Fuzzy Optimal Control for Harmonic Drive System with Friction Variation with Temperature

In this paper, the control problem of the harmonic drive system operating in temperature varying environment is discussed. Based on the fuzzy model of friction changing with temperature, the harmonic drive system dynamics is modeled as a fuzzy Takagi-Sugeno (TS) system of both temperature and velocity. The optimal controller design for fuzzy TS system is presented in an optimization problem subject to linear matrix inequality (LMI) constraints. Multiple positive definite matrices obtained from the optimization, are combined using fuzzy inference to build the Lyapunov matrix to guarantee the stability of the closed-loop system. The performance of the controller is verified through the simulations on reference tracking of harmonic drive system in a temperature varying environment.