HKU Scholars Hubhttp://hub.hku.hkThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Tue, 02 Mar 2021 14:47:43 GMT2021-03-02T14:47:43Z506321- H<font size=-1><sub>∞</sub></font> control with transients for singular systemshttp://hdl.handle.net/10722/229239Title: H<font size=-1><sub>∞</sub></font> control with transients for singular systems
Authors: FENG, Z; Lam, J; Xu, S; Zhou, S
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10722/2292392016-01-01T00:00:00Z
- Containment control of multi-agent systems with unbounded communication delayshttp://hdl.handle.net/10722/245064Title: Containment control of multi-agent systems with unbounded communication delays
Authors: SHEN, J; Lam, J
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10722/2450642016-01-01T00:00:00Z
- A novel observer design for simultaneous estimation of vehicle steering angle and sideslip anglehttp://hdl.handle.net/10722/245065Title: A novel observer design for simultaneous estimation of vehicle steering angle and sideslip angle
Authors: Zhang, B; Du, H; Lam, J; Zhang, N; Li, W
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10722/2450652016-01-01T00:00:00Z
- Dominant pole and eigenstructure assignment for positive systems with state feedbackhttp://hdl.handle.net/10722/245068Title: Dominant pole and eigenstructure assignment for positive systems with state feedback
Authors: LI, Z; Lam, J
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10722/2450682016-01-01T00:00:00Z
- An improved incremental learning approach for KPI prognosis of dynamic fuel cell systemhttp://hdl.handle.net/10722/245077Title: An improved incremental learning approach for KPI prognosis of dynamic fuel cell system
Authors: Yin, S; XIE, X; Lam, J; Cheung, KC; Gao, H
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10722/2450772016-01-01T00:00:00Z
- Input-output gain analysis for linear systems on coneshttp://hdl.handle.net/10722/245082Title: Input-output gain analysis for linear systems on cones
Authors: SHEN, J; Lam, J
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10722/2450822017-01-01T00:00:00Z
- On the synthesis of linear H ∞ filters for polynomial systemshttp://hdl.handle.net/10722/157157Title: On the synthesis of linear H ∞ filters for polynomial systems
Authors: Li, P; Lam, J; Chesi, G
Abstract: This paper is concerned with the H ∞ filtering problem for polynomial systems. By means of Lyapunov theory and matrix inequality techniques, sufficient conditions are first obtained to ensure that the filtering error system is asymptotically stable and satisfies H ∞ performance constraint. Then, a sufficient condition for the existence of desired filters is established with a free matrix introduced, which will greatly facilitate the design of filter matrices. By virtue of sum-of-squares (SOS) approaches, a convergent iterative algorithm is developed to tackle the polynomial H ∞ filtering problem. Note that the approach can be efficiently implemented by means of recently developed SOS decomposition techniques, and the filter matrices can be designed explicitly. Finally, a numerical example is given to illustrate the main results of this paper. © 2011 Elsevier B.V. All rights reserved.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/10722/1571572012-01-01T00:00:00Z
- Positive observers and dynamic output-feedback controllers for interval positive linear systemshttp://hdl.handle.net/10722/59118Title: Positive observers and dynamic output-feedback controllers for interval positive linear systems
Authors: Shu, Z; Lam, J; Gao, H; Du, B; Wu, L
Abstract: This paper is concerned with the design of observers and dynamic output-feedback controllers for positive linear systems with interval uncertainties. The continuous-time case and the discrete-time case are both treated in a unified linear matrix inequality (LMI) framework. Necessary and sufficient conditions for the existence of positive observers with general structure are established, and the desired observer matrices can be constructed easily through the solutions of LMIs. An optimization algorithm to the error dynamics is also given. Furthermore, the problem of positive stabilization by dynamic output-feedback controllers is investigated. It is revealed that an unstable positive system cannot be positively stabilized by a certain dynamic output-feedback controller without taking the positivity of the error signals into account. When the positivity of the error signals is considered, an LMI-based synthesis approach is provided to design the stabilizing controllers. Unlike other conditions which may require structural decomposition of positive matrices, all proposed conditions in this paper are expressed in terms of the system matrices, and can be verified easily by effective algorithms. Two illustrative examples are provided to show the effectiveness and applicability of the theoretical results. © 2008 IEEE.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10722/591182008-01-01T00:00:00Z
- Robust D-stability analysis for uncertain discrete singular systems with state delayhttp://hdl.handle.net/10722/43044Title: Robust D-stability analysis for uncertain discrete singular systems with state delay
Authors: Xu, S; Lam, J; Zhang, L
Abstract: This brief investigates the problem of robust D-stability analysis for uncertain discrete singular systems with state delay and structured uncertainties. Sufficient conditions are developed to ensure that, when the nominal discrete singular delay system is regular, causal and all its finite poles are located within a specified disk, the uncertain system still preserves all these properties when structured uncertainties are added into the nominal system. A computationally simple approach is proposed and a numerical example is given to demonstrate the application of the proposed method.
Tue, 01 Jan 2002 00:00:00 GMThttp://hdl.handle.net/10722/430442002-01-01T00:00:00Z
- On positive realness of descriptor systemshttp://hdl.handle.net/10722/44945Title: On positive realness of descriptor systems
Authors: Zhang, L; Lam, J; Xu, S
Abstract: In this brief, the positive realness of descriptor systems is studied. For the continuous-time case, two positive real lemmas are given, based on a generalized algebraic Riccati equation and inequality respectively. For the discrete-time case, the positive real lemma is given in terms of a generalized algebraic Riccati inequality.
