GEOMETRY INDEPENDENT - WIDE RANGE END EFFECTOR
Original Publication Date: 1988-Jun-30
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
Frequently, it is required to unload parts from three turning centers and then place these parts in a specific position for transportation to the next successive operation. It is desirable to utilize a low cost robots to unload all three machines, pick up the parts in the same relative position to the machine chuck, use one end effector, and place all the parts in the same relative conveyance position. To achieve this, the end effector must be able to handle various materials without surface damage, a wide range of diameters and lengths must be compliant and accurate, and must be capable of overcoming forces and moments exerted by the parts and the dynamics of motion. Thus, the robotic end effector must be capable of handling cylindrical stock of a wide range of diameters and lengths. To achieve this, the end effector utilizes multiple grippers simultaneously activated but acting independently to accommodate a variety of shapes. The levers are capable of rotation and maintained within the same plane. They are pivoted such that rotation of these levers will cause the levers to converge about a common centerline and provide the greatest latitude in grasping various sized objects in the smallest amount of space. As shown in the drawing, levers 10 are controlled by return springs 12, ropes 14 and braking mechanism 16. Tension and compliance springs 18 are employed as well as movable plate 20 A handle 22 is utilized to control the foregoing. Normal force attainment, compliance and stability is achieved by driving these levers by the wire rope attached to the spring connected to the movable plate. When the plate is moved, such that the levers are about an object, the plate is moved further so that tension is applied to the rope creating a normal force on the object being grasped. The plate is then moved further so that the brake/pinch mechanism is engaged in position on the wire rope, between the spring and lever holding the wire rope from movement and maintaining the tension on the wire rope by the spring force.