Performance robustness of MRAC under reduction in actuator effectiveness

The problem of performance robustness of model reference adaptive control (MARC) schemes under reduction in actuator effectiveness (loss-of-effectiveness) is studied in this paper. The reduction is modeled by an uncertain gain matrix representing the actuator effectiveness at the control inputs. MRAC systems are analyzed to determine the robustness of the desired closed-loop performance of stability and asymptotic tracking with respect to such reductions. Conclusions are drawn for direct multivariable MRAC as well as indirect MRAC for both continuous-time and discrete-time schemes. A simulation study is presented to illustrate some of the theoretical results.