State Regulation and State Observation in Networked Control Systems (original) (raw)
Related papers
New results on networked control systems with non-stationary packet dropouts
In this study, an improved observer-based stabilising controller has been designed for networked systems involving both random measurement and actuation delays and subject to non-stationary packet dropouts. The developed control algorithm is suitable for networked systems with any type of delays. By the simultaneous presence of binary random delays and making full use of the delay information in the measurement model and controller design, new and less conservative stabilisation conditions for networked control systems are derived. The criterion is formulated in terms of linear matrix inequalities. Detailed simulation studies on representative systems are provided to show the applicability of the developed design technique.
Delays and packet losses are undesirable from a control system perspective as they tend to adversely affect performance. Networked Control Systems (NCSs) are a class of control systems wherein control components exchange information using a shared communication channel. Delays and packet losses in the communication channels are usually random, thereby making the analysis and design of control loops more complex. The usual assumptions in classical control theory, such as delay free sensing and synchronous actuation, assume lesser significance when it comes to NCSs. Hence, this necessitates a reformulation / relook into the existing models used for NCS control loop analysis and design. In this paper, we study and present the reformulations required for NCSs to include random delays and packet losses in the channel. This paper therefore, provides a unified baseline and framework for analyzing a host of problems that can be captured as NCSs subjected to random delays and packet losses.
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
2011
In this work, the design of an observer for systems whose output measurements are acquired through a network is addressed. The measurements are assumed to scarcely available, and arriving randomly on time. The noises of the measurement devices are assumed to be known, but the system disturbances are not. A new parameter that can be calculated on line and that measures the relationship between noise measurement and the output estimation error is defined. This parameter is related to the unknown disturbance and, hence, an observer depending on that parameter is defined. A parametric optimization problem is stated for the observer design, leading to an stable observer that minimizes the effect of both the noise and the unknown disturbance. The proposed approach is compared with the Kalman filter approach under the assumption of known and unknown disturbances, showing the validity of the approach.
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.
Stochastic stability analysis of packet-based networked control systems
Proceedings of the 48h IEEE Conference on Decision and Control (CDC) held jointly with 2009 28th Chinese Control Conference, 2009
By taking advantage of the packet-based transmission in networked control systems (NCSs), a packet-based control approach is proposed for NCSs. Using this approach, the control law can be designed with explicit compensation for networkinduced delay, data packet dropout and data packet disorder simultaneously. The sufficient and necessary condition for the stochastic stability of the closed-loop system is obtained, by modeling the closed-loop system as a Markov jump system. A numerical example is also considered to illustrate the effectiveness of the proposed approach.
Introduccion. Networked Control Systems (NCS) are systems in which serial communication networks are used to exchange system information and control signals between various physical components of the systems that may be physically distributed. Major advantages of NCS include low cost, reduced weight and power requirements, simple installation and maintenance, and high reliability. Nonetheless, closing a control loop on a shared communication network introduces additional dynamics and constraints in the control problem. In addition to being bit-rate limited [1], [2], practical communitacion channels are commonly affected by packet dropouts and time delays, mainly due to transmission errors and waiting times to access the medium; see, e.g., [3]-[5] and the many references therein.
Stability of networked control systems: analysis of packet dropping
ICARCV 2004 8th Control, Automation, Robotics and Vision Conference, 2004.
In this paper, we analyze the stability of a Networked Control System with random delay. We consider a first order continuous process that is sampled at constant intervals, a discrete controller and a control delay less than one sampling period. Analytical expressions are obtained for the probability density function (pdf) of the eigenvalues of the closed loop system. Our objective is to determine the probability of the system become unstable for given design parameters and for a given pdf model for the control delay.
Practical issues in networked control systems
2006 American Control Conference, 2006
In this paper we expose experimental issues faced in a closed-loop networked control system. We also propose some compensation actions, and evaluate their performance for different experimental setups, focusing specifically on time delays.
A non-uniform predictor-observer for a networked control system
2011
This paper presents a Non-Uniform Predictor-Observer (NUPO) based control approach in order to deal with two of the main problems related to Networked Control Systems (NCS) or Sensor Networks (SN): time-varying delays and packet loss. In addition, if these delays are longer than the sampling period, the packet disordering phenomenon can appear. Due to these issues, a (scarce) non-uniform, * Corresponding author 1 delayed measurement signal could be received by the controller. But including the NUPO proposal in the control system, the delay will be compensated by the prediction stage, and the non-available data will be reconstructed by the observer stage.