A new and innovative concept for the control of backlash in gear-coupled transmission mechanisms. The concept utilizes redundant unidirectional drives to assure positive coupling of gear meshes at all times. Based on this concept, a methodology for the enumeration of admissible redundant-drive backlash-free robotic mechanisms has been established. Some typical two- and three-DOF mechanisms are disclosed. Furthermore, actuator torques have been derived as functions of either joint torques or end-effector dynamic performance requirements. A redundantly driven gear coupled transmission mechanism manipulator has a fail-safe advantage in that, except of the loss of backlash control, it can continue to function when one of its actuators fails. A two-DOF backlash-free arm has been reduced to practice to demonstrate the principle.

U.S. Patent and Trademark Office Description



Lung-Wen Tsai, Sun-Lai Chang

Date Issued


Patent No.