Tactile feedback control for a gripper driven by SMA springs

This paper presents a gripper actuated by a pair of differential shape memory alloy (SMA) springs with the tactile feedback controller of the polyvinylidene fluoride (PVDF) films. The SMA actuator is heated by the electric current and cooled by the fans, and a proportional-integral (PI) controller is proposed to control the output position of the gripper. In order to handle soft, deformable or slippery objects very well, the PVDF sensor is added to the finger of the gripper to perform the tactile feedback when it grasps the objects. The hardware system is established including data acquisition and signal processing parts, the control system is programmed. Experiments of grasping a soft object are carried out, and the gentle grasp ability of the gripper is also tested. Experiments results show that the SMA gripper with the PVDF tactile sensor could grasp a soft object through controlling tactile forces.