Modelling end-of-roll dynamics in positioning servos

Abstract

End-of-roll dynamics is a characteristic of pointing systems and positioning servos when change in movement direction occurs. Factors such as backlash and friction cannot be easily controlled nor predicted under these circumstances, and although an accurate model for friction exists, the literature is still lacking of a representation for the integrated effect backlash and friction dynamics in these loops. This paper proposes a new mathematical model to represent backlash effects in positioning servos demonstrating its accuracy to predict tracking errors of a naval gun mount. The model introduces a continuous hysteresis representation, different from classical discontinuous models, showing a behaviour closer to what has been observed empirically. The new model can be useful for high performance positioning servo-control applications. (C) 2003 Elsevier Science Ltd. All rights reserved.