Active suppression of pneumatic vibration isolators using adaptive sliding controller with self-tuning fuzzy compensation

This paper aims to develop and implement intelligent control for a diaphragm-type pneumatic vibration isolation system. Functional approximation technique (FAT) is integrated with the sliding-mode control (SMC) design to capture the unknown systems dynamics and release the requirement of mathematical modeling. In order to deal with the approximation error caused by truncating the infinite expansion series to a finite sum and the uncertainties of the system, an adaptive fuzzy sliding-mode controller (AFSMC) is used as a compensation of the FAT-based sliding-mode control. Lyapunov stability theory is applied to ensure the closed-loop stability and formulate the updating laws for weighting coefficients of expansion functions and fuzzy tuning parameters. A hybrid control scheme which adopts pressure and velocity measurements as feedback signals is implemented. Experimental explorations indicate that the proposed FAT-based sliding control augmented with AFSMC compensation (FA+AFSMC) outperforms the traditional PID control or solely AFSMC scheme.