Recent Advances on Linear Control Theory under Communication Constraints: A Survey (original) (raw)
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Conditions for tracking in networked control systems
2008 47th IEEE Conference on Decision and Control, 2008
In this paper we obtain information theoretical conditions for tracking in linear time-invariant control systems. We consider the particular case where the closed loop contains a channel in the feedback loop. The mutual information rate between the feedback signal and the reference input signal is used to quantify information about the reference signal that is available for feedback. This mutual information rate must be maximized in order to improve the tracking performance. The mutual information is shown to be upper bounded by a quantity that depends on the unstable eigenvalues of the plant and on the channel capacity. If the channel capacity reaches a lower limit, the feedback signal becomes completely uncorrelated with the reference signal, rendering feedback useless. We also find a lower bound on the expected squared tracking error in terms of the entropy of a random reference signal. Examples and simulations are provided to demonstrate the results.
Stabilization of Networked Control Systems via Dynamic Output-Feedback Controllers
Siam Journal on Control and Optimization, 2010
This paper deals with stabilization of networked control systems (NCS) affected by uncertain time-varying delays and data packet dropouts. We point out that such network effects are likely to render the classical control Lyapunov function (CLF) method unfeasible, mainly due to the monotonic decreasing condition. To solve this problem we make use of a discrete-time equivalent of a control Lyapunov-Razumikhin function (CLRF), which is allowed to be non-monotone. The corresponding stabilizing control law is obtained by solving an optimization problem on-line, in a receding horizon manner, which incorporates the available knowledge about the past state/input trajectory. Furthermore, we provide extra flexibility to the CLRF via a relaxation variable, which is needed to handle hard state/input constraints. We also propose an effective method for dealing with delays larger than the sampling period by means of an on-line Minkowski set addition. This makes it possible to guarantee stability even in the presence of data packet dropouts, under certain assumptions.
Stabilisability and detectability in networked control (Regular Papers)
Iet Control Theory and Applications, 2010
We reconsider and advance the analysis of controllability and observability (and the weaker stabilisability and detectability properties) of a class of linear Networked Control Systems (NCSs). We model the NCS as a periodic system with limited communication where the non-updated signals can either be held constant (the zero-order-hold case) or reset to zero. Periodicity is dealt with the lifting technique. We provide conditions for controllability (stabilisability) and observability (detectability) of the NCS given a communication sequence and the controlled plant model. These conditions allow to find communication sequences which are shorter than previously established. A strict lower bound for the sequence length is given. In the sampled-data case, we prove that a communication sequence that avoids particularly defined pathological sampling rates and particular eigenvalues can preserve stabilisability (and detectability for the dual problem) with a 'minimum' sequence length.
2007 46th IEEE Conference on Decision and Control, 2007
We study the problem of distributed stabilization of linear systems over communication channels. Building on our earlier work, we adopt an information theoretic look at the signaling problem when the system and observations are noisy. We provide a lower bound on the average sum-rate, which is tight when the system noise is absent. We further show that when the system and observations are noisy, the signaling process involves coding over an unknown channel with unequal side information between the stations, and as such its construction is fairly complicated. This leads to new insights on designing distributed controllers connected over channels.
Stabilization of Networked Multi-Input Systems With Channel Resource Allocation
IEEE Transactions on Automatic Control, 2000
In this paper, we study the problem of stabilizing a linear time-invariant discretetime system with information constraints in the input channels. The information constraint in each input channel is modelled as a sector uncertainty. Equivalently, the transmission error of an input channel is modelled as an additive system uncertainty with a bound in the induced norm. We attempt to find the least information required, or equivalently the largest allowable uncertainty bound, in each input channel which renders the stabilization possible. The solution for the single-input case, which gives a typical H ∞ optimal control problem, is available in the literature and is given analytically in terms of the Mahler measure or topological entropy of the plant. The main purpose of this paper is to address the multi-input case. In the multi-input case, if the information constraint in each input channel is given a priori, then our stabilization problem turns out to be a so-called µ synthesis problem, a notoriously hard problem. In this paper, we assume that the information constraints in the input channels are determined by the network resources assigned to the channels and they can be allocated subject to a total recourse constraint. With this assumption, the resource allocation becomes part of the design problem and a modified µ synthesis problem arises. Surprisingly, this modified µ-synthesis problem can be solved analytically and the solution is also given in terms of the Mahler measure or topological entropy as in the single-input case.
New Trends in Networked Control of Complex Dynamic Systems: Theories and Applications
Mathematical Problems in Engineering, 2014
In recent years, networked control systems (NCSs) have been extensively studied in both academy and industry and used in many fields, such as telerobotics, smart grids, intelligent transportation systems, and even in medical, military, and aerospace applications. NCSs offer great advantages, such as low cost, high reliability, simple installation and maintenance, and reduced weight and power requirements. In the meantime, the common shortcomings of the communication networks, such as transmission delays, packets drops and disorder, and data quantization, also appeared in the loops of the networked systems. During past decade, plenty of studies have been carried out in the literature to address the networkinduced problems for given dynamic systems that are relatively simple. However, more challenging mathematical problems such as network-based control of more complex dynamics, including time delay, parameter variations, uncertainties, and nonlinearities, are still largely open and necessitate further investigations to enable wider and more successful applications. This special issue aims to provide a timely discussion on the trends and challenges of networked control of complex dynamics systems. Both theoretical and application-oriented papers are sought for, addressing the issues and mathematical techniques of network-based control, sensing, multiagent control of complex dynamic systems, and so forth.
Survey of studies on network-induced constraints in networked control systems
2013
While Networked Control Systems (NCSs) have been bringing innovative impacts to control systems, great challenges due to the network-induced imperfections are posed to the traditional control methodologies. For different scenarios, such network-induced imperfections can be viewed as various constraints which should be appropriately considered in the analysis and design of NCSs. The survey aims to termwise retrospect the studies on the main methodologies coping with several typical network-induced ...
Inherent issues in networked control systems: a survey
2004
Due to major advancements in the area of networking over the past decade, a new paradigm of control systems has emerged, namely networked control systems. Such systems differ from classical control systems in that their control loops are closed around communication networks. Thus, the need for new stability and performance guarantees arises. In this paper, we aim to shed some
A Survey of Recent Results in Networked Control Systems
Proceedings of The IEEE, 2007
Networked Control Systems (NCSs) are spatially distributed systems for which the communication between sensors, actuators, and controllers is supported by a shared communication network. In this paper we review several recent results on estimation, analysis, and controller synthesis for NCSs. The results surveyed address channel limitations in terms of packet-rates, sampling, network delay and packet dropouts. The results are presented in a tutorial fashion, comparing alternative methodologies.