Actively controlling the contact force of a stick-slip piezoelectric linear actuator by a composite flexible hinge

Abstract

Stick-slip piezoelectric actuators have been widely employed in those fields where both large working stroke and high positioning accuracy are required. However, the problems of backward motion and relatively low load capability limit their applications, and these two problems are usually contradictory. Attempted to solve these two problems at the same time, in this study, a composite flexible hinge was designed to actively control the contact force between the driving foot and the slider of a stick-slip piezo-driven linear actuator. To confirm the validity, a prototype actuator was designed and fabricated. The dimensions of the actuator in X, Y and Z directions are about 80 mm, 60 mm and 20 mm, respectively. The output characteristics of the actuator were evaluated by experiments. The results showed that without the active control of the contact force, the maximum speed being free of external load were 1.39 and 2.18 mm/s when the driving frequencies were 100 and 200 Hz, respectively. Correspondingly, the maximum horizontal loads of the actuator were 25 g and 50 g, respectively. However, with the active control of the contact force, the maximum speed were 1.74 and 4.1 mm/s under the driving frequency of 100 and 370 Hz, respectively. Moreover, the maximum horizontal loads under 100 Hz and 200 Hz were improved to be 40 g and 70 g, respectively.