Friction and rigid body identification of robot dynamics

In this paper, an identi®cation method for industrial robots is described that does not require the a priori identi- ®cation of the friction model. First, the necessity for such a method is motivated by an overview on conventional friction modelling and rigid body identi®cation. It is shown that the time variance of typical friction characteristics lead to systematic identi®cation errors. They are avoided by the presented method, which is based on separating the base parameters into three di€erent groups. Each group is identi®ed by simple measurements and a weighted least-squares method. Measurements are carried out with simple motions in the neighbourhood of a number of especially selected joint con®gurations. Further advantages of this method are its easy implementation for standard robot controls and the possibility to ®nd modelling errors. The experimental implementation of this method to a typical industrial robot with six rotational joints is carried out and yields remarkable results