Nonmodel-based estimation of friction forces with acceleration estimator

In this paper, we design an adaptive estimator for the nonlinear dynamic friction force when the output is the position. To begin with, a velocity estimator is proposed based on the adaptive identification method. Then, an acceleration estimator is proposed with the non-passifiable adaptive schemes. Finally, the proposed acceleration estimator is applied to the estimation of friction forces. Numerical examples are given to illustrate the performance of the estimator in the case of the viscous friction model, the Coulomb friction model, and the LuGre model.