Design and Control of a Compliant Microgripper With a Large Amplification Ratio for High-Speed Micro Manipulation

TLDR

The paper presents a piezoelectric‑actuated compliant microgripper designed to enable fast, precise, and robust micro‑grasping. The gripper employs a three‑stage flexure‑based amplification (homothetic bridge and lever mechanisms) with optimized geometry, fabricated by wire EDM, and is controlled via a dynamic model‑based position/force switching strategy combining PID and sliding‑mode control. Experiments demonstrate a 22.6× amplification factor and confirm that the microgripper achieves fast, precise, and robust grasping operations.

Abstract

The design and control of a novel piezoelectric actuated compliant microgripper is studied in this paper to achieve fast, precise, and robust micro grasping operations. First, the microgripper mechanism was designed to get a large jaw motion stroke. A three-stage flexure-based amplification composed of the homothetic bridge and leverage mechanisms was developed and the key structure parameters were optimized. The microgripper was manufactured using the wire electro discharge machining technique. Finite element analysis and experimental tests were carried out to examine the performance of the microgripper mechanism. The results show that the developed microgripper has a large amplification factor of 22.6. Dynamic modeling was conducted using experimental system identification, and the displacement and force transfer functions were obtained. The position/force switching control strategy was utilized to realize both precision position tracking and force regulation. The controller composed of an incremental proportional-integral-derivative control and a discrete sliding mode control with exponential reaching law was designed based on the dynamic models. Experiments were performed to investigate the control performance during micro grasping process, and the results show that the developed compliant microgripper exhibits good performance, and fast and robust grasping operations can be realized using the developed microgripper and controller.