A Self-Sensing Microgripper Module With Wide Handling Ranges

A compliant two-fingered microgripper is designed, fabricated, and demonstrated. To mimic human finger actuation, the proposed finger is distributively actuated by a shape memory alloy (SMA) wire. An SMA-actuated finger model is presented to predict SMA strain and finger motion given its contraction force. Based on this model, the finger shape and SMA wire dimension are optimally designed. The gripper is shown to have a wide handling range, high mechanical advantage, and sufficient out-of-plane stiffness; thus, it can accommodate objects of various sizes and weights. To control its motion, the SMA contraction force is estimated by using the proposed force to electrical resistance model. Gained from the simple driving electronics and self-sensing of SMA, the fabricated gripper can be made compact and lightweight. Finally, a self-powered gripper module is attached to a robot arm to perform several illustrative manipulations.