Force Control System for an Electric Gripper
Original Publication Date: 1985-Jul-01
Included in the Prior Art Database: 2005-Feb-18
A technique is described whereby the inherent holding force of grippers, used in robotic arm actuators, is increased by controlling the drive current of the motor used to drive the grippers. Motors used in gripper drive mechanisms have size and weight limitations as well as heat dissipating requirements. This restricts the overall power reflected at the grippers. Also, the combination of linear and rotary bearings, lead screws, gears and various types of preloading will produce a considerable amount of friction. Typically, a 40-pound gripping force would require 32 oz.-in. of continuous applied motor torque. Of the 32 oz.-in., 22 oz.-in. is used just to overcome frictional forces. This requires gripper motors to be too large, limiting the ability of the gripper to reach small spaces.