Friction generates stick-slip motions and limit-cycle oscillations that significantly deteriorate the position control
performance of the feed drive system. In this regard, various techniques to estimate and compensate the friction have
been proposed to improve the position control performance. The conventional methods have two limitations. Firstly
each feed drive component has different friction characteristics. However, the conventional friction models assume the
feed drive system as a single friction source. Secondly the load applied to the feed drive changes during operation
because of material removal. The change of the applied load causes the change of the friction behavior. However, the
change of the friction behavior is not considered in the conventional friction compensation methods. To solve these
problems, this paper proposed two methods to estimate friction accurately. At first, a distributed component friction
model that considers the friction characteristics of each component independently is proposed. At second, an adaptive
friction compensation controller that estimate and compensate the effect of the applied load on friction is proposed.
Ball-screw type feed drives generally used in machine tools are constructed and experimental results are discussed to
verify the proposed methods.