors or axial flux have higher PD and volume usage. There are several variants for reluctance and in wheel induction motors [32]. Table 1 indicates the benefits and drawbacks of various motors.…”

Torque vectoring control of a hybrid drive vehicle to enhance vehicle agility and stability

“…The target variation in the understeer gradient Δ K us is determined using a nonlinear static map that utilizes the steering angle and vehicle speed as input variables. 22,29 It should be noted that the measured lateral acceleration is affected by the gravity component g sin ( ϕ bank + ϕ roll ) of the road bank angle and roll angle. 30 For this reason, in the steady-state control input, the lateral acceleration a y is replaced by the product of the vehicle speed and yaw rate v x γ in order to remove any effect of the gravity component.…”

“…Additionally, the front and rear cornering stiffnesses in Equation (10) are estimated using the recursive least square method with exponential forgetting factor based on the bicycle model as follows 29,31 :…”

“…30 For this reason, in the steady-state control input, the lateral acceleration a y is replaced by the product of the vehicle speed and yaw rate v x g in order to remove any effect of the gravity component. Additionally, the front and rear cornering stiffnesses in Equation ( 10) are estimated using the recursive least square method with exponential forgetting factor based on the bicycle model as follows 29,31 :…”