Closed-Loop Iterative Optimized Fractional-Order PID Current Control of PMSM

In the field of robotics, particularly in human–robot interaction, rapid and precise torque control is crucial. This study presents a closed-loop iterative optimized (CIO) approach designed to improve current tracking in servo systems, positioning it as a feasible alternative to traditional proportional-integral controllers. The proposed method innovatively combines a fractional-order proportional-integral-derivative (FOPID) controller with linear matrix inequality (LMI) technique and genetic algorithm in a closed-loop iterative setting. This integration not only boosts the FOPID controller's response speed, but also leverages the robustness of LMI, enhancing stability under various operating conditions. The inclusion of heuristic algorithms in this system enables a more dynamic and efficient search for optimal control parameters, aligning the controller's performance with the complex requirements of contemporary robotics. Experimental data underscore that this approach significantly increases torque response speed and the control system's bandwidth, vital for satisfying the dynamic needs of current robotic applications.