H.K. Lam | King's College London (original) (raw)

Papers by H.K. Lam

2013 IEEE International Conference on Robotics and Automation, 2013

IET Control Theory & Applications, 2010

Abstract This study investigates the systems stability of fuzzy-model-based (FMB) control systems... more Abstract This study investigates the systems stability of fuzzy-model-based (FMB) control systems. Based on the TS fuzzy model representing the non-linear system, a fuzzy controller using grid-point (GP) technique is proposed to close the feedback loop. A GP is defined as the sub-operating domain of the non-linear system. For each GP, a corresponding GP fuzzy controller is employed to control the system. As the non-linearity in each GP is lower compared to that of the full operating domain, it is in favour of yielding relaxed stability ...

Journal of the Franklin Institute, 2012

This paper presents the stability analysis of nonlinear-function fuzzy-model-based (FMB) control ... more This paper presents the stability analysis of nonlinear-function fuzzy-model-based (FMB) control systems. A fuzzy model with nonlinear function terms is proposed to represent nonlinear plants. A fuzzy controller with the nonlinear function terms is then proposed to close the feedback loop. The nonlinear function terms enhance the capability of fuzzy modelling and feedback compensation. Following the linear-matrix-inequality (LMI) based stability analysis approach for the traditional FMB control systems, it will lead to stability ...

IEEE Trans. Fuzzy Systems, Feb 2014

This paper investigates the stability of polynomial-fuzzy-model-based (PFMB) control system, whic... more This paper investigates the stability of polynomial-fuzzy-model-based (PFMB) control system, which is formed by a polynomial fuzzy model and a polynomial fuzzy controller connected in a closed loop. To enhance the design flexibility, the number of rules and the shape of premise membership functions of the polynomial fuzzy controller are considered to be chosen freely and are different from those of the polynomial fuzzy model, however, which make the stability analysis more difficult and potentially lead to conservative stability analysis result. A sum-of-squares (SOS)-based stability analysis approach using the Lyapunov stability theory is proposed to investigate the stability of the PFMB control systems and synthesize the polynomial fuzzy controller. To facilitate the stability analysis and relax the stability analysis result, the property of the membership functions and the boundary information of the membership grades and premise variables are taken into account in the stability analysis and incorporated into the SOS-based stability conditions. A simulation example is given to illustrate the effectiveness of the proposed approach.

IEEE Trans. Industrial Electronics, Feb 2014

This paper focuses on designing interval type-2 (IT2) control for nonlinear systems subject to pa... more This paper focuses on designing interval type-2 (IT2) control for nonlinear systems subject to parameter uncertainties. To facilitate the stability analysis and control synthesis, an IT2 Takagi-Sugeno (T-S) fuzzy model is employed to represent the dynamics of nonlinear systems of which the parameter uncertainties are captured by IT2 membership functions characterized by the lower and upper membership functions. A novel IT2 fuzzy controller is proposed to perform the control process, where the membership functions and number of rules can be freely chosen and different from those of the IT2 T-S fuzzy model. Consequently, the IT2 fuzzy-model-based (FMB) control system is with imperfectly matched membership functions, which hinders the stability analysis. To relax the stability analysis for this class of IT2 FMB control systems, the information of footprint of uncertainties and the lower and upper membership functions are taken into account for the stability analysis. Based on the Lyapunov stability theory, some stability conditions in terms of linear matrix inequalities are obtained to determine the system stability and achieve the control design. Finally, simulation and experimental examples are provided to demonstrate the effectiveness and the merit of the proposed approach.

… , 2007. CEC 2007. …, 2007

Journal of Intelligent Learning Systems and …, 2011

Neural Networks, 2006. IJCNN' …, 2006

International Journal of Computational …, 2009

This paper presents the graffiti interpretation of one-stroke handwritten digits (0 to 9) and com... more This paper presents the graffiti interpretation of one-stroke handwritten digits (0 to 9) and commands (backspace, carriage return and space) using support vector machines (SVMs). A number of SVM-based graffiti interpreters are proposed for the recognition of graffiti. The performance of the proposed SVM-based graffiti interpreters subject to various kernel functions and parameters are investigated. Simulation and experimental results are presented to show the applicability and the merits of various graffiti interpreters.

