Identification of generalized friction for an experimental planar two-link flexible manipulator using strong tracking filter

In this paper, we propose a systematic approach to identify the friction of an experimental planar two link flexible manipulator. The dynamic model of the flexible manipulator, which contains only the first flexible modes of each link and the model of actuators, has been linearized around a definite operating point. Then, a new concept, “generalized friction”, is proposed, and the linearized model is modified to include the generalized friction. A minimal order, linear, time-varying model is obtained. Later, a “strong tracking filter” (STF) is introduced to estimate the time-varying generalized friction at every operating point, based only on a rough model. Although the time-invariant linear model is obtained at a definite operating point, we have shown that it can describe accurately the manipulator´s dynamics in the whole operating area with the aids of estimation of the time-varying generalized friction. Finally, experimental results are presented to demonstrate the effectiveness of the proposed approach