Abstract: Based on a linearized mathematic model that can reveal the system behaviors more precisely, the system performance with the pressure difference feedback is analyzed theoretically, and it is concluded that the feedback of the pressure difference can improve the dynamic performance but will cause great steady-state deviation. On this basis, a position plus velocity plus derivative of the pressure difference feedback control method (PVDDP) is proposed to improve the control performance of the system, and the validity is analyzed theoretically. Moreover, to avoid the displacement fluctuation phenomenon around the desired position and improve the positioning accuracy, a pressure difference control auxiliary approach is presented. Experimental results show that the pneumatic rotary actuator position servo system with the proposed control method achieves better control performance.

Key words: Pneumatic position servo system, Pressure feedback, State feedback control, Theoretical analysis