DISCRETE-TIME OBSERVERS FOR SINGULARLY PERTURBED CONTINUOUS-TIME SYSTEMS

The use of discrete-time observers for nonlinear singularly perturbed continuous-time systems is explored, The observer design approach is b ased on inversion of state-to-measurement maps, The two-time-scale nat ure of the system is exploited by constructing separate reduced-order observers for the approximate slow and fast subsystems, using multirat e measurements and computation, The reduced-order observers are compar ed to a full-order observer designed for the same system, The comparis on shows that although the reduced-order observers exhibit some approx imation error, they also result in reduced computational requirements if the inversion is performed on-line, reduced memory requirements if the inversion is implemented by look-up table and reduced stiffness. T he trade-off between accuracy and implementation requirements always f avors the reduced-order approach for systems with significant separati on of time scales, Numerical examples are provided, including a case-s tudy of an observer-based control system for permanent-magnet synchron ous motors,