A Servo Control Gripper Design

[Abstract] A servo-control gripper is designed to replace a pneumatic-control gripper for a PUMA robot. The two-finger gripper is driven by a DC servo motor and a gear-and-rack mechanism. An E2KX4M capacitance proximity sensor is mounted to one side of the finger. When an object is sensed by the proximity sensor, a signal is sent to the controller, which will send a signal to the DC servo motor to slow down the closing speed of the finger. In addition, a spring pad and an LVDTdisplacement sensor are mounted on the other side of the gripper to control the gripping force. When a specified amount of movement is sensed from the LVDT through an A/D converter, the controller sends a signal through a power amplification system to stop the movement of the gripper. Therefore, the gripper is able to grasp a fragile and brittle object, such as an egg, without cracking it. The design can increase the programming capability of the gripper and is very economical when compared to the purchase of the servo-control board directly from the robot company.