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.