Adaptive Control for a Pneumatic Muscle Joint System With Saturation Input

Pneumatic muscle is a relatively new pneumatic component in some precise and flexible control systems and such systems are needed to achieve a higher controlling performance. However, the existence of practical uncertainties will make it hard to achieve a higher control accuracy and better performance. In this paper, the adaptive control problem for the pneumatic muscle joint system with input saturation, external disturbance and modeling errors is investigated. The auxiliary signals r(1), r(2) and function psi(sgn) as an approximation of sign(.) function is introduced to deal with the unknown saturation and uncertainties caused by modeling errors. Then an adaptive control scheme is proposed by using these auxiliary signals and functions. Finally, simulation studies are used to verify the effectiveness of the proposed control scheme.