Abstract:   A single degree freedom pneumatic artificial muscle spring mass system was built. The pneumatic artificial muscle is controlled by high speed on/off valve in PWM technique. A hybrid controller is setup to tracking control the pneumatic artificial muscle system which is composed of an adaptive fuzzy CMAC (cerebellar model articulation controller) and discrete sliding mode reaching low strategy. In hybrid controller discrete sliding mode strategy produces the control output; the adaptive fuzzy CMAC is used to approximate the uncertainty of the pneumatic artificial muscle control system. The online self adjustment ability guarantees the approximation ability of the adaptive fuzzy CMAC. Finally, the comparative study of control performance between discrete anti saturation PID (DASPID) and hybrid controller (HybridC) was carried out. The experimental results suggest that the hybridC is better than DASPID. While the desired reference input is sinusoidal, the biggest tracking error of PID is ±15 mm; however the biggest tracking error of the hybridC is only ±07 mm; the average tracking error is about ±02 mm. Furthermore as the main drawback of discrete sliding mode strategy, the chatter phenomenon is greatly reduced. 

Key words: pneumatic artificial muscle, discrete sliding mode, adaptive fuzzy cerebellar model articulation controller (CMAC), hybrid controller, position tracking control