Robust and Adaptive Position Control of Pneumatic Artificial Muscles Using a Fuzzy PD+I Controller

Abstract

This study evaluates the effectiveness of a fuzzy PD+I (FPD+I) controller for robust and adaptive position control of pneumatic artificial muscles (PAMs), addressing the challenges arising from system nonlinearity and hysteresis. Experiments were conducted under varying loads, setpoints, and actuated distances to assess the robustness and adaptability of the controller under diverse conditions. As part of the evaluation, the results were compared with those obtained using a conventional PID controller. The FPD+I controller consistently demonstrated superior transient response characteristics, improved trajectory-tracking accuracy, and greater adaptability to dynamic operational changes. Notable improvements include a 21% reduction in settling time and a 22% reduction in rise time under constant loads, as well as a 49% improvement in root mean square error and a 24% reduction in rise time during trajectory-tracking tasks. The controller also exhibited enhanced resilience to continuous load disturbances and maintained stable performance under varying signal amplitudes. These findings suggest that the FPD+I controller is a promising solution for precision control applications in robotics and industrial systems employing PAMs, particularly in dynamic and uncertain environments, where both robustness and adaptability are critical.