Comparative Study of Electro-pneumatic Actuator Performance Using Linear, Sliding Mode and Hybrid Position Control Laws

摘要

This paper presents a comparative study of linear, sliding mode and hybrid control laws for an electro-pneumatic actuator in the context of position control. The linear controllers include gain-scheduled-proportional-velocity-acceleration and proportional-derivative. The sliding mode controllers include first, second and third order sliding mode control laws. The hybrid controllers are combinations of linear and sliding mode control laws. More precisely, two hybrid controllers have been designed, the first uses gain-scheduled-proportional-velocity-acceleration control law as sliding variable for the first order sliding mode controller, and the second considers the proportional-derivative control law as sliding variable for the second order sliding mode controller. The experimental results showed that the hybrid control laws improve the robustness of the first and second order sliding mode control; also they improve time and frequency response characteristics of the closed-loop. The analysis of experimental results showed the performance of each control law. The main conclusion of results analysis is that the third order sliding mode control law realizes better bandwidth and the second hybrid control law realizes better settling time under load and better position accuracy besides the good bandwidth and the ease of implementation.