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

This paper reports about a new actuator combining both a piezoelectric actuator and a pneumatic cylinder for the applications of automatic assembly. The results of fundamental experiments were presented and an analytical model was described. The experimental results show that the proposed actuator could 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 three degrees of freedom (3 DOF) positioning system had been constructed as a practical application. Due to the limited sensing range of the gap sensors, the positioning range had be limited to +/-1 mm, +/-1 mm, and +/-2 mrad along the 3-DOF A heuristic control model was described in the paper. Using this model, a target object made of stainless steel (130 x 100 x 10 mm) was successfully positioned with an accuracy of +/-0.5 mum, +/-0.5 mum,and +/- 20 murad along the 3-DOF. It is shown that the combined piezo-pneumatic actuator has attractive practical applications in the field of precision industry.