A distributed reduced-order unknown input observer

Abstract

This paper presents a method of designing distributed observers for linear systems with unknown inputs. Under the requirement of distributed state estimation, outputs of the system are jointly and severally measured by a group of local observer nodes, for the sensing capability of each one is often limited. Therefore, at a local observer, an accurate full state estimation relies on communications with neighbors if the outputs available for use are restricted. In such distributed scenarios, this paper gives conditions for the unknown input decoupling state estimation, under which the designed distributed observer works and has a lower order. For a linear dynamical system of dimension n, the ith local observer is of dimension n−pi if pi-dimensional outputs are available. Each local observer can produce an n-dimensional state estimation with an exponential rate of convergence, free from unknown inputs and more efficient than its full-order counterparts. And beyond that, the design can be done in a robustly completely distributed way.