An experimental study into displacement of a shape memory alloy actuated robotic microgripper

Abstract

A parallelogram flexible hinge microgripper design made from aluminium alloy 7075-T6 material has been designed and manufactured with purpose of being able to manipulate a 25 μm diameter platinum wire. The structure is unique in that it is actuated using a shape memory alloy. The actuator circuit is designed so that during operation one microgripper arm remains ridged during the gripping process to ensure a consistent reference point whilst the other gripper arm flexes. The focus of the study is on the shape memory alloys capability in terms of providing the correct jaw displacement and displacement time in relation to the circuit input current. The results show a repeatable relationship between displacement and the applied current. In addition, it was shown that the current across the SMA wire increases it dramatically impacts the time taken for the jaws to close. The displacement time is also due to the resistive mechanical force of the microgripper body during operation. Overall the shape memory alloy actuator and optimised gripper design are shown to be useful for a number of industrial applications.