Handling Improvement for Distributed Drive Electric Vehicle Based on Motion Tracking Control 2018-01-0564
The integrated control system which combines the differential drive assisted steering (DDAS) and the direct yaw moment control (DYC) for the distributed drive electric vehicle (DDEV) is studied. A handling improvement algorithm for the normal cornering maneuvers is proposed based on motion tracking control. Considering the ideal assistant power character curves at different velocities, an open-loop DDAS control strategy is developed to respond the driver’s demand of steering wheel torque. The DYC strategy contains the steering angle feedforward and the yaw rate feedback. The steering angle feedforward control strategy is employed to improve yaw rate steady gain of vehicle. The maximum feedforward coefficients at different velocities are obtained from the constraint of the motor external characteristic, final feedforward coefficients are calculated according to the ideal assistant power character curve of the DDAS. Meanwhile, an integral anti-windup PI control is proposed to track reference yaw rate based on linear single track model. In addition, a torque allocation algorithm is proposed to coordinate the driver’s accelerate intention with the additional vehicle yaw moment demand. Simulations and field tests under multiple maneuvers have been carried out. The results indicate that the proposed controller can reduce driver operating burden by decreasing the steering wheel torque while the transient response and the steady gain of the yaw rate are improved. The algorithm can also effectively rectify the under steering caused by accelerating and enhance the handling performance of the DDEV significantly.