IET Control Theory & Applications

This study focuses on the problem of regional stability analysis of rational control systems with saturating actuators. Estimates of the region of attraction are computed by means of invariant domains associated to rational Lyapunov functions. Conditions for computing these invariant domains (regions of stability) are proposed in the form of linear matrix inequalities (LMIs). These conditions are ... View full abstract»

Permanent magnet linear synchronous motors (PMLSMs) are a type of linear synchronous motors that are widely used in motor control applications. However, in PMLSMs, the accuracy of position control is easily affected by variations in its parameters and load disturbances. In this study, the implementation of a direct thrust control (DTC) method by using a modified integrator for flux estimation is p... View full abstract»

In this study, the moving horizon recursive state estimator for linear singular systems is derived from the least squares estimation problem. It will be shown that this procedure yields the same state estimate as the Kalman filter for descriptor systems when the noises are Gaussian. The obtained results are applied to the state and the unknown inputs estimation for discrete-time systems with unkno... View full abstract»

For power systems with detailed excitation and power system stabiliser (PSS) controller, the authors set up a singular perturbation dynamical model with saturation non-linearities for their small-signal stability analysis. To estimate the stability region of this kind of dynamical systems, they establish a set of conditions under which the stability region can be decomposed into the Cartesian prod... View full abstract»

This study presents H2 and H∞ performance analysis and synthesis procedures for the design of both gain-scheduled and robust static output feedback controllers for discrete-time linear systems with time-varying parameters. The obtained controllers guarantee an upper bound on the H2 or H∞ performance of the closed-loop system. As an immedi... View full abstract»

This study investigates the problem of H ∞ static output feedback (SOF) control for discrete-time switched linear systems with average dwell time. By the aid of multiple Lyapunov functions combined with Finsler's lemma, a switched SOF controller is designed such that the closed-loop switched system is exponentially stable and achieves a weighted L 2-gain... View full abstract»

Covariance control theory provides a parameterisation of all controllers which assign a specified state covariance matrix to the closed-loop system according to different requirements on system performance. In this study, an innovative scheme for covariance system description based on the original linear stochastic system is proposed. The main idea of the proposed scheme is based on a special rear... View full abstract»

As a highly undesirable situation, deadlocks usually occur in flexible manufacturing systems because of the limited resources. To develop a deadlock control policy, Petri nets (PN) are widely used to model these systems. For a class of PN, WS3PR-weighted systems of simple sequential processes with resources, this study reveals the relationship between its siphons and deadlocks and explo... View full abstract»

A relatively simple approach to non-linear predictive generalised minimum variance (NPGMV) control is introduced for non-linear discrete-time multivariable systems. The system is represented by a combination of a stable non-linear subsystem where no structure is assumed and a linear subsystem that may be unstable and modelled in polynomial matrix form. The multi-step predictive control cost index ... View full abstract»

Over the past 15 years, a number of model-based proportional-integral-derivative (PID) tuning methods have been developed for systems that can be described as integrating-with-deadtime. This was motivated by the observation that the initial open-loop response of lag-dominant processes, such as tray temperature in high-purity distillation columns, resembles that of a delayed ramp variable. This stu... View full abstract»

In this study, a novel non-linear stochastic adaptive sliding-mode observer is extended to reconstruct the states of a non-linear stochastic system with model uncertainties. Also, both process and measurement noises are considered in the system model. The outstanding feature of the proposed observer is its stability in probability which is proved through a theorem based on stochastic Lyapunov stab... View full abstract»

In this study, a modified design of the internal model control (IMC) filter is proposed for improving closed-loop system performance of load disturbance rejection, especially for slow processes in industrial and chemical engineering practices. The deficiency of a conventional IMC filter design for controller tuning is revealed with regard to load disturbance rejection. By constructing one or more ... View full abstract»

A fundamental and required property of congestion control algorithms in computer networks is stability. In this study, a class of appropriate Lyapunov functionals is proposed to investigate asymptotic stability in the second-order congestion control systems with heterogeneous communication delays. Novel linear matrix inequality-based delay-dependent stability criteria are given by exploiting free ... View full abstract»

This study deals with the design of a guidance scheme based on flatness theory and dedicated to the terminal area energy management phase of a reusable launch vehicle. The proposed guidance strategy is based on a non-linear dynamic inversion technique to handle the large flight envelope that characterises the reentry mission. This inversion takes advantage of a particular choice of linearising ter... View full abstract»

This study is concerned with consensus problems for a class of multi-agent systems with second-order dynamics. Some dynamic neighbour-based rules are adopted for the agents with the consideration of parameter uncertainties and external disturbances. Sufficient conditions are derived to make all agents asymptotically reach consensus while satisfying desired H ∞ performance... View full abstract»

This article studies the H ∞ model reduction problem for linear continuous-time systems over a finite-frequency interval. Different from the existing methods in the literature, we resort to the aid of recently developed generalised Kalman-Yakubovich-Popov (GKYP) lemma. Based on a in-depth exploitation of the GKYP lemma and the Projection lemma, sufficient conditions for t... View full abstract»

In this study, the problem of designing regular robust l2-l∞ filter for a class of linear singular discrete-time systems with norm-bounded uncertainties is investigated. A class of regular linear filters is fully analysed, then necessary and sufficient conditions of robust admissibility are established. Guaranteed l2-l∞ performance of the... View full abstract»