Adaptive Fractional Order PID Controller for Angle Tracking In Steer -By -Wire System

To ensure fast and accurate angle tracking during car steering, reduce delay time, and improve the tracking performance of the Steer-by-Wire (SBW) system, a fractional order PID (FOPID) controller with feedforward compensation is designed. The PID controller is approximated using the Oustaloup approximation method, reducing the tuning dimension of FOPID. An improved particle swarm optimization (PSO) algorithm is utilized to dynamically adjust the four parameters of FOPID, thereby decreasing the optimization time of the algorithm. Finally, the Adaptive Inertia Weight Particle Swarm Optimization algorithm (AW-PSO), based on global search pattern, the Fixed Inertia Weight Particle Swarm Optimization algorithm (F-PSO), based on variable neighborhood search pattern, and the Compressed Factor Particle Swarm Optimization algorithm (CF-PSO) are used as comparisons for simulation verification and bench test. The effectiveness of the proposed method is verified. The comparative results show that, in terms of computation time and accuracy, the optimization capability of the proposed method is significantly superior to the AW-PSO, F-PSO, and CF-PSO algorithms. Hence, the algorithm's computation accuracy and stability fully meet the requirements. The bench test results reveal that under step input, the delay time is about 0.2s, with a maximum overshoot of 1.57deg. Under sinusoidal input, the delay time is approximately 0.02s, the maximum steering speed is 0.70rad/s, and the maximum output torque of the steering motor is 2.27Nm. Based on experimental verification, it can be possible to conclude that this method enables better completion of the angle tracking control task for the SBW system and exhibits good robustness and tracking control performance