Development of Estimation Force Feedback Torque Control Algorithm for Driver Steering Feel in Vehicle Steer by Wire System: Hardware in the Loop

In conventional steering system, a feedback torque is produced from the contact between tire and road surface and its flows through mechanical column shaft directly to driver. This allows the driver to sense the steering feel during driving. However, in steer by wire (SBW) system, the elimination of the mechanical column shaft requires the system to generate the feedback torque which should produce similar performance with conventional steering system. Therefore, this paper proposes a control algorithm to create the force feedback torque for SBW system. The direct current measurement approach is used to estimate torque at the steering wheel and front axle motor as elements to the feedback torque, while, adding the compensation torque for a realistic feedback torque. The gain scheduling with a linear quadratic regulator controller is used to control the feedback torque and to vary a steering feel gain. To investigate the effectiveness of the proposed algorithm, a real-time hardware in the loop (HIL) methodology is developed using Matlab XPC target toolbox. The results show that the proposed algorithm is able to generate the feedback torque similar to EPS steering system. Furthermore, the compensation torque is able to improve the steering feel and stabilize the system.