Tue, 01 Jan 2002 00:00:00 GMThttp://hdl.handle.net/10722/449452002-01-01T00:00:00Z
- Decentralized H ∞-controller design for nonlinear systemshttp://hdl.handle.net/10722/43026Title: Decentralized H ∞-controller design for nonlinear systems
Authors: Yang, GH; Wang, J; Soh, CB; Lam, J
Abstract: This paper considers the decentralized H ∞-controller design problem for nonlinear systems. Sufficient conditions for the solution of the problem are presented in terms of solutions of Hamilton-Jacobi inequalities. The resulting design guarantees local asymptotic stability and ensures a predetermined L 2-gain bound on the closed-loop system.
Fri, 01 Jan 1999 00:00:00 GMThttp://hdl.handle.net/10722/430261999-01-01T00:00:00Z
- Global point dissipativity of neural networks with mixed time-varying delayshttp://hdl.handle.net/10722/44941Title: Global point dissipativity of neural networks with mixed time-varying delays
Authors: Cao, J; Yuan, K; Ho, DWC; Lam, J
Abstract: By employing the Lyapunov method and some inequality techniques, the global point dissipativity is studied for neural networks with both discrete time-varying delays and distributed time-varying delays. Simple sufficient conditions are given for checking the global point dissipativity of neural networks with mixed time-varying delays. The proposed linear matrix inequality approach is computationally efficient as it can be solved numerically using standard commercial software. Illustrated examples are given to show the usefulness of the results in comparison with some existing results. © 2006 American Institute of Physics.
Sun, 01 Jan 2006 00:00:00 GMThttp://hdl.handle.net/10722/449412006-01-01T00:00:00Z
- LMI synthesis of H2 and mixed H2/H∞ controllers for singular systemshttp://hdl.handle.net/10722/43062Title: LMI synthesis of H2 and mixed H2/H∞ controllers for singular systems
Authors: Zhang, L; Huang, B; Lam, J
Abstract: This paper considers the H2 control problems for continuous-time singular systems with and without an H∞ constraint. Without the constraint, we derive necessary and sufficient conditions for the existence of H2 output feedback controllers using the linear matrix inequality (LMI) approach. With the H∞ constraint, sufficient LMI conditions on the existence of the H2 controller are obtained. In both cases, the desired H2 controller can be constructed through the feasible solutions of the LMIs. The proposed synthesis method is illustrated through numerical examples.
Wed, 01 Jan 2003 00:00:00 GMThttp://hdl.handle.net/10722/430622003-01-01T00:00:00Z
- Exponential filtering for uncertain Markovian jump time-delay systems with nonlinear disturbanceshttp://hdl.handle.net/10722/43066Title: Exponential filtering for uncertain Markovian jump time-delay systems with nonlinear disturbances
Authors: Wang, Z; Lam, J; Liu, X
Abstract: In this paper, we study the robust exponential filter design problem for a class of uncertain time-delay systems with both Markovian jumping parameters and nonlinear disturbances. The jumping parameters considered here are generated from a continuous-time discrete-state homogeneous Markov process, and the parameter uncertainties appearing in the state and output equations are real, time dependent, and norm bounded. The time-delay and the nonlinear disturbances are assumed to be unknown. The purpose of the problem under investigation is to design a linear, delay-free, uncertainty-independent state estimator such that, for all admissible uncertainties as well as nonlinear disturbances, the dynamics of the estimation error is stochastically exponentially stable in the mean square, independent of the time delay. We address both the filtering analysis and synthesis issues, and show that the problem of exponential filtering for the class of uncertain time-delay jump systems with nonlinear disturbances can be solved in terms of the solutions to a set of linear (quadratic) matrix inequalities. A numerical example is exploited to demonstrate the usefulness of the developed theory.
Thu, 01 Jan 2004 00:00:00 GMThttp://hdl.handle.net/10722/430662004-01-01T00:00:00Z
- Non-fragile exponential stability assignment of discrete-time linear systems with missing data in actuatorshttp://hdl.handle.net/10722/59121Title: Non-fragile exponential stability assignment of discrete-time linear systems with missing data in actuators
Authors: Shu, Z; Lam, J; Xiong, J
Abstract: This technical note is concerned with the non-fragile exponential stabilization for a class of discrete-time linear systems with missing data in actuators. The process of missing data is modeled by a discrete-time Markov chain with two state components. When no uncertainty exists in the controllers, a necessary and sufficient condition, which not only guarantees the exponential stability but also gives a lower bound on the decay rate, is established in terms of linear matrix inequalities (LMIs). Based on this condition, an LMI-based approach is provided to design a non-fragile state-feedback controller such that the closed-loop system is exponentially stable with a prescribed lower bound on the decay rate for the known missing data process and all admissible uncertainties in controllers. A numerical example is provided to show the effectiveness of the theoretical results. © 2009 IEEE.
Thu, 01 Jan 2009 00:00:00 GMThttp://hdl.handle.net/10722/591212009-01-01T00:00:00Z
- Reliable H ∞ control for affine nonlinear systemshttp://hdl.handle.net/10722/43024Title: Reliable H ∞ control for affine nonlinear systems
Authors: Yang, GH; Lam, J; Wang, J
Abstract: This paper addresses the reliable H ∞-control problems for affine nonlinear systems. Based on the Hamilton-Jacobi inequality approach developed in the H ∞-control problems for affine nonlinear systems, a method for the design of reliable nonlinear control systems is presented. The resulting nonlinear control systems are reliable in that they provide guaranteed local asymptotic stability and H ∞ performance not only when all control components are operational, but also in the case of some component outages within a prespecified subset of control components. A numerical example is also given.
