Non-conventional method for friction compensation in DC drive position tracking

Abstract

Friction, especially its nonlinear components, may degrade the tracking performance of any servo drive systems. Focused on high precision positioning of DC electrical drive the paper proposes an easy method to compensate for the friction by using a non-model based compensator developed around a simple control structure. The approach to inhibit the friction influence is based on a compensation signal provided by the mathematical model of the servo positioning DC drive in which the load torque (including friction component) is considered zero. Build on the difference between the command signals of real servo tracking drive and, respectively, of the same servo drive, but no load status, the compensation variable depends only on the usual and measurable states of an electrical drive (current and velocity) The control problem of the servo drive with friction is solved via the gain scheduling of a P controller parameter as function of position reference scale. Good results concerning the tracking errors are achieved for large range of reference test signals, including the micrometer scale.