Development of a Force Sensitive Robotic Gripper

Abstract

The nuclear industries often use robotic arms in master-slave manipulators. Here, the range of instruments and objects that the gripper may be required to handle vary significantly on case to case basis. Often a robotic arm's end-effecter has to grip sensitive instruments and tools for carrying out inspection or some 'operation' in 'hot' areas. Other times it may have to handle heavy tools or parts to perform assembly or fabrication tasks. The robotic arms are expected to grasp these devices, some of them quite delicate, using its grippers gently, yet firmly. This calls for a gripper that is gentle yet smart enough to hold unknown objects without letting it slip. The problem is to grasp the objects without knowing its weight or surface friction in advance. This requires the detection of slip well in advance --before it becomes unmanageable, particularly when the arm is in motion generating centrifugal forces. In other industries, the robotic arms are used exclusively for some repetitive fixed tasks and they need to apply just a fixed gripping force, well calibrated for handling only a specific object. Naturally, commercially available grippers do not offer controlled gripping feature. We propose in this paper, a slip-less gripper that works by acquiring the information about the forces acting on the object in real time.