On emulated nonlinear reduced-order observers for networked control systems

Abstract

We consider a general class of nonlinear reduced-order observers and show that the global asymptotic convergence of the observation error in the absence of network-induced constraints is maintained for the emulated observer semiglobally and practically (with respect to the maximum allowable transmission interval) when system measurements are sent through a communication channel. Networks governed by a Lyapunov uniformly globally asymptotically stable protocol are investigated. Our results can be used to synthesize various observers for networked control systems for a range of network configurations, as we illustrate it by considering classes of immersion and invariance observers which include the circle-criterion observers.

Tracking Control for Nonlinear Networked Control Systems

“…Building upon the analogies which exist between masterslave synchronization and observer design [12], we also derive new results for the observer design problem for NCS. Compared to [13], [14], we rely on a Lyapunov-based analysis (as opposed to trajectory-based arguments) and we provide a new bound on the MATI. In addition, we envision an emulation procedure similar to [15] which allows us to relax some of the assumptions of [13], [14] for the considered class of systems.…”

Observer Design for Nonlinear Networked Control Systems With Persistently Exciting Protocols

“…= ζ y −ζ yz corresponds to the network induced error on the observation error y − y z . Note the difference between the network-induced errors appearing in (22) and in (8). The network-induced errors in (20) and (21) are useful to model scheduling in WH networks.…”

“…Newer results on observer design of NCSs that rely on a Lyapunov-based analysis can be found in [7], in which the authors obtained a new MATI bound via an emulation procedure and a class of protocols that includes uniformly globally asymptotically stable (UGAS) protocols. The design of reduced-order observers via emulation in NCSs is studied in [8].…”

“…Within this framework, plants whose dynamics are affected by disturbances and measurement noise are considered, which are more general and induce additional technical difficulties compared with the aforementioned literature. In [6]- [8], the UGES/UGAS property imposed on the protocols was shown to be key in the convergence of the estimation error. However, this property is quite strong as it requires more information than is typically available (NCS state information).…”

Continuous observer design for a class of multi-output nonlinear systems with multi-rate sampled and delayed output measurements

“…Therefore, observer design for continuous systems with sampled and delayed output measurements has attracted the control community wide attention. There exist three main approaches to design observer for continuous systems with sampled and delayed measurements, for example, discrete time analysis based on a discretized model (Arcak and Nešić, 2004;Barbot, Monaco and Normand-Cyrot, 1999;Nešić, Teel and Kokotović, 1999), continuous time analysis followed by discretization (Khalil, 2004;Nešić and Teel, 2004;Postoyan and Nešić, 2012;Wang, Nešić and Postoyan, 2015), and a mixed continuous and discrete time analysis without discretization (Deza, Busvelle, Gauthier and Rakotopora, 1992;Ahmed-Ali and Lamnabhi-Lagarrigue, 2012;Raff, Kögel and Allgöwer, 2008;Van Assche, Ahmed-Ali, Ham and Lamnabhi-Lagarrigue, 2011;Nadri, Hammouri and Grajales, 2013;Karafyllis and Kravaris, 2009;Ahmed-Ali, Van Assche, Massieu and Dorléans, 2013;Zhang, Shen and Xia, 2014). More specifically, two classes of global exponential observers have been presented for a class of continuous systems with sampled and delayed measurements in (Ahmed-Ali, Van Assche, Massieu and Dorléans, 2013).…”