Improvement of Positioning Performance of AZARASHI (Seal) Mechanism with Three Degrees of Freedom

Abstract

This paper deals with a reduction method of the straightness error of a small mobile device, “AZARASHI (Seal) Mechanism," with three degrees of freedom. This device consists of two controlled Electromagnets A and B connected by two Piezoelectric actuators with Electromagnet C that generates a constant friction. The friction at Electromagnets A and B are changed by on-off control. The whole device wriggles with Electromagnets C when Piezoelectric actuators extend and contract. The displacement in the experiments are corresponding with the displacement analyzed by solving the equation of motion. The off-friction force generates the moment so that the device is rotated. According to the analytical results, the driving method was improved to reduce the straightness error. In this method, both Piezoelectric actuators are driven in the same way. Then the moment was canceled out and the device was seldom rotated. Consequently, the device could move with less straightness error.