Precision positioning device utilizing impact force of combined piezo-pneumatic actuator

This paper reports on a new actuator combining both a piezoelectric actuator and pneumatic cylinder for the automatic assembly application. The results of fundamental experiments are presented and an analytical model is described. The experimental results show that the proposed actuator can move a target object with step sizes in the 10-nm order by utilizing the impact force of a piezoelectric element while maintaining the comparatively long operation range of a pneumatic cylinder. Furthermore, a 3-DOF positioning system had been constructed as a practical application. Due to the limited sensing range of the gap sensors, the positioning range is limited to ±1 mm, ±1 mm, and ±2 mrad along the 3-DOF. A heuristic control model is described. Using this model, a target object made of stainless steel (130×100×10 mm) was successfully positioned with an accuracy of ±0.5 μm, ±0.5 μm, and ±20 μrad along the 3-DOF. It is shown that the combined piezo-pneumatic actuator has attractive practical applications in the field of precision industry