Sliding-mode control of a flexure based mechanism using piezoelectric actuators

Abstract

Abstract-The position control of designed 3 PRR flexure based mechanism is examined in this paper. The aims of the work are to eliminate the parasitic motions of the stage, misalignments of the actuators, errors of manufacturing and hysteresis of the system by having a redundant mechanism with the implementation of a sliding mode control and a disturbance observe. x-y motion of the end-effector is measured by using a laser position sensor and the necessary references for the piezoelectric actuators are calculated using the pseudo inverse of the transformation matrix coming from the experimentally determined kinematics of the mechanism. The effect of the observer and closed loop control is presented by comparing the results with open loop control. The system is designed to be redundant to enhance the position control. In order to see the effects of the redundant system firstly the closed loop control for active 2 piezoelectric actuators experiments then for active 3 piezoelectric actuators experiments are presented. As a result, our redundant mechanism tracks the desired trajectory accurately and its workspace is bigger.

A Novel Analytical Model for Flexure-based Proportion Compliant Mechanisms

“…In the fields of micro-scale and nano-scale technologies, most of the researchers are focusing on research and development of smaller and higher precision positioning devices, see Acer [2012], . These devices are utilized in various high precision applications such as automotive, aerospace, telecommunications, medical, biology, optics, and computer industries, see Lobontiu [2003].…”

“…Tian [2010] et al described the mechanical design and dynamics of a 3-DOF(degree of freedom) flexure-based parallel mechanism. Acer [2012] et al designed a 3-PRR flexure based mechanism and investigated its position control. Whereinto, the prismatic ( P ) pair is fulfilled by means of a four-bar linkage.…”