State-dependent friction force compensation using periodic adaptive learning control

This paper uses the periodic adaptive learning control (PALC) for the compensation of a state-dependent non-Lipschitz external disturbance of electromechanical systems. Theoretically, we are interested in designing a non-Lipschitz friction force compensator, where the friction force is considered position-dependent external disturbance. The key idea of the proposed scheme is to make use of state-periodicity of an external disturbance on the iterative state domain. The state-periodical adaptive compensator designed based on Lyapunov stability analysis guarantees an asymptotical stability of the system after the first iterative trajectory and onwards. The designed-adaptive compensator is verified through an actual DC motor control test.