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In this note, a new scheme of fault detection (FD) is proposed for linear discrete time-varying (LDTV) systems subject to l2-norm bounded unknown inputs. The basic idea is to find an optimal estimation of the l2-norm of the unknown inputs including the unknown initial state variables. This leads to a natural design of the FD system with the l2-norm boundedness of the unknown inputs as a threshold and the l2-norm of the unknown input estimate as the evaluation function. To avoid heavy computational burden, projection technique in Krein space is applied which allows a recursive computation of the evaluation function. It is shown that the achieved FD system satisfies both the worst case and best case sensitivity/robustness ratio criteria and further applications to observer-based FD lead to an alternative design of H\infty/H\infty and/or H-/H\infty fault detection filter. [ABSTRACT FROM PUBLISHER]

This paper is concerned with the recursive filtering problem for a class of networked linear time-varying systems subject to the scheduling of the random access protocol (RAP). The communication between the sensor nodes and the remote filter is implemented via a shared network. For the purpose of preventing the data from collisions, only one sensor node is allowed to get access to the network at each time instant. The transmission order of sensor nodes is orchestrated by the RAP scheduling, under which the selected nodes obtaining access to the network could be characterized by a sequence of independent and identically-distributed variables. The aim of the addressed filtering problem is to design a recursive filter such that the filtering error covariance could be minimized by properly designing the filter gain at each time instant. The desired filter gain is calculated recursively by solving two Riccati-like difference equations. Furthermore, the boundedness issue of the corresponding filtering error covariance is investigated. Sufficient conditions are obtained to ensure the lower and upper bounds of the filtering error covariance. Two illustrative examples are given to demonstrate the correctness and effectiveness ofour developed recursive filtering approach. [ABSTRACT FROM AUTHOR]

This technical note focuses on a class of switched nonlinear systems with unstable modes and switching uncertainties. Both prescribed switching instants and switching sequence of the nominal switching signal would change. Two novel indexes named time changing ratios and mode changing ratios are proposed, based on which several conditions that fully utilize the trade-off among stable and unstable modes are established to achieve the robust stability of the switched system. An example of multi-agent systems illustrates the efficiency of the new results. [ABSTRACT FROM PUBLISHER]