Thu, 01 Jan 1998 00:00:00 GMThttp://hdl.handle.net/10722/430241998-01-01T00:00:00Z
- Robust filtering for stochastic genetic regulatory networks with time-varying delayhttp://hdl.handle.net/10722/124817Title: Robust filtering for stochastic genetic regulatory networks with time-varying delay
Authors: Wei, G; Wang, Z; Lam, J; Fraser, K; Rao, GP; Liu, X
Abstract: This paper addresses the robust filtering problem for a class of linear genetic regulatory networks (GRNs) with stochastic disturbances, parameter uncertainties and time delays. The parameter uncertainties are assumed to reside in a polytopic region, the stochastic disturbance is state-dependent described by a scalar Brownian motion, and the time-varying delays enter into both the translation process and the feedback regulation process. We aim to estimate the true concentrations of mRNA and protein by designing a linear filter such that, for all admissible time delays, stochastic disturbances as well as polytopic uncertainties, the augmented state estimation dynamics is exponentially mean square stable with an expected decay rate. A delay-dependent linear matrix inequality (LMI) approach is first developed to derive sufficient conditions that guarantee the exponential stability of the augmented dynamics, and then the filter gains are parameterized in terms of the solution to a set of LMIs. Note that LMIs can be easily solved by using standard software packages. A simulation example is exploited in order to illustrate the effectiveness of the proposed design procedures. © 2009 Elsevier Inc. All rights reserved.
Thu, 01 Jan 2009 00:00:00 GMThttp://hdl.handle.net/10722/1248172009-01-01T00:00:00Z
- Rapid incoherent control of a simple quantum system via two-step optimizationhttp://hdl.handle.net/10722/62263Title: Rapid incoherent control of a simple quantum system via two-step optimization
Authors: Dong, D; Lam, J
Abstract: A rapid incoherent control scheme for driving a simple qubit system from an initial mixed state to an arbitrary target pure state is proposed. Lhis scheme consists of two main steps: rapid purification of the initial mixed state and time optimal transition from the conditional state to the target state. Lhe first step rapidly purifies the initial mixed state into an almost-pure state of the simple qubit system through continuous measurements and feedback control by the protocol proposed in Jacobs 2003 Physical Review A 67 030301(R). The second step finds a set of suitable time optimal controls to drive the simple qubit system from the conditional state to the target state. Lhe switching time between the first step and the second step is determined by the expected purity and the resultant state is an almost-pure state with a high fidelity with the target state. Lhis rapid incoherent control scheme provides an alternative quantum engineering strategy for the rapid preparation of arbitrary pure states of a simple qubit system.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10722/622632008-01-01T00:00:00Z
- Effects of secondary loudspeaker properties on broadband feedforward active duct noise controlhttp://hdl.handle.net/10722/191397Title: Effects of secondary loudspeaker properties on broadband feedforward active duct noise control
Authors: Chan, YJ; Huang, L; Lam, J
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10722/1913972013-01-01T00:00:00Z
- L1-induced Performance Analysis and Sparse Controller Synthesis for Interval Positive Systemshttp://hdl.handle.net/10722/204212Title: L1-induced Performance Analysis and Sparse Controller Synthesis for Interval Positive Systems
Authors: Chen, X; Lam, J; Li, P; Shu, Z
Abstract: This paper is concerned with the design of L1- induced sparse controller for continuous-time positive systems with interval uncertainties. A necessary and sufficient condition for stability and L1-induced performance of positive linear systems is proposed in terms of linear inequalities. Based on this, conditions for the existence of robust state-feedback controllers are established. Moreover, the total number of all the nonzero elements of the controller gain is to be minimized, while satisfying a guaranteed level of L1-induced performance. Then, we propose an ℓ1-minimization problem to relax the ℓ0 objective function for optimization and an iterative convex optimization approach is developed to solve the conditions. Finally, an illustrative example is provided to show the effectiveness and applicability of the theoretical results.
Description: The Lecture Notes in Engineering and Computer Science(LNECS) vol. entitled: World Congress on Engineering: WCE 2013
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10722/2042122013-01-01T00:00:00Z
- On the design of robust deadbeat regulatorshttp://hdl.handle.net/10722/46599Title: On the design of robust deadbeat regulators
Authors: Lam, J; Tso, HK; Tsing, NK
Abstract: This paper considers the synthesis of state feedback gains which provide robustness against perturbation in deadbeat regulation. It is formulated as an unconstrained optimization problem. Through a posteriori perturbation analysis of the closed-loop eigenvalues, the justification of the use of a new objective function to measure the robustness of deadbeat systems is established. The objective function does not require the computation of eigenvectors and has simple analytical gradient and Hessian. A numerical example is employed to illustrate the effectiveness of the proposed method.
