Abstract:

Presently, with the rapid development of control technology and electronics, automobile intelligence and electronization have become the mainstream trend. The steer-by-wire system cancels the mechanical connection of the traditional steering system, and transmits the driving intention to the steering actuator through the bus, which facilitates the overall layout of the steering system, while optimizing the steering characteristics of the car and further improving the handling stability of the car. Meanwhile, steering by wire is also a key technology for automatic driving to achieve vehicle path tracking and obstacle avoidance.

The main function of the steer-by-wire system is to follow the wheel angle to the steering wheel angle, which requires the steering motor to track the steering wheel angle quickly and accurately. In the meantime, the steering executive motor entirely supplies the driving force for wheel response to the driving intention in the steer-by-wire system. The control of the steering motor serves as the core of the whole control system, determining the quality of the steering performance. This paper focuses on formulating a steering motor control algorithm in line with the steer-by-wire system, aiming to achieve the driver’s steering intention.

Most of the current steer-by-wire systems use brushed DC motors and brushless DC motors as road sense motors and steering motors. Among them, the brushed DC motor is low in power density, easy to spark and has short service life, and when high-power commutation. Brushless DC motor achieves long service life, but has poor low-speed performance, which affects the driver’s driving feel when steering. Although the control of Permanent Magnet Synchronous Motor (PMSM) is more complicated, it has the advantages of high power density, small rotation pulsation, good low-speed performance and long service life, and is suitable for wire control steering motor. However, PMSM is a strong coupling and nonlinear time-varying system. Traditional PID control has its own limitations and weak anti-interference ability, making it difficult to achieve the desired control in PMSM servo control systems. To overcome the weaknesses of PID control strategy, an Active Disturbance Rejection Controller (ADRC) is proposed as a replacement in the speed loop of the PMSM servo control system. ADRC technology is a new control theory proposed by Prof. Han Jingqing based on PID control and modern control theory, resolves the contradiction between overshoot and rapidity in PID control through real-time observation, estimation, and compensation of the input signal transition process and the total internal and external disturbance during system operation. This not only mitigates the defects of PID control but also enhances the system’s anti-interference capability.

This paper designs a motor servo control strategy based on Active Disturbance Rejection Controller. First, the paper builds a mathematical model of the permanent magnet synchronous motor in the rotating alternating axis coordinate system, adopting the rotor magnetic field directional vector control strategy. Second, a second-order Active Disturbance Rejection Controller is designed to mitigate the impact of both internal and external motor disturbances, significantly enhancing its anti-interference capabilities when compared to the PID controller. Addressing the challenges of adjusting parameters for the second-order Active Disturbance Rejection Control, this paper employs fuzzy algorithm to optimize the parameters of nonlinear state feedback controller of ADRC, and designs the position velocity Fuzzy-ADRC of PMSM servo control system. Finally, a motor control model is built in Simulink and a simulation analysis is performed. The control strategy not only overcomes the contradiction between overshoot and rapidity in the controller, but also improves the control precision and anti-interference ability of the whole system. The superiority of the control strategy and algorithm outlined in this paper is verified through simulation.