Active suppression control of diaphragm-type pneumatic vibration isolators by using FAT-based adaptive controller with fuzzy compensation

This paper develops intelligent control for a diaphragm-type pneumatic vibration isolation (PVI) system. Functional approximation technique (FAT) is integrated with sliding-mode control design to capture unknown system dynamics and release the requirement of mathematical modeling. To deal with approximation error and system dynamics variation, an adaptive fuzzy sliding-mode controller (AFSMC) is employed as a compensator of the FAT-based sliding-mode control. Lyapunov stability theory is used not only to ensure the closed-loop stability but also formulate the updating laws for weighting coefficients of expansion basis and fuzzy tuning parameters. To validate the proposed method, a composite control scheme using pressure and velocity measurements as feedback signals is implemented. Experimental explorations indicate that isolation performances obtained using the proposed FAT-based sliding control augmented with AFSMC compensation (FA+AFSMC) are evidently better than those of the solely AFSMC scheme.