Mon, 01 Jan 1996 00:00:00 GMThttp://hdl.handle.net/10722/465991996-01-01T00:00:00Z
- A new criterion of delay-dependent asymptotic stability for Hopfield neural networks with time delayhttp://hdl.handle.net/10722/57195Title: A new criterion of delay-dependent asymptotic stability for Hopfield neural networks with time delay
Authors: Mou, S; Gao, H; Lam, J; Qiang, W
Abstract: In this brief, the problem of global asymptotic stability for delayed Hopfield neural networks (HNNs) is investigated. A new criterion of asymptotic stability is derived by introducing a new kind of Lyapunov-Krasovskii functional and is formulated in terms of a linear matrix inequality (LMI), which can be readily solved via standard software. This new criterion based on a delay fractioning approach proves to be much less conservative and the conservatism could be notably reduced by thinning the delay fractioning. An example is provided to show the effectiveness and the advantage of the proposed result. © 2008 IEEE.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10722/571952008-01-01T00:00:00Z
- A delay-partitioning projection approach to stability analysis of neutral systemshttp://hdl.handle.net/10722/159037Title: A delay-partitioning projection approach to stability analysis of neutral systems
Authors: Du, B; Lam, J; Shu, Z
Abstract: This paper introduces a new effective approach to study the stability of neutral systems. By employing a special Lyapunov-Krasovskii functional form based on delay partitioning, delay-dependent stability criteria are established for the nominal and the uncertain case (polytopic type) in terms of linear matrix inequalities (LMI). Numerical examples are employed to illustrate that the delay-partitioning projection approach can be applied to estimate the upper bounds for the delays for the system to maintain stability. Judging from these numerical results, the stability criteria obtained are less conservative than those of existing methods. Copyright © 2007 International Federation of Automatic Control All Rights Reserved.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10722/1590372008-01-01T00:00:00Z
- Robust H∞ control of markovian jump linear systems with uncertain switching probabilitieshttp://hdl.handle.net/10722/159035Title: Robust H∞ control of markovian jump linear systems with uncertain switching probabilities
Authors: Xiong, J; Lam, J
Abstract: This paper is concerned with the robust H∞ control of Markovian jump linear systems with uncertain switching probabilities. The uncertain system under consideration involves norm-bounded uncertainties in system matrices and element-wise bounded uncertainties in the mode transition rate matrix. A new criterion is established to test the robust H ∞ performance in terms of linear matrix inequalities and a su±cient condition is addressed for constructing a robust state-feedback controller such that the closed-loop system is robustly mean square stable and has the desired H∞ performance level. A globally convergent algorithm involving convex optimization is also proposed to find such controllers effectively. Finally, a numerical example illustrates the usefulness of the developed theory. Copyright © 2005 IFAC.
Sat, 01 Jan 2005 00:00:00 GMThttp://hdl.handle.net/10722/1590352005-01-01T00:00:00Z
- Delay-dependent exponential estimates of stochastic neural networks with time delayhttp://hdl.handle.net/10722/158963Title: Delay-dependent exponential estimates of stochastic neural networks with time delay
Authors: Zhan, S; Lam, J
Abstract: This paper is concerned with the exponential estimating problem for a class of stochastic neural networks with time delay. A sufficient condition, which does not only guarantee the exponential stability but also gives the estimates of decay rate and decay coefficient, is established in terms of a new Lyapunov-Krasovskii functional and the linear matrix inequality (LMI) technique. The estimating procedure is implemented by solving a set of LMIs, which can be checked easily by effective algorithms. A numerical example is provided to illustrate the effectiveness of the theoretical results. © Springer-Verlag Berlin Heidelberg 2006.
Sun, 01 Jan 2006 00:00:00 GMThttp://hdl.handle.net/10722/1589632006-01-01T00:00:00Z
- Delay-dependent stability condition for uncertain linear 2-D state-delayed systemshttp://hdl.handle.net/10722/158980Title: Delay-dependent stability condition for uncertain linear 2-D state-delayed systems
Authors: Paszke, W; Lam, J; Gałkowski, K; Xu, S; Kummert, A
Abstract: This paper addresses the problem of robust stability for uncertain two-dimensional systems with delays in the state. The uncertainty is assumed to be of norm-bounded form. To solve this problem, the Lyapunov second method is used. The resulting condition is written in terms of linear matrix inequalities and it is dependent on the size of delays. This fact allows us to reduce the conservatism in the stability analysis of two-dimensional systems with state delays. A illustrative example is given to illustrate the theoretical developments. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttp://hdl.handle.net/10722/1589802006-01-01T00:00:00Z
- Stabilization of a class of uncertain "wave" discrete linear repetitive processeshttp://hdl.handle.net/10722/158981Title: Stabilization of a class of uncertain "wave" discrete linear repetitive processes
Authors: Galkowski, K; Cichy, B; Rogers, E; Lam, J
Abstract: Repetitive processes are a distinct class of two-dimensional (2D) systems (i.e. information propagation in two independent directions occurs) of both systems theoretic and applications interest. They cannot be controlled by direct extension of existing techniques from either standard (termed ID here) or (most often) 2D systems theory. In this paper we continue the development of a systems theory for a recently proposed model of these processes necessary to represent terms which arise in some applications areas but are not included in the currently used models. The new results are on the design of control laws for stabilization in the case when there is uncertainty associated with the defining state-space model. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttp://hdl.handle.net/10722/1589812006-01-01T00:00:00Z
- Global exponential estimates of stochastic Cohen-Grossberg neural networks with time delayhttp://hdl.handle.net/10722/158983Title: Global exponential estimates of stochastic Cohen-Grossberg neural networks with time delay
Authors: Zhan, S; Lam, J
Abstract: This paper is concerned with the exponential estimating problem for Cohen-Grossberg neural networks with time delay and stochastic disturbance. A sufficient condition, which does not only guarantee the global exponential stability but also provides more exact characterization on the decay rate and the coefficient, is established in terms of the Lyapunov-Krasovskii functional approach and the linear matrix inequality (LMI) technique. The estimates of the decay rate and the coefficient are obtained by solving a set of LMIs, which can be checked easily by effective algorithms. In addition, slack matrices are introduced to reduce the conservatism of the condition. A numerical example is provided to illustrate the effectiveness of the theoretical results. © 2007 IEEE.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10722/1589832008-01-01T00:00:00Z
- Delay-dependent output-feedback stabilisation of discrete-time systems with time-varying state delayhttp://hdl.handle.net/10722/158942Title: Delay-dependent output-feedback stabilisation of discrete-time systems with time-varying state delay
Authors: Gao, H; Lam, J; Wang, C; Wang, Y
Abstract: The output-feedback stabilisation problem is solved for discrete-time systems with time-varying delay in the state. A stability condition is first proposed, which is dependent on the minimum and maximum delay bounds. Based on this easily verifiable stability condition, the problems of stabilisation by static and dynamic output-feedback controllers are solved within the linear matrix inequality (LMI) framework. Since the obtained conditions for the existence of admissible controllers are not expressed as strict LMI conditions, the cone complementary linearisation procedure is exploited to solve the nonconvex feasibility problem. In addition, the obtained results, including stability analysis, static output-feedback stabilisation and dynamic output-feedback stabilisation are further extended to discrete time-delay systems with norm-bounded uncertain parameters. Numerical examples are also presented to illustrate the applicability of the developed results.
