Mixed H2/H∞ PID tracking control design for uncertain spacecraft systems using a cerebellar model articulation controller

A mixed H₂/H_∞ tracking control design method for uncertain spacecraft systems with guaranteed control performance is examined. A mixed H₂/H_∞ controller incorporating a cerebellar model articulation controller (CMAC) learning method and sliding-mode control action is developed in uncertain spacecraft systems under plant uncertainties and external disturbances. The CMAC control system is used to adaptively estimate the non-linear uncertainties, yielding a controller that can tolerate a wider range of uncertainties. The sliding-mode control action is included to eliminate the effect of approximation error via CMAC control system approximation. The sufficient condition is developed for mixed H₂/H_∞ performance in terms of linear matrix inequality formulations. The proposed method is simple and the PID parameters can be obtained systematically. Simulation results indicate that the mixed H₂/H_∞ performance can be achieved using the proposed methods.