Compensation in Repetitive Control System for Aperiodic Disturbances and Input Dead Zone

This paper extends the equivalent-input-disturbance (EID) approach to deal with the problem of aperiodic disturbance rejection for a plant with an input dead zone in a repetitivecontrol system so as to improve control performance for the tracking of a periodic signal. Since a dead zone greatly degrades control performance, we apply the EID approach to design a compensator for the nonlinearity by treating it as an input-dependent disturbance. An EID estimator is constructed by making the best use of a full-order generalized state observer (GSO). And a method of designing the GSO is explained. The EID estimate, which exhibits the synthetic effect of the nonlinearity and the aperiodic disturbance, is incorporated into a repetitive control law to compensate for the nonlinearity and the aperiodic disturbance. This method does not require any information about the dead zone. It guarantees perfect tracking for periodic reference input and satisfactory compensation of input dead zone and aperiodic disturbance at the same time. Simulation results demonstrate the effectiveness of this method.