1,721,015 research outputs found
Advanced control design and fault diagnosis
Full text linkThis document provides the motivations and a brief introduction to the Special Issue entitled “Advanced Control Design and Fault Diagnosis”, which aims at presenting several solutions to the advanced control design and fault diagnosis systems. These methodologies can be considered in the general framework of advanced control, fault diagnosis and fault tolerant control systems, which are also able to improve the safety of the system under monitoring. The focuses of the current research in this field addressed in this Special Issue are also presented with emphasis on the practical application to simulated and realistic examples, which should provide an overall picture of current and future developments in this area. The works of this Special Issue represent suitably extended contributions selected by the proponents from the ACD2019—the 15th European Workshop on Advanced Control and Diagnosis, which was organised in Bologna, Italy on 21st–22nd November
Results in the Structural-Geometric Approach to Switching Linear Systems
No full textIn this survey we present recent results on switching linear systems. In particular, we recall structural-geometric notions of invariance, controlled invariance and conditioned invariance for switching linear systems and we show how they can be used to provide solutions to a number of control and application problems
Disturbance decoupling with stability for impulsive switching linear systems
No full textThis paper deals with the problem of decoupling the output of a hybrid system from a disturbance input by means of a switching state feedback, which, at the same time, stabilizes, in a suitable sense, the compensated system. The class of hybrid systems considered consists of impulsive switching linear systems, that is switching linear systems whose state exhibits impulsive discontinuities, called jumps, at the switching instants. Switching is assumed to be time-driven and the distance between consecutive switching instants is assumed to be lower bounded by some positive number. Structural geometric methods and tools are used to investigate the decoupling problem and to study feedback stabilizability. Necessary and sufficient solvability conditions are given in the case in which the distance between consecutive switching instants can be assumed to be sufficiently large. A sufficient solvability condition is also provided in the case in which the lower bound for such distance is assigned
Unknown-input state observers with minimal order for linear impulsive systems
No full textThis paper deals with the problem of asymptotically estimating a linear function of the state of a linear impulsive system, in the presence of unknown inputs, by means of an observer whose state space has the minimal possible dimension. The linear impulsive systems considered are subject to the following constraint: the length of the time interval between any two consecutive jumps must be greater than or equal to a given finite positive constant. First, a necessary and sufficient condition for the existence of an observer whose state space has a generic dimension (i.e., not necessarily minimal) is proven. Then, the issue of the minimization of the observer state dimension is investigated and solved
A structural approach to unknown inputs observation for switching linear systems
Full text linkThe problem of devising an asymptotic observer for a given function of the state of a switching linear system in the presence of unknown inputs is considered. Solvability is studied both in the case of sufficiently large dwell time and in that of dwell time greater than a fixed threshold. A complete characterization of solvability in terms of necessary and sufficient conditions is given in both cases. It is shown that the necessary and sufficient conditions can be checked in practice in the first case and, under slightly more restrictive hypotheses, also in the second case by means of algorithmic procedures, which also provide a method to synthesize the observer sought for. The employed methodology makes use of geometric concepts to reveal the structural aspects of the problem and to derive its solutions. In particular, a key role is played by the novel notion of robust conditioned invariant subspace that is minimal with respect to the properties of containing a given subspace and of being externally stabilizable
Convolution profiles for right inversion of multi-variable non-minimum phase discrete-time systems
No full textThe problem of the non-causal inversion of linear multivariable discrete-time systems is analyzed in the geometric approach framework and is solved through the computation of convolution profiles which guarantee perfect tracking under the assumption of infinite-length preaction and postaction time intervals. It is shown how the shape of the convolution profiles is related to both the relative degree and the invariant zeros of the plant. A computational setting for the convolution profiles is derived by means of the standard geometric approach tools. Feasibility constraints are also taken into account. A possible implementation scheme, based on a finite impulse response system acting on a stabilized control loop, is provided. © 2002 Elsevier Science Ltd. All rights reserved
Fault Detection Problems for Switching Linear Systems: A Structural Approach
Full text linkThe fault detection and isolation problem is considered in the context of switching linear systems. The problem is tackled by searching for suitable residual signal generators, whose existence is completely characterized in structural terms. Both the situation in which the initial condition of the system subject to possible faults is known and that in which it is not known are considered. The results are compared with those found in the classical linear case for the same problem using a structural geometric approach in order to show consistency and to highlight differences.The fault detection and isolation problem is considered in the context of switching linear systems. The problem is tackled by searching for suitable residual signal generators, whose existence is completely characterized in structural terms. Both the situation in which the initial condition of the system subject to possible faults is known and that in which it is not known are considered. The results are compared with those found in the classical linear case for the same problem using a structural geometric approach in order to show consistency and to highlight differences
A unified algorithmic setting for signal-decoupling compensators and unknown-input observers
No full textA standard geometric-type environment, where only the very basic tools of the geometric approach are used (those supported by well-settled and well-tested computational aids) enables the development of algorithms for numerous control and estimation problems in the discrete-time case. These are: measurable or previewed signal localization problems, perfect or almost perfect tracking (right inversion), and, by duality, perfect or almost perfect unknown input estimation with possible post-knowledge and input reconstruction (left inversion). It is also shown that the devices obtained (compensator and observer), that may be noncausal when specific stability requirements are not met, can be implemented as dynamical systems including finite-horizon convolutors or finite impulse response systems
Geometric insight into discrete-time cheap and singular linear quadratic Riccati (LQR) problems
No full textThe Hamiltonian system related to discrete-time cheap linear quadratic Riccati (LQR) problems is analyzed in a purely geometric context, with the twofold purpose of getting a useful insight into its structural features and deriving a numerically implementable solution for the infinite-horizon case by only using the standard geometric approach routines available
Modeling discrete time systems with variable delays as switching systems without delays
No full textA methodology to model discrete-time systems with variable delays as switching systems is proposed and discussed. In that way, notions and tools developed for switching linear systems, notably the structural approach, can be employed to deal with analysis, control and observation problems for discrete-time linear systems with variable delays. New specific results and a better understanding of the structure of discrete-time linear systems with variable delays arise as outcome
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