A Compound Control for Hybrid Stepper Motor Based on PI and Sliding Mode Control

The utilization of closed-loop control in stepper motors has become prevalent in scenarios requiring high-precision control. In this paper, classical proportional-integral (PI) and sliding mode control (SMC) are combined, and a compound control strategy based on the vector closed-loop control of stepper motors is proposed. The primary advantage of this approach is its ability to harness the precision of PI control and the robustness of SMC, mitigating the limitations of each method when used independently. A key innovation is the introduction of an automatic weight adjustment mechanism, which allows adaptive modulation of the two control strategies based on varying operating conditions, ensuring that the two algorithms work together in a coordinated manner. Simple fuzzy logic is implemented for automatic weight adjustments, and a smoothing mechanism is incorporated to prevent instability arising from swift weight adjustments. Simulations were conducted using MATLAB/Simulink to distinctly assess the speed and position control of stepper motors and compare them with those of individual PIs, SMCs, and adaptive network-based fuzzy inference system intelligent controllers. The results indicate that the compound control demonstrates a swifter speed response, a diminished steady-state error, and robust anti-interference capabilities. These results confirm the effectiveness of the compound control strategy in applications where both precision and robustness are paramount.