Model-based Design of Reconfigurable Compliant Gripper Actuated with SMA Springs

Abstract

Shape memory alloy (SMA) springs find extensive application in flexible actuation due to their significant capacity for deformability. However, each individual SMA spring only provides limited deformation modes, which prevents the SMA spring based grippers from applying in complicated grasping scenarios. In this study, a reconfigurable compliant gripper with multiple SMA springs is proposed to achieve multifunctional grasping tasks and large motion range. The proposed gripper uses multiple SMA springs for actuation, integrated in segments as building units to shape the gripper fingers. Also, the complete reconfigurable system was designed to accommodate for multiple compliant gripper fingers for flexibility. The reconfigurable compliant gripper is designed by numerical modeling and validated with lad-scaled experiments. The coupling method of Finite Element Analysis (FEA) and Multi Body Dynamics (MBD) was introduced in the modelling of the gripper. The results indicate that the numerical model shows very similar behavior as the experiments. Then, the multiple SMA spring allows for multidirectional bending behavior across the range of bending angle from 0 to 124 degrees. The reconfigurable compliant gripper system can grasp objects of different shapes and weights. Thus, the proposed reconfigurable compliant gripper can lead to a series of novel design solutions for different scales of grasping tasks.