ACCURATE AND ROBUST ADAPTIVE HYPERBOLIC-PID CONTROL STRATEGY FOR A SERVO PNEUMATIC SYSTEM

Abstract

Robust trajectory tracking and precise positioning remain critical challenges in servo pneumatic actuator systems, particularly under varying external load conditions. Conventional PID controllers, while widely adopted, often struggle with nonlinearities and internal disturbances such as friction. This study presents a comparative analysis of three advanced control strategies—PID with static friction compensation (PID+F_SS), Nonlinear Hyperbolic PID with F_SS (NH-PID+F_SS), and Triple Nonlinear Hyperbolic PID integrated with Single-Input Fuzzy Logic and Generalized Maxwell Slip friction compensation (T-NPID+SIFLC+F_GMS). The controllers are evaluated on a 100 mm amplitude sinewave trajectory at 0.1 Hz under no loading (0 kg), 1 kg, 5 kg, and 9 kg external loads. Design validation is grounded in the asymptotic tracking region (ATR) framework, ensuring convergence of error to zero and stability. Performance is quantified using maximum tracking error (MTE) and root mean square error (RMSE). Experimental results demonstrate that T-NPID+SIFLC+F_GMS achieves superior tracking accuracy and robustness, with up to 48.84% improvement in the measured performance compared to baseline PID+F_SS. The findings affirm the efficacy of integrating adaptive fuzzy logic and advance nonlinear PID. Future work will explore the comparison of the different friction compensation module (F_GMS and F_SS) effecting the control strategy.