Showing papers by "Guo-Ping Liu published in 2006"

On designing of sliding-mode control for stochastic jump systems

Abstract: In this note, we consider the problems of stochastic stability and sliding-mode control for a class of linear continuous-time systems with stochastic jumps, in which the jumping parameters are modeled as a continuous-time, discrete-state homogeneous Markov process with right continuous trajectories taking values in a finite set. By using Linear matrix inequalities (LMIs) approach, sufficient conditions are proposed to guarantee the stochastic stability of the underlying system. Then, a reaching motion controller is designed such that the resulting closed-loop system can be driven onto the desired sliding surface in a limited time. It has been shown that the sliding mode control problem for the Markovian jump systems is solvable if a set of coupled LMIs have solutions. A numerical example is given to show the potential of the proposed techniques.

Design and stability analysis of networked control systems with random communication time delay using the modified MPC

Abstract: This paper describes a novel control technique to deal with networked control systems with random communication time delay, which is known to highly degrade the control performance of the controlled system. This problem can be solved using a modified model predictive control, which uses the future control sequence to compensate for the forward communication time delay. Also, using a model predictor, the time delay in the backward channel can be compensated as well. Another key part of this paper is to analyse the stability of the networked control systems. The analytical criteria are obtained for both fixed and random communication time delays. The simulation results and practical experiments illustrate that the proposed controller design is realistic.

Predictive Control of Networked Systems with Random Delay and Data Dropout

Abstract: This paper is concerned with the stochastic stability analysis of networked control systems with random network delay A new control scheme termed networked predictive control is proposed This scheme mainly consists of the control prediction generator and network delay compensator The control prediction generator provides a set of future control predictions to make the closed-loop system achieve the desired control performance and the network delay compensator removes the effects of the network transmission delay and data dropout The stochastic stability criteria of the closed-loop networked predictive control systems are derived A numerical example shows the effectiveness of the proposed scheme

Improving the performance of the ALSTOM baseline controller using multiobjective optimisation

Abstract: The authors present a multiobjective optimisation design approach to improve the performance of the ALSTOM Benchmark Challenge baseline controller. As the gasifier process is complex and non-linear, with a high degree of cross coupling of the variables, manual tuning of the controllers is difficult. The use of a multiobjective optimisation method allows the simultaneous tuning of multiple controllers, seeking a trade-off between the different performance objectives. A further example using the same multiobjective optimisation method shows how the performance of the baseline controller can be improved by the addition of extra proportional controllers to reduce the fluctuation due to a sine-wave pressure disturbance. This control structure is then simplified using a genetic algorithm search procedure, to find the structure with the lowest error.

Design and implementation of networked predictive control systems based on round trip time delay measurement

Abstract: There are two random network transmission delays in networked control systems: forward and backward channel delays, which degrade the control performance significantly and even make the system unstable. In this paper, a predictive control method is presented to compensate the random delays. By using Diophantine equation, future control sequences for every possible time delay are generated, which are transmitted to the plant side in a single packet. The prediction is not based on individual forward and backward delays which are difficult to measure separately in a practical system but the round trip time (RTT) delay which is the sum of forward and backward delays, and is easy to measure. An active plant side and an event-driven controller are also introduced to achieve the aim. To illustrate the control performance improvement of the proposed control scheme, the results of off-line and real-time simulations and experiments for a practical servo control system are presented.

State Feedback Control of Networked Systems—an LMI Approach

Abstract: This paper is concerned with the design of state feedback controller for networked control systems. The networked control system with random network induced delay is modeled as a discrete-time system with uncertainties and two time-varying input delays. Based on this model, a method to design a state feedback controller is proposed. The controller gain can be obtained by solving a set of linear matrix inequalities. Two examples are given to illustrate the effectiveness of the method.

Robust adaptive sliding mode control for uncertain time-delay systems

Abstract: This paper is devoted to robust adaptive sliding mode control for time-delay systems with mismatched parametric uncertainties. Sufficient conditions for the existence of linear sliding surfaces are given in terms of matrix inequalities, by which the corresponding adaptive reaching motion controller is also designed.

Networked Predictive Control of Internet/Intranet Based Systems

Abstract: The paper discusses predictive control of Internet/intranet based systems. To deal with the random communication delay on the Internet/intranet, the networked predictive control scheme is introduced. The key part of this scheme is how to generate the control prediction. The analytical stability criterion of the closed-loop networked predictive control systems is derived. The networked predictive control scheme is illustrated using practical intranet/Internet based control experiments.

