Design, Fabrication and Intelligent Control of the Gripper Based on SMA Actuators

Abstract

This paper presents the designing, simulation, fabrication and control of a gripper actuated by Shape Memory Alloy (SMA) wire. The presented gripper has the advantage of the small linear displacement of the slider connected to the SMA wire, and can convert the linear displacement into angular movement of the gripper fingers. In this study, design and simulation processes have been done by two powerful CAD and quasi-real dynamic simulation software; DS.CATIA and MSC.ADAMS respectively. Then, a gripper that actuated by SMA wire has been fabricated and the physical prototype and its mechanical and electrical properties have been presented. Finally, several experiments have been designed and performed, and the results for tip displacement of the fingers are presented and discussed. The results show that the prototyped gripper is performing to a satisfactory extent; as the fingers have been returned to their initial positions with a proper accuracy and also without any feedback control. To compensate the hysteresis phenomenon derived from SMAs wire, self-tuning fuzzy PID method was used to control the force. At first, this method has been applied on the model of the gripper by co-simulation of MATLAB and MSC.ADAMS. After that, the presented controller has been developed on the physical prototype of the gripper and its efficiency has been investigated. The experimental results demonstrate good performance of the designed controller for the tracking of the gripping force.