5,369 research outputs found
Value of Information in Feedback Control
In this article, we investigate the impact of information on networked
control systems, and illustrate how to quantify a fundamental property of
stochastic processes that can enrich our understanding about such systems. To
that end, we develop a theoretical framework for the joint design of an event
trigger and a controller in optimal event-triggered control. We cover two
distinct information patterns: perfect information and imperfect information.
In both cases, observations are available at the event trigger instantly, but
are transmitted to the controller sporadically with one-step delay. For each
information pattern, we characterize the optimal triggering policy and optimal
control policy such that the corresponding policy profile represents a Nash
equilibrium. Accordingly, we quantify the value of information
as the variation in the cost-to-go of the system given
an observation at time . Finally, we provide an algorithm for approximation
of the value of information, and synthesize a closed-form suboptimal triggering
policy with a performance guarantee that can readily be implemented
Dynamic Quantized Consensus of General Linear Multi-agent Systems under Denial-of-Service Attacks
In this paper, we study multi-agent consensus problems under
Denial-of-Service (DoS) attacks with data rate constraints. We first consider
the leaderless consensus problem and after that we briefly present the analysis
of leader-follower consensus. The dynamics of the agents take general forms
modeled as homogeneous linear time-invariant systems. In our analysis, we
derive lower bounds on the data rate for the multi-agent systems to achieve
leaderless and leader-follower consensus in the presence of DoS attacks, under
which the issue of overflow of quantizer is prevented. The main contribution of
the paper is the characterization of the trade-off between the tolerable DoS
attack levels for leaderless and leader-follower consensus and the required
data rates for the quantizers during the communication attempts among the
agents. To mitigate the influence of DoS attacks, we employ dynamic
quantization with zooming-in and zooming-out capabilities for avoiding
quantizer saturation
Self-triggered Consensus of Multi-agent Systems with Quantized Relative State Measurements
This paper addresses the consensus problem of first-order continuous-time
multi-agent systems over undirected graphs. Each agent samples relative state
measurements in a self-triggered fashion and transmits the sum of the
measurements to its neighbors. Moreover, we use finite-level dynamic quantizers
and apply the zooming-in technique. The proposed joint design method for
quantization and self-triggered sampling achieves asymptotic consensus, and
inter-event times are strictly positive. Sampling times are determined
explicitly with iterative procedures including the computation of the Lambert
-function. A simulation example is provided to illustrate the effectiveness
of the proposed method.Comment: 29 pages, 3 figures. To appear in IET Control Theory & Application
Resilient Control under Denial-of-Service
We investigate resilient control strategies for linear systems under
Denial-of-Service (DoS) attacks. By DoS attacks we mean interruptions of
communication on measurement (sensor-to-controller) and/or control
(controller-to-actuator) channels carried out by an intelligent adversary. We
characterize the duration of these interruptions under which stability of the
closed-loop system is preserved. The resilient nature of the control descends
from its ability to adapt the sampling rate to the occurrence of the DoS.Comment: 10 pages, abridged version submitte
Simulating Real-Time Aspects of Wireless Sensor Networks
Wireless Sensor Networks (WSNs) technology has been mainly used in the applications with low-frequency sampling and little computational complexity. Recently, new classes of WSN-based applications with different characteristics are being considered, including process control, industrial automation and visual surveillance. Such new applications usually involve relatively heavy computations and also present real-time requirements as bounded end-to- end delay and guaranteed Quality of Service. It becomes then necessary to employ proper resource management policies, not only for communication resources but also jointly for computing resources, in the design and development of such WSN-based applications. In this context, simulation can play a critical role, together with analytical models, for validating a system design against the parameters of Quality of Service demanded for. In this paper, we present RTNS, a publicly available free simulation tool which includes Operating System aspects in wireless distributed applications. RTNS extends the well-known NS-2 simulator with models of the CPU, the Real-Time Operating System and the application tasks, to take into account delays due to the computation in addition to the communication. We demonstrate the benefits of RTNS by presenting our simulation study for a complex WSN-based multi-view vision system for real-time event detection
Data-Driven Control of Distributed Event-Triggered Network Systems
The present paper deals with data-driven event-triggered control of a class
of unknown discrete-time interconnected systems (a.k.a. network systems). To
this end, we start by putting forth a novel distributed event-triggering
transmission strategy based on periodic sampling, under which a model-based
stability criterion for the closed-loop network system is derived, by
leveraging a discrete-time looped-functional approach. Marrying the model-based
criterion with a data-driven system representation recently developed in the
literature, a purely data-driven stability criterion expressed in the form of
linear matrix inequalities (LMIs) is established. Meanwhile, the data-driven
stability criterion suggests a means for co-designing the event-triggering
coefficient matrix and the feedback control gain matrix using only some offline
collected state-input data. Finally, numerical results corroborate the efficacy
of the proposed distributed data-driven ETS in cutting off data transmissions
and the co-design procedure.Comment: 13 pages, 8 figure
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