Design and control of a novel asymmetrical piezoelectric actuated microgripper for micromanipulation

Microgripper is an important tool in high precision micromanipulation task, which directly affects the quality and efficiency of micromanipulation. This paper presents the design and control of a novel asymmetrical microgripper driven by a piezoelectric (PZT) actuator. The developed microgripper is designed as an asymmetrical structure with one movable jaw, so it has the advantages of no dense mode and fixed locating datum compared with the symmetrical microgripper with two movable jaws. The main body of microgripper is a compact flexure-based mechanical structure with a three-stage amplification mechanism. Based on the three-stage amplification structure, large-range, robust and parallel grasping operation can be realized. The characteristics analyses of the developed microgripper are carried out by finite element analysis (FEA). A position-force switching control strategy is utilized to regulate the position and grasping force of movable jaw. Discrete-time sliding model (DSM) controller is designed to control the position and grasping force. Experimental studies are conducted and the experiment results show that the microgripper exhibits good performance and high precision grasping operations can be realized through the developed control strategy.