Thu, 01 Jan 2004 00:00:00 GMThttp://hdl.handle.net/10722/1589422004-01-01T00:00:00Z
- Multiplicative approximation of multivariable systems using Hankel norm criterionhttp://hdl.handle.net/10722/158892Title: Multiplicative approximation of multivariable systems using Hankel norm criterion
Authors: Matson, JB; Lam, J; Anderson, BDO; James, B
Abstract: Control system design specifications are commonly given in terms of log-magnitude quantities (dB). This induces a multiplicative or relative error criterion for plant model reduction. Techniques from the theory of additive Hankel norm approximation and spectral factorization are synthesised to produce a multiplicative approximant of a possibly unstable or nonsquare plant. It is shown that the reduced-order model preserves the right half plane poles and zeros of the original system. Explicit state-space formulae are provided for the construction of the reduced order model and its error properties discussed.
Wed, 01 Jan 1992 00:00:00 GMThttp://hdl.handle.net/10722/1588921992-01-01T00:00:00Z
- Solution of robust pole-placement problem via gradient flowhttp://hdl.handle.net/10722/158900Title: Solution of robust pole-placement problem via gradient flow
Authors: Lam, J; Yan, W
Abstract: This paper provides a computational procedure for a type of robust pole-placement problem. By exploiting the differentiability nature of the objective function based on the Frobenius norm condition number, the minimization problem is formulated in terms of a gradient flow to which standard ODE numerical routines can be applied. It is shown that a minimum point exists for the objective function. The algorithm is efficient and faces no singularity problem with the resulting eigenvector matrix. A numerical example is used to illustrate the technique and comparison to other methods is made.
Sat, 01 Jan 1994 00:00:00 GMThttp://hdl.handle.net/10722/1589001994-01-01T00:00:00Z
- Gradient flow approach to robust pole assignment in second-order systemshttp://hdl.handle.net/10722/158913Title: Gradient flow approach to robust pole assignment in second-order systems
Authors: Chan, HC; Lam, James; Ho, Daniel WC
Abstract: Robust pole assignment for second-order systems is considered. It is shown that assignment can be achieved by solving a linear matrix equation or linear system. An objective function measuring the robustness of the closed-loop spectrum is minimized via gradient flow.
Mon, 01 Jan 1996 00:00:00 GMThttp://hdl.handle.net/10722/1589131996-01-01T00:00:00Z
- Design of reliable controllers for symmetric composite systems: Primary contingency casehttp://hdl.handle.net/10722/158915Title: Design of reliable controllers for symmetric composite systems: Primary contingency case
Authors: Yang, GuangHong; Wang, Jinaliang; Soh, Cheong Boon; Lam, James
Abstract: This paper discusses the reliable controller design problem for symmetric composite systems composed of several identical subsystems. A reliable controller design procedure is presented in terms of the solutions to the Algebraic Riccati Equations. The order of these AREs is much lower than that of the symmetric composite system. The resulting closed-loop system is reliable in that it provide guaranteed internal stability and H∞ performance when all sensors and actuators are operational as well as when the sensors or actuators of a prescribed subsystem experiences an outage.
Mon, 01 Jan 1996 00:00:00 GMThttp://hdl.handle.net/10722/1589151996-01-01T00:00:00Z
- Decentralized HINF controller design for nonlinear systemshttp://hdl.handle.net/10722/158917Title: Decentralized HINF controller design for nonlinear systems
Authors: Yang, GuangHong; Wang, Jianliang; Soh, CB; Lam, James
Abstract: Considering a nonlinear system ∑ described by a specified system of equations for i=1,...q where x ∈ X ⊂ Rn with 0 ∈ Rn is the state; ui ∈ Rm(i) local control; yi ∈ Rp(i) local measurement; w0 and wi's square-integrable disturbances; and z regulated output. The functions f(x), g1(x), h1(x), g2i(x) and h2i(x) (i = 1, ···, q) are all known and smooth in X with f(0) = 0, h1(0) = 0 and h2i(0) = 0 (i = 1, ···, q). A Decentralized H∞ Controller Design (DHCD) was evaluated to find the controllers of the form qq given the system of ∑ of (1)-(3) and a positive constant γ. A design method for local observer gains Li(ξi) (i = 1, ···, q) was presented to the nonlinear matrix inequality.
