DESIGN OF ANTI-BACKLASH TRANSMISSIONS FOR PRECISION POSITION CONTROL-SYSTEMS

Position control systems typical of machine tools and robots usually operate at relatively high torque and low speed. Although servo motors having these characteristics are now available, their cost, size, and weight generally exceed those of the traditional servo motor and gear reducer. Critical applications require transmissions with zero backlash and high stiffness, for which there are several solutions. This article reviews various anti-backlash techniques, discusses their subtleties and applications, develops models, and presents design methodologies. Although presented in the context of geared transmissions, the ideas also apply to other machine elements and situations requiring precision and robustness. Two case studies, a robot revolute joint and a machine tool axis of rotation, help to reinforce the theory and raise practical issues.