Generalized-Extended-State-Observer-Based Repetitive Control for MIMO Systems With Mismatched Disturbances

This paper concerns the problem of designing a modified repetitive-control system based on a generalized extended state observer (GESO) for a class of multi-input, multi-output systems in the form of a nonintegral chain and with mismatched disturbances. A GESO is constructed to estimate a lumped disturbance in a real-time fashion. Then, an improved repetitive control law is developed to attenuate the influence of the lumped disturbance from the output channel. A correction to the amount of the delay of the repetitive controller is introduced to further reduce the steady-state tracking error. A stability criterion and a design algorithm are presented. Finally, simulations and comparisons with other methods demonstrate the validity of this method.