Wed, 01 Jan 1997 00:00:00 GMThttp://hdl.handle.net/10722/1589171997-01-01T00:00:00Z
- New observer-based guaranteed cost control for neutral delay systemshttp://hdl.handle.net/10722/158943Title: New observer-based guaranteed cost control for neutral delay systems
Authors: Chen, B; Lam, J; Xu, S
Abstract: This paper considers the problem of guaranteed cost control for a class of neutral delay systems. Unlike the commonly used quadratic cost function involving the state, a cost function involving the delayed state is considered. This naturally leads to a memory state feedback such that the resulting closed-loop system is not only asymptotically stable but also guarantees an adequate level of performance. An observer-based output feedback guaranteed cost control problem is addressed. A sufficient condition for the existence of a guaranteed cost controller is given in terms of the feasibility condition of a linear matrix inequality. Finally, two numerical examples are used to demonstrate the effectiveness of the approach proposed.
Thu, 01 Jan 2004 00:00:00 GMThttp://hdl.handle.net/10722/1589432004-01-01T00:00:00Z
- Approximation of discrete-time systems with time-varying delay: Hankel norm criterionhttp://hdl.handle.net/10722/158944Title: Approximation of discrete-time systems with time-varying delay: Hankel norm criterion
Authors: Gao, H; Lam, J; Wang, C
Abstract: The problem of Hankel norm model reduction for discrete-time systems with time-varying state delay is investigated. For a given stable system, this paper focuses on constructing stable reduced-order models under the Hankel norm error criterion. Two different approaches are proposed to solve this problem. One is based on the cone complementarity linearization idea, which casts the model reduction into a sequential minimization problem subject to linear matrix inequality constraints, and the other casts the model reduction into a convex optimization problem by using a linearization procedure. A numerical example is provided to show the effectiveness of the proposed theories.
Thu, 01 Jan 2004 00:00:00 GMThttp://hdl.handle.net/10722/1589442004-01-01T00:00:00Z
- Sliding-mode control for uncertain neutral delay systemshttp://hdl.handle.net/10722/158946Title: Sliding-mode control for uncertain neutral delay systems
Authors: Niu, Y; Lam, J; Wang, X
Abstract: The problem of sliding-mode control for a class of neutral delay systems with uncertainties in both the state matrices and the input matrix is considered. By selecting a sliding surface depending on the current state and delayed state, the paper gives a sufficient condition in terms of linear matrix inequalities (LMIs) such that the closed-loop system is guaranteed to be asymptotically stable. When LMIs are feasible, the design of the sliding surface and the sliding-mode control law can be easily obtained by convex optimisation. State trajectories are attracted onto the sliding surface in a finite time and remain there for all subsequent time. A simulation illustrates the application of the method.
Thu, 01 Jan 2004 00:00:00 GMThttp://hdl.handle.net/10722/1589462004-01-01T00:00:00Z
- BALANCED REALISATION AND HANKEL-NORM APPROXIMATION OF SYSTEMS INVOLVING DELAYS.http://hdl.handle.net/10722/158885Title: BALANCED REALISATION AND HANKEL-NORM APPROXIMATION OF SYSTEMS INVOLVING DELAYS.
Authors: Glover, K; Lam, J; Partington, JR
Abstract: Approximation of the transfer functions G(s)e** minus S**T (with G(s) rational) is considered via the singular values, sigma //i, of its Hankel operator. It is shown how to calculate sigma //i and the corresponding Schmidt vectors for this class of transfer functions. Then bounds on the singular values of more general Hankel operators are derived, giving asymptotic estimates for the sigma //i. The results can be used to construct balanced realizations or Hankel norm approximations.
Wed, 01 Jan 1986 00:00:00 GMThttp://hdl.handle.net/10722/1588851986-01-01T00:00:00Z
- On the transient and steady-state estimates of interval genetic regulatory networkshttp://hdl.handle.net/10722/124845Title: On the transient and steady-state estimates of interval genetic regulatory networks
Authors: Li, P; Lam, J; Shu, Z
Abstract: This paper is concerned with the transient and steady-state estimates of a class of genetic regulatory networks (GRNs). Some sufficient conditions, which do not only present the transient estimate but also provide the estimates of decay rate and decay coefficient of the GRN with interval parameter uncertainties (interval GRN), are established by means of linear matrix inequality (LMI) and LyapunovKrasovskii functional. Moreover, the steady-state estimate of the proposed GRN model is also investigated. Furthermore, it is well known that gene regulation is an intrinsically noisy process due to intracellular and extracellular noise perturbations and environmental fluctuations. Then, by utilizing stochastic differential equation theory, the obtained results are extended to the case with noise perturbations due to natural random fluctuations. All the conditions are expressed within the framework of LMIs, which can easily be computed by using standard numerical software. A three-gene network is provided to illustrate the effectiveness of the theoretical results. © 2006 IEEE.
Fri, 01 Jan 2010 00:00:00 GMThttp://hdl.handle.net/10722/1248452010-01-01T00:00:00Z
- Decentralized H ∞ control for air traffic flow networks modeled by a class of compartmental systemshttp://hdl.handle.net/10722/126302Title: Decentralized H ∞ control for air traffic flow networks modeled by a class of compartmental systems
Authors: Li, P; Lam, J
Abstract: In this paper, we study the decentralized H ∞ control problem for air traffic flow (ATF) networks. By dividing the airspace into a number of interconnected regions, we first characterize the traffic flow dynamics by means of a compartmental system approach, and formulate the ATF control problem in a decentralized way, where the controller gain matrix is required to be diagonal and element-restricted. To solve the problem, a novel characterization is presented to ensure that the closed-loop system is asymptotically stable with a prescribed H ∞ performance. T hen, a necessary and sufficient condition for the existence of a required controller is proposed and an iterative linear matrix inequality approach is further developed to solve the design condition. Finally, a simple ATF network is used to show the applicability of the obtained results. ©2010 IEEE.
