Point-to-point positioning control of a pneumatic muscle actuated system using improved-PID control

Over the past decade, pneumatic muscle actuator (PMA) has been in the limelight and receiving much attention not only in the field of industrial application as well as in prominent research areas such as robotics and biomedical engineering. The uprising can be accorded to the many advantages that PMA offers such as inherent compliant safety, low maintenance and powerful. However, PMA has yet to emerge as disruptor in its application field primarily due to the nonlinear dynamics. Despite these detriments, PMA possesses pronounced prospective to be exploited, especially in the field of rehabilitation robotics. Henceforth, this research is initiated to propose a control structure taking into account the nonlinear dynamics where PMA motion is concerned. An improved proportional-integral-derivative (PID) control is proposed and the effectiveness of the controller in point-to-point (PTP) positioning motion is evaluated experimentally using a single degree of freedom (1-DOF) PMA mechanism. The improved-PID control is constructed with the driving chracteristics of the PMA mechanism. Subsequently, the positioning performance of the improved-PID control is evaluated and compared with a classical PID controller through experimental means. In general, the proposed controller is capable of striking a satisfactory performance in PTP positioning with the reduction of the effect concerning the non-linearities available in the system.