Friction and rigid body identification of robot dynamics

In this paper, an identification method for industrial robots is described that does not require the a priori identification of the friction model. Fi rst, the necessity for such a method is motivated by an overview on convent ional friction modelling and rigid body identification. It is shown that th e time variance of typical friction characteristics lead to systematic iden tification errors. They are avoided by the presented method, which is based on separating the base parameters into three different groups. Each group is identified by simple measurements and a weighted least-squares method. M easurements are carried out with simple motions in the neighbourhood of a n umber of especially selected joint configurations. Further advantages of th is method are its easy implementation for standard robot controls and the p ossibility to find modelling errors. The experimental implementation of thi s method to a typical industrial robot with six rotational joints is carrie d out and yields remarkable results. (C) 2001 Elsevier Science Ltd. All rig hts reserved.