Fri, 01 Jan 2010 00:00:00 GMThttp://hdl.handle.net/10722/1263022010-01-01T00:00:00Z
- Further results on exponential estimates of markovian jump systems with mode-dependent time-varying delayshttp://hdl.handle.net/10722/139423Title: Further results on exponential estimates of markovian jump systems with mode-dependent time-varying delays
Authors: Gao, H; Fei, Z; Lam, J; Du, B
Abstract: This technical note studies the problem of exponential estimates for Markovian jump systems with mode-dependent interval time-varying delays. A novel LyapunovKrasovskii functional (LKF) is constructed with the idea of delay partitioning, and a less conservative exponential estimate criterion is obtained based on the new LKF. Illustrative examples are provided to show the effectiveness of the proposed results. © 2010 IEEE.
Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/10722/1394232011-01-01T00:00:00Z
- Stochastic stability analysis of fuzzy Hopfield neural networks with time-varying delayshttp://hdl.handle.net/10722/43012Title: Stochastic stability analysis of fuzzy Hopfield neural networks with time-varying delays
Authors: Huang, H; Ho, DWC; Lam, J
Abstract: The ordinary Takagi-Sugeno (TS) fuzzy models have provided an approach to represent complex nonlinear systems to a set of linear sub-models by using fuzzy sets and fuzzy reasoning. In this paper, stochastic fuzzy Hopfield neural networks with time-varying delays (SFVDHNNs) are studied. The model of SFVDHNN is first establisbed as a modified TS fuzzy model in which the consequent parts are composed of a set of stochastic Hopfield neural networks with time-varying delays. Secondly, the global exponential stability in the mean square for SFVDHNN is studied by using the Lyapunov-Krasovskii approach. Stability criterion is derived in terms of linear matrix inequalities (LMIs), which can be effectively solved by some standard numerical packages. © 2005 IEEE.
Sat, 01 Jan 2005 00:00:00 GMThttp://hdl.handle.net/10722/430122005-01-01T00:00:00Z
- Stabilization of markovian systems via probability rate synthesis and output feedbackhttp://hdl.handle.net/10722/124854Title: Stabilization of markovian systems via probability rate synthesis and output feedback
Authors: Feng, JE; Lam, J; Shu, Z
Abstract: This technical note is concerned with the stabilization problem of Markovian jump linear systems via designing switching probability rate matrices and static output-feedback gains. A novel necessary and sufficient condition is established to characterize the switching probability rate matrices that guarantee the mean square stability of Markovian jump linear systems. Based on this, a necessary and sufficient condition is provided for the existence of desired controller gains and probability rate matrices. Extensions to the polytopic uncertain case are also provided. All the conditions are formulated in terms of linear matrix inequalities with some equality constraints, which can be solved by two modified cone complementarity linearization algorithms. Examples are given to show the effectiveness of the proposed method. © 2010 IEEE.
Fri, 01 Jan 2010 00:00:00 GMThttp://hdl.handle.net/10722/1248542010-01-01T00:00:00Z
- New approach to mixed H2/H∞ filtering for polytopic discrete-time systemshttp://hdl.handle.net/10722/44926Title: New approach to mixed H2/H∞ filtering for polytopic discrete-time systems
Authors: Gao, H; Lam, J; Xie, L; Wang, C
Abstract: This paper revisits the problem of mixed H2/H∞ filtering for polytopic discrete-time systems. Differing from previous results in the quadratic framework, the filter design makes full use of the parameter-dependent stability idea: Not only is the filter dependent of the parameters (which are assumed to reside in a polytope and be measurable online), but in addition, the Lyapunov matrices are different for the entire polytope domain, as well as for different channels with respect to the mixed performances. These ideas are realized by introducing additional slack variables to the well-established performance conditions and by employing new bounding techniques, which results in a much less conservative filter design method. A numerical example is presented to illustrate the effectiveness and advantage of the developed filter design method. © 2005 IEEE.
Sat, 01 Jan 2005 00:00:00 GMThttp://hdl.handle.net/10722/449262005-01-01T00:00:00Z
- Stabilization of networked control systems with a logic ZOHhttp://hdl.handle.net/10722/59034Title: Stabilization of networked control systems with a logic ZOH
Authors: Xiong, J; Lam, J
Abstract: The technical note is concerned with the stabilization problem of networked control systems. A general framework is proposed firstly, where the zero-order hold has the logical capability of choosing the newest control input packet. The continuous-time process is discretized as a system with input delays. Then a sufficient condition for testing the stability of the discretized system and two sufficient conditions for designing a stabilizing controller are established based upon the Lyapunov theory. Finally numerical examples and simulations are used to illustrate the developed theory. © 2009 IEEE.
