State and unknown input estimation for a class of infinitely unobservable descriptor systems using two observers in cascade

Design of unknown input fractional order proportional–integral observer for fractional order singular systems with application to actuator fault diagnosis

“…The observer gain matrices S, T 2 and G can be calculated from (35), (30) and (22), respectively. Finally, the matrices H and L are deduced from (24) and (25). The Matlab CVX interface [42] to SDPT3 [43] is used for solving the optimisation problem.…”

“…Obviously, the usages of restricted equivalent transformations are not desirable from the viewpoint of computation. It is worth mentioning that there exist some recent works on fault diagnosis of infinitely unobservable singular systems [24,25]. It should be pointed out that, in most existing results, only square singular systems have been considered under the regularity condition.…”

Impact time and angle constrained integrated guidance and control with application to salvo attack

“…The Walcott-Zak observer [25] has been traditionally proposed to achieve state estimation robustly against disturbance signals, but it only achieves asymptotic convergence. Subsequently the Edwards-Spurgeon observer [26] improves on it, where the disturbances can be estimated (and therefore popularly used in fault estimation works [27][28][29]), but again only achieves asymptotic convergence, whereas the differentiator (14) achieves finite-time convergence of estimation errors.…”

On sliding mode observers for non-infinitely observable descriptor systems

“…Due to these characteristics, the descriptor system can represent a wider range of systems such as electrical circuits, biological systems, constrained mechanics, chemical processes and so on [4]. Although there have been fruitful results in general observer design for descriptor systems (see [5][6][7][8] and references therein), only few works have used SMOs [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Note that in [9][10][11][12][13][14][15] the so-called infinitely observable condition (IOC) was required to be satisfied, which might be a restrictive condition for many physical systems, such as electrical circuits [23] and the chemical systems [20] which are non-infinitely observable (NIO).…”