Plenary lecture VIII: mathematical models of grippers

In robotics technology, the groups belong to the functional units have the greatest variety of design. This is due to the fact, although the robot is a flexible machine, the gripper performs a much more tasks. Nevertheless, these tasks are not limited to prehension only which is why the more generic term end - effector is often used. Many grippers are used in the loading of the manufacturing lines, in packaging and storage as well as the handling of objects in laboratory test and inspection systems. Grippers constitute the end of the kinematic chain in the joint systems of the industrial robots, and facilitate interaction with the work environment. Although universal grippers with large holding can be used for diverse work piece shapes, in many cases they must be adapted to the specific work piece shapes. On the whole, there are many types of grippers. Each of these is specialized in holding of a certain shape of the work piece. Unfortunately, there are few types of universal grippers, which can not grasp any object. In this way it is necessary that a single gripper to grasp work pieces with different dimensions. The most work pieces are cylindrical ones. If the robot handle the cylindrical work piece with various diameters, it is necessary that all pieces to be fixed with their axes in the same position. The self centering grippers can have two or three fingers. They are commonly used for the handling of cylindrical work piece in loading and mounting operations. The fingers may have the rotational or translational movements. If the gripper has two fingers with rotational movements, the active surfaces of the jaws are noncircular shapes. The jaws of the grippers with three fingers have the plane or circular cylindrical shapes, but the driving system has a cam with translational movement. In the work, some considerations with regard to design of the self centering grippers used to handle the work piece with cylindrical shape are presented.