Passive Actuator-Less Gripper for Pick-and-Place of a Piece of Fabric

In this article, we propose a Passive Actuator-Less Gripper (PALGRIP) for picking a piece of fabric from a stack of fabric parts and placing the picked fabric part. The picking of a piece of fabric from a stack is a simple but difficult process to automate. The proposed gripper can pick a piece of fabric from the stack by simply pressing the fingertips of the gripper against the stack. The fingers are closed and opened by the relative motion between the fingers and the housing of the gripper. The grasping motion of the gripper is generated by two mechanisms: a passive pinching mechanism and a self-locking mechanism. These mechanisms allow the fingers to perform opening and closing movements and to maintain the fingers in either open or closed state. The kinematics of the mechanisms are analyzed to design the gripper. The relation between the movement of the fingers and the force required to operate the gripper is also investigated through static force analysis and the experiment. Finally, experiments using PALGRIP are conducted, and the experimental results illustrate how the pick-and-place operations are carried out using the prototype of PALGRIP. The proposed gripper allows the robot to automate fabric pick-and-place operations easily by attaching it to the robot's endpoint.