Thu, 01 Jan 2009 00:00:00 GMThttp://hdl.handle.net/10722/590342009-01-01T00:00:00Z
- Positive observers for positive interval linear discrete-time delay systemshttp://hdl.handle.net/10722/126315Title: Positive observers for positive interval linear discrete-time delay systems
Authors: Li, P; Lam, J; Shu, Z
Abstract: Linear matrix inequalities (LMIs) provide a powerful analysis and synthesis framework for linear systems. In this paper, we use LMIs to develop positive observers for positive linear discrete-time (PLDT) systems with both parameter uncertainties and time delay. Specifically, we first present some equivalent conditions for the asymptotic stability of positive linear discrete-time delay systems, which will be employed to design the positive observers. Then, necessary and sufficient conditions are proposed to check the existence of positive observers for interval PLDT systems with time delay when the positivity of the error signals is considered, and the observer matrices to be constructed can be easily obtained through the solutions of LMIs. Finally, a numerical example is provided to demonstrate the efficacy of the proposed approach. ©2009 IEEE.
Thu, 01 Jan 2009 00:00:00 GMThttp://hdl.handle.net/10722/1263152009-01-01T00:00:00Z
- Robust H∞ filtering for uncertain 2-D continuous systemshttp://hdl.handle.net/10722/43013Title: Robust H∞ filtering for uncertain 2-D continuous systems
Authors: Xu, S; Lam, J; Zou, Y; Lin, Z; Paszke, W
Abstract: This paper considers the problem of robust H∞ filtering for uncertain two-dimensional (2-D) continuous systems described by the Roesser state-space model. The parameter uncertainties are assumed to be norm-bounded in both the state and measurement equations. The purpose is the design of a 2-D continuous filter such that for all admissible uncertainties, the error system is asymptotically stable, and the H∞ norm of the transfer function, from the noise signal to the estimation error, is below a prespecified level. A sufficient condition for the existence of such filters is obtained in terms of a set of linear matrix inequalities (LMIs). When these LMIs are feasible, an explicit expression of a desired H∞ filter is given. Finally, a simulation example is provided to demonstrate the effectiveness of the proposed method. © 2005 IEEE.
Sat, 01 Jan 2005 00:00:00 GMThttp://hdl.handle.net/10722/430132005-01-01T00:00:00Z
- Fixed-order robust H∞filter design for Markovian jump systems with uncertain switching probabilitieshttp://hdl.handle.net/10722/44928Title: Fixed-order robust H∞filter design for Markovian jump systems with uncertain switching probabilities
Authors: Xiong, J; Lam, J
Abstract: This paper discusses the fixed-order robust H∞ filtering problem for a class of Markovian jump linear systems with uncertain switching probabilities. The uncertainties under consideration are assumed to be norm-bounded in the system matrices and to be element wise bounded in the mode transition rate matrix, respectively. First, a criterion based on linear matrix inequalities is provided for testing the H∞ filtering level of a filter over all the admissible uncertainties. Then, a sufficient condition for the existence of the fixed-order robust H∞ filters is established in terms of the solvability of a set of linear matrix inequalities with equality constraints. To determine the filter, a globally convergent algorithm involving convex optimization is suggested. Finally, a numerical example is used to illustrate that the developed theory is more effective than the existing results. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttp://hdl.handle.net/10722/449282006-01-01T00:00:00Z
- Induced l2 and generalized H2 filtering for systems with repeated scalar nonlinearitieshttp://hdl.handle.net/10722/44929Title: Induced l2 and generalized H2 filtering for systems with repeated scalar nonlinearities
Authors: Gao, H; Lam, J; Wang, C
Abstract: This paper provides complete results on the filtering problem for a class of nonlinear systems described by a discrete-time state equation containing a repeated scalar nonlinearity as in recurrent neural networks. Both induced l2 and generalized H2 indexes are introduced to evaluate the filtering performance. For a given stable discrete-time systems with repeated scalar nonlinearities, our purpose is to design a stable full-order or reduced-order filter with the same repeated scalar nonlinearities such that the filtering error system is asymptotically stable and has a guaranteed induced l2 or generalized H2 performance. Sufficient conditions are obtained for the existence of admissible filters. Since these conditions involve matrix equalities, the cone complementarity linearization procedure is employed to cast the nonconvex feasibility problem into a sequential minimization problem subject to linear matrix inequalities, which can be readily solved by using standard numerical software. If these conditions are feasible, a desired filter can be easily constructed. These filtering results are further extended to discrete-time systems with both state delay and repeated scalar nonlinearities. The techniques used in this paper are very different from those used for previous controller synthesis problems, which enable us to circumvent the difficulty of dilating a positive diagonally dominant matrix. A numerical example is provided to show the applicability of the proposed theories. © 2005 IEEE.
Sat, 01 Jan 2005 00:00:00 GMThttp://hdl.handle.net/10722/449292005-01-01T00:00:00Z
- Simultaneous stabilization via static output feedback and state feedbackhttp://hdl.handle.net/10722/43027Title: Simultaneous stabilization via static output feedback and state feedback
Authors: Cao, YY; Sun, YX; Lam, J
Abstract: In this paper, the simultaneous stabilization problem is considered using the matrix inequality approach. Some necessary and sufficient conditions for simultaneous stabilizability of r strictly proper multi-input/multi-output (MIMO) plants via static output feedback and state feedback are obtained in the form of coupled ARI's. It is shown that any such stabilizing feedback gain is the solution of some coupled linear quadratic control problems where every cost functional has a suitable cross term. A heuristic iterative algorithm based on the linear matrix inequality (LMI) technique is presented to solve the coupled matrix inequalities. The effectiveness of the approach is illustrated by numerical example.
Fri, 01 Jan 1999 00:00:00 GMThttp://hdl.handle.net/10722/430271999-01-01T00:00:00Z