On the Dual Properties of Friction and Backlash in Servo Control Systems

Abstract

This study provides some insights concerning similarity, reciprocity, and some kind of dual properties between friction and backlash phenomena. It is shown that the friction and backlash models and their describing functions are based on similar analytic descriptions, and, in a certain sense,are dual of each other from a structural standpoint. Hence, the common engineering practice to compensate backlash with friction and vice versa gets a theoretical foundation. The study is primarilyusing the Karnopp stick-slip friction model, and the "exact" physical model of a shaft with backlash.