H ∞ control for Networked Control Systems in Presence of Random Network Delay and Data Dropout

Abstract: The paper is concerned with the problem of Hinfin control of networked control systems with random network delay. A new control scheme termed networked predictive control is proposed. This scheme mainly consists of the control prediction generator and network delay compensator. The control prediction generator provides a set of future control predictions to make the closed-loop system achieve the desired control performance and the network delay compensator removes the effects of the network transmission delay and data dropout. Sufficient conditions are given for the closed-loop networked predictive control system to be stochastically stable with noise attenuation level gamma

Sliding Mode Control for Stochastic Jump Systems with Time-Delay

Abstract: The problems of stochastic stability and sliding mode control for a class of linear time-delay systems with stochastic jumps are considered in this paper. The jumping parameters appeared in the system matrices are modelled as a continuous-time, discrete-state homogeneous Markov process with right continuous trajectories taking values in a finite set. Sufficient conditions are proposed to guarantee the stochastic stability of the underlying system based on linear matrix inequalities (LMI) approach. Then, a reaching motion controller is designed such that the resulting closed-loop system can be driven onto the desired sliding surface in finite time. It has been shown that the sliding mode control problem for the Markovian jump systems is solvable if a set of coupled linear matrix inequalities (LMIs) have solutions.

Robust stabilization of a class of nonlinear networked control systems

Abstract: This paper is concerned with the robust stabilization problem for a class of networked control systems with nonlinear perturbations. The perturbations are assumed to be time-varying and satisfying quadratic constraints. Such networked control systems are modeled as systems with time-varying delays. Based on this model, observer-based controllers are designed to stabilize the nonlinear systems subject to the network-induced delay and data dropout. Sufficient conditions on existences of the stabilizing controllers are established. The controller gains can be obtained by solving a set of linear matrix inequalities. An illustrative example is given to demonstrate the effectiveness of the proposed method.

Development of Networked Robot Fish Control Systems

Abstract: In this paper, a networked control system based on Simulink's s-function is presented for remote control of a biomimetic robot fish. The whole system consists of a network camera, a remote controller, a local controller and a robot fish. The remote controller obtains real-time images from the network camera, processes these images, generates control instructions, and sends the control instructions to the robot fish through a network. The local controller receives the instructions and sends them to the robot fish via wireless communication. The control system on the remote computer is developed as a Simulink model with s-function modules, in which an image processing algorithm and a rule-based control algorithm proposed are realized. The experimental results for point-to-point motion control of a robot fish through intra-net are given.

Output Feedback Control of Discrete Systems with Time-Varying Delay

Abstract: In this paper, the problem of output feedback control of discrete systems with time-varying delay is presented. A new method is proposed to design static feedback controller for systems with time-varying delays. The resulted closed-loop systems are switching systems, then the static control gain can be obtained based on linear matrix inequality (LMI). Furthermore, the results can be extended to design output feedback control of discrete time-varying systems

Design and Realization of Motor Control System Based on Stateflow and Ethernet

Abstract: This paper describes modeling and realization of brushless DC motor speed control system. Firstly a control logic model is built using stateflow chart, which provides auto/manual bumpless switch function. Then the chart is integrated into Simulink to attain complete controller model. Finally the practical engineering realization of control system is presented based on Ethernet (Internet) communication. Using NetCon system, the complete process from system design to realization can be finished quickly and engineering applications can be built easily. The motor control example illustrates the feasibility of design and the efficiency of implementation and it can be applied to other similar control systems.

Improvement on Security of a Practical Solution to Remote Authentication

Abstract: Chien, Jan, and Tseng proposed a practical solution to remote authentication using smart cards in 2002. This scheme is efficient and provides mutual authentication between the user and the server. In this paper a security breach is shown to exist in Chien-Jan-Tseng scheme; an intruder can easily impersonate a legal user to login the remote server or impersonate the server to cheat the user. A nonce-based scheme is put forward to preclude these potential attacks. Also the improved solution can avoid the replay attacks of the user's login message and the server's authentication message

Subcooled pool boiling on thin wire in microgravity

Abstract: A new set of experimental data of subcooled pool boiling on a thin wire in rnicrogravity aboard the 22nd Chinese recoverable satellite is reported in the present paper The temperature-control led heating method is used The results of the experiments in normal gravity before and after the flight experiment are also presented, and compared with those in microgravity The working fluid is degassed R113 at 01 MPa and subcooled by 26 degrees C nominally A thin platinum wire of 60 mu m in diameter and 30 mm in length is simultaneously used as heater and thermometer It is found that the heat transfer of nucleate pool boiling is slightly enhanced in microgravity comparing with those in normal gravity It is also found that the correlation of Lienhard and Dhir can predict the CHF with good agreement, although the range of the dimensionless radius is extended by three or more decades above the originally set limit Three critical bubble diameters are observed in microgravity, which divide the observed vapor bubbles into four regimes with different sizes Considering the Marangoni effect, a qualitative model is proposed to reveal the mechanism underlying the bubble departure processes, and a quantitative agreement can also be acquired