Observer design for networked control systems implemented over WirelessHART

Abstract

We study the design of state observers for nonlinear networked control systems (NCSs) that are implemented over WirelessHART (WH). WH is a wireless communication protocol for process automation applications. It is characterised by its multi-hop structure, slotted communication cycles, and simultaneous transmission over different frequencies. We present a solution based on the emulation approach. That is, given an observer designed with a specific stability property in the absence of communication constraints, we implement it over a WH network and we provide sufficient conditions on the latter, to preserve the stability property of the observer. In particular, we provide explicit bounds on the maximum allowable transmission interval. We assume that the plant dynamics and measurements are affected by noise and we guarantee an inputto-state stability property for the corresponding estimation error system.

Observer Design for Nonlinear Networked Control Systems With Persistently Exciting Protocols

“…In this current work, and inspired by [10], we use similar techniques in the context of observer design to show that exploitation of WH network structure yields less conservative MATI bounds guaranteeing an ISS property for the estimation error system. Moreover, we improve our previous results in [13], where we used UGES protocols and Lyapunov-based analysis in the observer design problem over WH-NCSs. Finally, we illustrate our results in the design of high gain observers for a class of Lipschitz non-linear systems.…”

“…Such structure is exploited in our analysis to further reduce conservatism, yielding an even larger MATI bound. Moreover, we illustrate in examples that this bound is significantly larger than the bound proposed in [13].…”

“…be found in the literature [6], [13], denoted by τ * [6] and τ * [13] respectively. With all the above, Table II 2 , γ ς 1 , A and T that we computed in Section VII-A for our case study.…”

“…Further below, we simulate the response of the NCS for which external disturbances and noise are reflected in the estimation error. The following comments can be made from Table II. 1) Our recent work [13] was a first attempt to obtaining MATI bounds tailored to observer design in WH-NCSs. This bound τ * [13] is quite conservative in the context of WH, as we discuss further below.…”

“…The following comments can be made from Table II. 1) Our recent work [13] was a first attempt to obtaining MATI bounds tailored to observer design in WH-NCSs. This bound τ * [13] is quite conservative in the context of WH, as we discuss further below. 2) As shown in [10], assuming a P E T condition on the protocols allows for less conservative MATI bounds in the context of controller design.…”