Improved sliding mode dual hierarchy ADRC method based on electromagnetic linear actuator

Abstract

Electromagnetic linear actuators are widely used in direct drive systems. To mitigate the effects of internal parameter disturbances and external uncertainties, this paper proposes an improved active disturbance rejection sliding mode control method. The position loop employs active disturbance rejection control with an enhanced sliding mode control rate and a dual hierarchy expanding state observer, while the current loop uses Proportional-Integral (PI) control. System stability is verified using Lyapunov theory. The dual hierarchy linear expansion state observer effectively estimates position and velocity, while a terminal complementary sliding mode controller replaces the traditional linear controller to enhance response speed and accuracy, reducing chattering associated with conventional sliding mode control. Simulation and experimental results show that compared with the traditional ADRC and ISM-ADRC, the improved method reduces the steady-state error by 45.5% and 29.4%, respectively. The maximum error at 1 hz and 2 hz sine conditions is 0.50 mm and 0.52 mm, respectively. In addition, the root mean square error (RMSE) was reduced by 15.13% and the maximum error was reduced by 7.4% compared to the traditional ADRC, showing greater robustness under different loads. These results verify the effectiveness and practicability of the proposed electromagnetic linear actuator control method.