Systems, Man, and Cybernetics, Part B: …, 2004

Neural Networks, 2002. …, 2002

Automatica, 2011

This paper presents the stability analysis and control synthesis for a sampled-data control syste... more This paper presents the stability analysis and control synthesis for a sampled-data control system which consists of a nonlinear plant and an output-feedback sampled-data polynomial controller connected in a closed loop. The output-feedback sampled-data polynomial controller, which can be implemented by a microcontroller or a digital computer, is proposed to stabilize the nonlinear plant. Based on the Lyapunov stability theory, stability conditions in terms of sum of squares are obtained to guarantee the stability and to aid the design of a polynomial controller. A simulation example is given to demonstrate the effectiveness of the proposed control approach.

International Journal of Bifurcation and Chaos, 2007

This paper proposes a linear sampled-data controller for the stabilization of chaotic system. The... more This paper proposes a linear sampled-data controller for the stabilization of chaotic system. The system stabilization and performance issues will be investigated. Stability conditions will be derived based on the Lyapunov approach. The findings of the maximum sampling period and the feedback gain of controller, and the optimization of system performance will be formulated as a generalized eigenvalue minimization problem. Based on the analysis result, a stable linear sampled-data controller can be realized systematically to stabilize a chaotic ...

Physics Letters A, 2010

This Letter presents the chaos synchronization of two discrete-time generalized Hénon map, namely... more This Letter presents the chaos synchronization of two discrete-time generalized Hénon map, namely the drive and response systems. A polynomial controller is proposed to drive the system states of the response system to follow those of the drive system. The system stability of the error system formed by the drive and response systems and the synthesis of the polynomial controller are investigated using the sum-of-squares (SOS) technique. Based on the Lyapunov stability theory, stability conditions in terms of SOS are derived to guarantee the system stability and facilitate the controller synthesis. By satisfying the SOS-based stability conditions, chaotic synchronization is achieved. The solution of the SOS-based stability conditions can be found numerically using the third-party Matlab toolbox SOSTOOLS. A simulation example is given to illustrate the merits of the proposed polynomial control approach.

Abstract This paper presents the stability analysis, synthesis, and performance optimization of a... more Abstract This paper presents the stability analysis, synthesis, and performance optimization of a radial-basis-function neural-network based control system. Global stability conditions will be derived in terms of matrix measure. Based on the derived stability conditions, connection weights of the radial-basis-function neural-network based controller can be optimized by genetic algorithm (GA) subject to the system stability. Furthermore, the system performance will also be optimized by the GA. An application example on stabilizing an ...

This paper describes the design and development of a path planning method for Micro Robot Soccer ... more This paper describes the design and development of a path planning method for Micro Robot Soccer Tournament (MIROSOT). Every object in the stadium is given a working layer which is decomposed into a fixed number of small areas. We propose to assign values to different small areas of the layer according to the object's movement. The final path is obtained by combining the small areas of the layers and getting the path with the smallest values. Since the host computer uses only a simple equation to calculate the value of each small area, this algorithm requires only a low computing power, and the speed of path generation is very fast. A simulation program was developed to test the algorithm's performance

… Electronics Society, 2001 …, 2001

Abstract Presents a decision maker, which will select the appropriate tactics and actions for soc... more Abstract Presents a decision maker, which will select the appropriate tactics and actions for soccer robots according to the condition of a tournament. The selected tactic will be employed to assign each home robot an action to play the game. The decision maker consists of a tactic database, an action database, a tactic selection algorithm, a tactic selector and an action selector. Simulation results are given to show the merits of the proposed algorithm