Pneumatic actuating device with nanopositioning ability utilizing PZT impact force coupled with differential pressure

This paper reports a new actuating method using piezoelectric (PZT) impact force coupled with differential pressure for the pneumatic positioning device. Fundamental experiments show that the sliding table can be actuated to move with precise step motions in both the forward and backward directions based on the proposed method. A two degree-of-freedom (DOF) analytic model is established and verified for expressing the impact actuation. Furthermore, a pulse width, which is equal to the period of second-mode vibration of the actuating device, is experimentally examined for the actuation of PZT actuator. Finally, position control based on a hybrid controller is implemented. The experimental result shows that the sliding table is successfully positioned from the reference origin to the target position of 4 mm in 0.924 s with the positioning accuracy of 5 μm due to the actuation of the pneumatic cylinder, and that the final positioning accuracy of 10 nm is obtained by the actuation of PZT impact force coupled with differential pressure. The total control time is 2.683 s. It is shown that the proposed method is capable of significantly improving the positioning performance of the pneumatic actuating device. It is expected that the proposed method will be widely applied in the precision industry using pneumatic cylinders.