Output Feedback of Uncertain Multi-Input Systems

This chapter evaluates output feedback of uncertain multi-input systems. Similar to the case of single-input delay, the result of multi-input delays obtained in the chapter is not global, as it does not believe the problem where the actuator state is not measurable and the delay value is unknown at the same time is solvable globally, since the problem is not linearly parameterized. In a practical sense, the stability result proven in the chapter is not a highly satisfactory result since it is local both in the initial state and in the initial parameter error. This means that the initial delay estimate needs to be sufficiently close to the true delay. Under such an assumption, one might as well use a linear controller and rely on robustness of the feedback law to small errors in the assumed delay value. Nevertheless, the chapter presents the local result here as it highlights quite clearly why a global result is not obtainable when both the delay value and the delay state are unavailable.