Stabilization of systems with asynchronous sensors and controllers

We study the stabilization of networked control systems with asynchronous sensors and controllers. Offsets between the sensor and controller clocks are unknown and modeled as parametric uncertainty. First we consider multi-input linear systems and provide a sufficient condition for the existence of linear time-invariant controllers that are capable of stabilizing the closed-loop system for every clock offset in a given range of admissible values. For first-order systems, we next obtain the maximum length of the offset range for which the system can be stabilized by a single controller. Finally, this bound is compared with the offset bounds that would be allowed if we restricted our attention to static output feedback controllers.Comment: 32 pages, 6 figures. This paper was partially presented at the 2015 American Control Conference, July 1-3, 2015, the US

A review on analysis and synthesis of nonlinear stochastic systems with randomly occurring incomplete information

Copyright q 2012 Hongli Dong et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.In the context of systems and control, incomplete information refers to a dynamical system in which knowledge about the system states is limited due to the difficulties in modeling complexity in a quantitative way. The well-known types of incomplete information include parameter uncertainties and norm-bounded nonlinearities. Recently, in response to the development of network technologies, the phenomenon of randomly occurring incomplete information has become more and more prevalent. Such a phenomenon typically appears in a networked environment. Examples include, but are not limited to, randomly occurring uncertainties, randomly occurring nonlinearities, randomly occurring saturation, randomly missing measurements and randomly occurring quantization. Randomly occurring incomplete information, if not properly handled, would seriously deteriorate the performance of a control system. In this paper, we aim to survey some recent advances on the analysis and synthesis problems for nonlinear stochastic systems with randomly occurring incomplete information. The developments of the filtering, control and fault detection problems are systematically reviewed. Latest results on analysis and synthesis of nonlinear stochastic systems are discussed in great detail. In addition, various distributed filtering technologies over sensor networks are highlighted. Finally, some concluding remarks are given and some possible future research directions are pointed out. © 2012 Hongli Dong et al.This work was supported in part by the National Natural Science Foundation of China under Grants 61273156, 61134009, 61273201, 61021002, and 61004067, the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grant GR/S27658/01, the Royal Society of the UK, the National Science Foundation of the USA under Grant No. HRD-1137732, and the Alexander von Humboldt Foundation of German

Robust stabilization of a class of nonlinear systems controlled over communication networks

The paper deals with the stabilization of nonlin-ear systems in which the loop is closed over a lossy non-acknowledged communication network. Given a Regional Input-to-State (ISS) stabilizing state-feedback control law, designedwithout accounting for the network-induced delays, we proposea non-acknowledged communication policy that allows to deploythe above controller over the network without any modification,while preserving the Regional ISS property. The time-varyingdelays and packet dropouts occurring on both the up-link andthe down-link are compensated through a model-based predictionscheme and a packet-management policy based on time-stamping.The consistency of the prediction, which is a major issue inthe context of nonlinear systems with an embedded networkedcontroller, is guaranteed through the exploitation of a novel move-blocking strategy for computing the command sequence to beforwarded to the actuators

A review of convex approaches for control, observation and safety of linear parameter varying and Takagi-Sugeno systems

This paper provides a review about the concept of convex systems based on Takagi-Sugeno, linear parameter varying (LPV) and quasi-LPV modeling. These paradigms are capable of hiding the nonlinearities by means of an equivalent description which uses a set of linear models interpolated by appropriately defined weighing functions. Convex systems have become very popular since they allow applying extended linear techniques based on linear matrix inequalities (LMIs) to complex nonlinear systems. This survey aims at providing the reader with a significant overview of the existing LMI-based techniques for convex systems in the fields of control, observation and safety. Firstly, a detailed review of stability, feedback, tracking and model predictive control (MPC) convex controllers is considered. Secondly, the problem of state estimation is addressed through the design of proportional, proportional-integral, unknown input and descriptor observers. Finally, safety of convex systems is discussed by describing popular techniques for fault diagnosis and fault tolerant control (FTC).Peer ReviewedPostprint (published version

Switching LPV Approach for Analysis and Control of TCP-based Cyber-Physical Systems under DoS Attack

Cyberphysical systems (CPSs) integrate controllers, sensors, actuators, and communication networks. Tight integration with communication networks makes CPSs vulnerable to cyberattacks. In this paper, we investigate the impact of denial of service (DoS) attack on the stability of cyber physical systems by considering the transmission control protocol (TCP) and extract a sufficient stability condition in linear matrix inequality (LMI) form. To this end, we model the TCP-CPS under DoS attack as a switching LPV time delay system by using the Markov jump model. Then, we design parameter dependent stabilizing controller for CPS under DoS attack, by considering the network parameters

Stability Analysis of Uncertain Temperature control system with two additive delays and nonlinear perturbation

In this paper, the problem of robust delay-dependent stability criterion is considered for a class of linear continuous time heat exchanger system with constant additive state-delays and bounded nonlinear perturbations using Lyapunov-Krasovskii (LK) functional approach.  In the proposed delay-dependent stability analysis, the time-delays are considered to be time-invariant.  In the proposed delay-dependent stability analysis, a candidate LK functional is considered, and take the time-derivative of the functional is bounded using the Jenson integral inequality.  The proposed stability analysis finally culminates into a stability criterion in LMI framework.  The effectiveness of the proposed stability criterion is illustrated using a network controlled temperature control of heat exchanger syste