Design and Analysis of a Compliant Gripper Integrated with Constant-Force and Static Balanced Mechanism for Micro Manipulation

Abstract

There is a huge demand of manipulating delicate micro objects in various fields such as biotechnology, micro electro mechanical systems (MEMS). However, due to the uncertainty in sizes and stiffness of those micro objects, it makes this task more challenging. Those systems have rigorous requirements for the regulation of the output force from the gripping tool. Apparently, the use of sensors and feedback systems makes the mechanism both complicated and cost intensive. This paper presents a novel design concept of a gripper which can manoeuvre objects in various sizes but it still can preserve a constant gripping force by integrating a constant force mechanism. No sophisticated sensors and control systems are required for the design thanks to the usage of compliant mechanism. The passive type integrated compliant constant force mechanism exhibits its characteristics from combined compression and bending of beam structures. The design methodology of this compliant constant-force gripper mechanism (CFGM) using genetic algorithm shape optimization is presented. Finite element analyses are used to characterize the constant-force behavior of the gripper under static loading. A design formulation is proposed to find the CFGM shape for a specified gripping range with constant output force of the mechanism. The benefits of the monolithic nature of the compliant mechanism would also extend the miniaturization possibility of the CFGM as a micro-gripper for MEMS applications.