2018 Volume 7 Issue 2 Pages 141-149
This paper examines the response dispersion in the micrometer-stroke point-to-point positioning motion of high-precision servo systems with nonlinear friction, and presents an advanced model-based feedforward (FF) friction compensation technique to improve the servo performance. In servo mechanisms with rolling ball bearings and/or guides, rolling friction is well-known to deteriorate not only the transient response but also the settling accuracy, because of the nonlinear and complicated friction properties in the micro-displacement region. Therefore, effects of the rolling friction on the performance deterioration should be carefully considered to perform precise simulation analyses and to design effective controllers. In this study, first, the mechanism of response dispersion in the micrometer-stroke motion is analyzed in detail through numerical simulations using a rolling friction model. Then, an advanced FF friction compensation technique using the rolling friction model is adopted with consideration of the mechanism of response dispersion. The effectiveness of the rolling friction model-based analyses and the friction compensation are demonstrated for a laboratory prototype linear motor-driven table system.
