Design of multirate observers and multirate control systems

In this paper, the design problem of the observer-based multirate control system is considered. First, a reduced-order observer of the current type is proposed on the basis of the mode-decoupling transformation. It is shown that, under the multirate measurement, the state estimates can be achieved by two low-order multirate observers which possess the hierarchical structure. Second, the multirate control system incorporating such reduced-order observers is studied. Furthermore, a design problem of the multirate observer which runs in its natural time scale is investigated. Finally, in order to verify the validity of these results, an application to the longitudinal control problem of an aircraft is given.