The analysis for the reason of limit cycle generated by friction in servo system

In this paper, limit cycle which results from friction during low-velocity servo system has been discussed. First, the piecewise linearization method has been applied to change nonlinear stribeck model to linear model. Second, with analysis of equilibrium property, it is proved the existence of limit cycle and its certain region. The analysis reveals that it is because of stability of equilibrium repeatedly changing results in the limit cycle during low-velocity state. In addition, it also points that the key point to avoid this phenomenon is to keep robust stability of the close-loop system.