Identification of single flexible-joint robot dynamics: a nonparametric approach

In this paper, a nonparametric identification method is used to identify the dynamic model of a flexible joint robot (FJR) that includes friction and transmission nonlinearities. More precisely, the Best Linear Approximation (BLA) approach has been considered in a closed-loop setup to provide the frequency response of the system and an evaluation of the nonlinearities. Based on simulated data, the paper investigates the tuning of an adequate multisine excitation signal that enables good identification results. First, an algorithm is adapted in order to shape the spectrum of the control signal adequately. Second, based on an evaluation of the effects on the Coulomb friction and transmission nonlinearity, it is showed that an optimal amplitude can be found.