Optimal communication logics in networked control systems (original) (raw)

Optimal controller design for networked control systems

… of the 17th IFAC world congress, 2008

This paper addresses the problem of optimal control system design for networked control systems. We focus on a situation where the plant is single-input single-output and the communication link between the controller and the plant is signal-to-noise ratio constrained. In this setting, we characterize the controllers that minimize the tracking error variance, while respecting the channel signal-to-noise ratio constraint. We also provide a description of the optimal tradeoff curve in the performance versus signal-to-noise ratio plane and, as a byproduct, we establish easily computable bounds on the achievable performance. We illustrate our results with a numerical example based on a bit rate limited channel.

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.

Fundamental Issues in Networked Control Systems

This paper provides a survey on modeling and theories of networked control systems (NCS). In the first part, modeling of the different types of imperfections that affect NCS is discussed. These imperfections are quantization errors, packet dropouts, variable sampling/transmission intervals, variable transmission delays, and communication constraints. Then follows in the second part a presentation of several theories that have been applied for controlling networked systems. These theories include: input delay system approach, Markovian system approach, switched system approach, stochastic system approach, impulsive system approach, and predictive control approach. In the last part, some advanced issues in NCS including decentralized and distributed NCS, cloud control system, and co-design of NCS are reviewed.

Communication logics for networked control systems

2004

This paper addresses the control of spatially distributed processes. We utilize a distributed architecture in which multiple local controllers coordinate their efforts through a data network that allows information exchange. We focus our work on linear time invariant processes disturbed by Gaussian white noise and propose several logics to determine when the local controllers should communicate. We provide conditions under which these logics guarantee boundedness and investigate the trade-off between the amount of information exchanged and the performance achieved. The resulting closed-loop systems evolve according to stochastic differential equations with resets triggered by stochastic counters. This type of stochastic hybrid system seems to be interesting on its own. The theoretical results are validated through Monte Carlo simulations.

Networked control systems with packet delays and losses

Conference on Decision and Control, 2008

We investigate the effect of packet delays and packet drops on networked control systems. First we consider the problem of where to locate a controller or state estimator in a network, and show that under a Long Packets Assumption (LPA) it is optimal to collocate it with the actuator. We then show that under the LPA, stabilizability is only determined

Data Transmission Over Networks for Estimation and Control

IEEE Transactions on Automatic Control, 2000

We consider the problem of controlling a linear time invariant process when the controller is located at a location remote from where the sensor measurements are being generated. The communication from the sensor to the estimator is supported by a communication network with arbitrary topology composed of channels that stochastically drop packets. Using a separation principle, we prove that the optimal LQG controller consists of an LQ optimal regulator along with an estimator that estimates the state of the process across the communication network mentioned above.

Optimal control design for the stabilization of network controlled systems

2006

In this paper, the problem of remote output stabilization of networked control systems is investigated. The network is considered as a time-varying delay in the communication channel. An average model of the delay dynamics is supposed to be known and the unpredicted events occurring on the network are introduced as a random input in these dynamics. We propose a constructive control scheme where the deterministic aspect of the network is explicitly taken into account in a predictor-based feedback law. A stochastic descent algorithm is then introduced to set the controller gain according to the non-deterministic part of the delay dynamics. Some simulation results are also presented.

An Effective and Active Bandwidth Distribution in Networked Control Systems

International journal of engineering and advanced technology, 2020

Networked Control System (NCS) is a method composed of physically shared smart devices that can observe the surroundings, work on it, and converse with one another by means of a communication system to attain a widespread purpose. Characteristic examples that fall into this section are Wireless Sensors and Actuators Networks (WSANs) for ecological analyzing and checking, multi-vehicle systems for composed investigation, camera systems for observation, multicamera facilitated movement catch, shrewd lattices for vitality circulation and the executives, and so forth. NCSs changes from increasingly customary control systems as a result of their interdisciplinary which needs the combination of control hypothesis, correspondences, software engineering and programming designing. Plenty of communication modes are available from telephone lines, cell phone networks, satellite networks and most widely used is internet. The choice of network depends upon the application to be served. Internet is the most suitable and inexpensive choice for many applications where the plant and the controller are far from each other. The troubles present in the structure of control systems that are solid to correspondence parameters like transfer speed, arbitrary deferral and packet loss, to computational parameters in light of the tremendous amount of information to be handled or to the mutual idea of the detecting and control to ongoing execution on limited resources and due to the unpredictability to the huge number of untrustworthy agent present. With the limited measure of data transmission accessible, it is improved to use it ideally and proficiently. This further raises the requirement for need choices issue for controlling a series of actuators for a progression of tasks. The proposed methodology deals broadly made in two distinct directions. The first direction aims at a control theoretical analysis while considering the network as a constant parameter like special controllers and altering the sampling rate. The second direction aims the design of new communication network infrastructures, algorithms or protocols like designing static and dynamic message scheduling algorithms. This method combines both directions and depends on the well-recognized results in both communication networks and control theory.

Control methodologies in networked control systems

Control Engineering Practice, 2003

The use of a data network in a control loop has gained increasing attentions in recent years due to its cost effective and flexible applications. One of the major challenges in this so-called networked control system (NCS) is the network-induced delay effect in the control loop. Network delays degrade the NCS control performance and destabilize the system. A significant emphasis has been on developing control methodologies to handle the network delay effect in NCS. This survey paper presents recent NCS control methodologies. The overview on NCS structures and description of network delays including characteristics and effects are also covered.

Inferential networked control with variable accessibility constraints

2009

In this work, an inferential scheme for networked control systems is addressed. An LTI plant with disturbances and measurement noise is assumed to be controlled by a controller that communicates with the sensor and the actuator through a network. This network is assumed to have variable accessibility constraints due to a shared use of it, network-induced delay and packet dropout. In this work a control algorithm is proposed such that the available (and scarce) outputs that arrive delayed on time from its sampling instant are used to make a prediction of the system evolution. That prediction is then used to calculate the control actions that should be applied in the actuator. The algorithm takes into account the possibility of control action drop due to network constraints in order to calculate the control action. This networked control scheme is analyzed in depth and the separation principle between predictor and controller is demonstrated. Both the predictor and controller designs are addressed taking into account the disturbances, the noise measurement, the scarce availability of process output samples and the scarce capability to update the control actions due to the network constraints. Both designs are based on the probability of network availability to transmit the measurements and the input desirable updates on time. The time-varying sampling periods for the input and output of the plant due to the network constraints have been specified and bounded as a function of the probability of success on transmitting the output samples and input updates on a specified time. For both designs H¿ performance has been established and LMI design techniques have been used to achieve a numerical solution.