Trajectory tracking based on independently controlled variable-geometry suspension for in-wheel electric vehicles

The paper presents a new variable-geometry suspension system which is applied in-wheel electric vehicles. It is able to realize the steering of the vehicle by independent wheel camber angles and wheel steering and create differential yaw moment by harmonizing the longitudinal forces. In order to perform the trajectory tracking of the vehicle the control signals are the virtual signals, such as differential yaw moment and steering by wheel camber angles. In the suspension system two physical active torques are realized on either side of the front axle and longitudinal forces are realized by in-wheel motors. The control design of the variable-geometry suspension system is based on a hierarchical structure. The purpose of the high-level controller is to calculate the virtual control inputs based on the performance specifications for the road trajectory. The purpose of the low-level controller is to realize the physical active torque of the wheels and track the required differential yaw moment.