1,721,069 research outputs found
Algres: un linguaggio relazionale esteso per la prototipizzazione di applicazioni complesse
No full textLTV stochastic systems stabilization with large and variable input delay
Full text linkIn this paper we propose a solution to the state-feedback and output-feedback stabilization problem for linear time-varying stochastic systems affected by arbitrarily large and variable input delay. It is proved that under the proposed controller the underlying stochastic process is exponentially centered and mean square bounded. The solution is given through a set of delay differential equations with cardinality proportional to the delay bound. The predictor is based on the semigroup generated by the closed-loop system in absence of delay, and its computation is described by a numerically reliable and robust method. In the deterministic case this method generates the same optimal trajectories as in the delay-less case
Stable Internally Positive Representations of Continuous Time Systems
No full textAn Internally Positive Representation (IPR) of a non-positive system is a positive system that, under suitable input, state and output transformations, exactly replicates the behavior of the original system.
Any construction method of an IPR necessarily introduces additional natural modes, which in some cases are unstable.
In a previous paper the authors have presented a method that provides a stable IPR % of continuous-time systems if and only if the eigenvalues of the original system % matrix (or the poles of the transfer matrix) belong to lie in a specific sector of the open left-half complex plane.
In this paper a new technique is proposed that overcomes such a limitation, and provides a stable IPR for any stable system, although in some cases the dimension of the IPR must be large in order to guarantee its stability.
Although, for simplicity, the method is only illustrated for single-input single-output systems with distinct eigenvalues, it also applies to multi-input multi-output systems with multiple eigenvalues
Distributed Infinite-Horizon Optimal Control of Discrete-Time Linear Systems over Networks
Full text linkIn this paper we consider the distributed infinite-horizon Linear-Quadratic-Gaussian optimal control problem for discrete-time systems over networks. In particular, the feedback controller is composed of local control stations, which receives some measurement data from the plant process and regulates a portion of the input signal. We provide a solution when the nodes have information on the structural data of the whole network but takes local actions, and also when only local information on the network are available to the nodes. The proposed solution is arbitrarily close to the optimal centralized one (in terms of cost index) when the intermediate consensus steps are sufficiently large
Stochastic predictor-based leader-following control with input and communication delays
Full text linkWe consider the leader-following control problem on connected directed graphs for stochastic linear agents in the presence of communications and actuator delays. We propose to use a distributed protocol for detecting the distance of agents from the leader and we show that by suitably using this information it is possible to solve efficiently the leader-following control problem by means of predictors, thus recovering results for the single-agent case. The proposed predictor and controller are easy to design and the delay bound that guarantees stability can be computed from closed-form expressions without resorting to LMIs
The observer follower filter: A new approach to nonlinear suboptimal filtering
No full textThis paper investigates the state estimation problem for a class of stochastic nonlinear differential
systems. A novel algorithm is proposed, denoted as Observer Follower Filter (OFF), based on a two-steps,
mixed approach: the first step makes use of a high-gain observer-based estimator for nonlinear systems,
applied to the system equations in order to provide the trajectory around which a ν-degree Carleman
approximation of the stochastic differential system is achieved, second step. In principle, any other highgain
estimator can be used, but in this note we prove that the one here proposed provides a bounded
mean square error. Numerical simulations show the effectiveness of the proposed methodology, and the
improvements of the OFF with respect to the standard Extended Kalman–Bucy Filter (EKBF) obtained by
increasing the order of the Carleman approximatio
Exponential stabilization of linear systems with time-varying delayed state feedback via partial spectrum assignment
No full textWe consider the problem of controlling a linear system when the state is available with a known time-varying delay (delayed-state feedback control) or the actuator is affected by a delay. The solution proposed in this paper consists in partially assigning the spectrum of the closed-loop system to guarantee the exponential zero-state stability with a prescribed decay rate by means of a finite-dimensional control law. A non conservative bound on the maximum allowed delay for the prescribed decay rate is presented, which holds for both cases of constant and time-varying delays. An advantage over recent and similar approaches is that differentiability or continuity of the delay function is not required. We compare the performance of our approach, in terms of delay bound and input signal, with another recent approach
An Enhanced Observer for Nonlinear Systems with Time-Varying Measurement Delays
No full textIn this article, we propose an observer for a class of Lipschitz nonlinear systems affected by time-varying and known measurement delays, which is an improvement of the one presented by Cacace et al., 2014. Under the assumption that the delay function is piecewise continuous and differentiable, we prove that exponential convergence to zero of the observation error can be achieved with any desired decay rate, by suitably tuning a gain vector. The delay bound achieved with the observer proposed here is less conservative than the one obtained by Cacace et al., 2014, as confirmed by numerical tests. For the sake of brevity, in this article, only one-step observers are considered. However, a cascade observer can be arranged to cope with arbitrarily long delays
A new approach to design interval observers for linear systems
No full textInterval observers are dynamic systems that provide upper and lower bounds of the true state trajectories of systems. In this work we introduce a technique to design interval observers for linear systems affected by state and measurement disturbances, based on the
Internal Positive Representations (IPRs) of systems, that exploits the order preserving property of positive systems. The method can be applied to both continuous and discrete time systems
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