Shi Song-jiao

Robust fault diagnosis for linear time-delay systems with uncertainty

This paper deals with the problem of fault diagnosis problem for a class of linear systems with delayed state and uncertainty. The systems are transformed into two different subsystems. One is not affected by actuator faults so that a robust observer can be designed under certain conditions. The other whose states can be measured is affected by the faults. The proposed observer is utilized in an analytical-redundancy-based approach for actuator and sensor fault detection and diagnosis in time-delay systems. Finally, the applicability and effectiveness of the proposed method is illustrated through numerical examples.

Design of H∞ robust fault detection filter for nonlinear time-delay systems

In this paper, the robust fault detection filter (RFDF) design problems are studied for nonlinear time-delay systems with unknown inputs. First, a reference residual model is introduced to formulate the RFDF design problem as an H∞ model-matching problem. Then appropriate input/output selection matrices are introduced to extend a performance index to the time-delay systems in time domain. The reference residual model designed according to the performance index is an optimal residual generator, which takes into account the robustness against disturbances and sensitivity to faults simultaneously. Applying robust H∞ optimization control technique, the existence conditions of the RFDF for nonlinear time-delay systems with unknown inputs are presented in terms of linear matrix inequality (LMI) formulation, independently of time delay. An illustrative design example is used to demonstrate the validity and applicability of the proposed approach.

Model identification and PID control of long time-delay processes

A relay feedback identification auto-tuning of PID/PI controller is proposed in this paper, which is capable of controlling long time-delay processes. The real process is approximated via FOPDT or SOPDT models, whose parameters are specified through a modified relay feedback identification method. Applying the zero-pole cancellation principle, the PID/PI controller is tuned according to the specified amplitude and phase margins. Model identification and controller parameter tuning are done online without much influence on the normal operation. This algorithm also has many other advantages such as a fast setpoint response, strong robustness and good disturbance rejection ability.

A novel Smith predictor with double-controller structure

Aiming at the disadvantage of the conventional Smith predictor with weak robustness, a novel one with double-controller is proposed in this paper. It has a two-degree of freedom structure so that the setpoint response is decoupled from the disturbance response. Thus, the setpoint tracking and disturbance attenuation controllers can be designed separately. At the same time, the two controllers are all designed into PID structures whose parameters can be adjusted by a parameter, respectively, so that the corresponding response tends to be optimal.

AUTOTUNING PID CONTROL FOR LONG TIME-DELAY PROCESSES

Abstract A refined relay feedback identification autotuning PID/PI is proposed in this paper which is capable of controlling long time-delay processes. The process is approximated via FOPDT or SOPDT models, whose parameters are determined through a modified relay feedback identification method. Employing zero-pole cancellation principle, the PID/PI is tuned by the specified amplitude and phase margins, which can guarantee fast response and strong robustness to the closed loop system. Model identification and controller parameter tuning are done on-line without much influence on the normal operation. In addition, this algorithm also has good disturbance rejection capability.

An Active Fault Tolerant Controller Design Method for Time-delay Systems

In this paper, we propose an active fault tolerant control (FTC) design method for time-delay systems. Based on generalized internal model control (GIMC), the feedback controller architecture includes two parts: one part for performance and the other part for robustness. The feedback control system will be solely controlled by the performance controller when there is no fault and the robustification controller will be active when there are faults.

Synchronization of coupled dynamical chaotic networks via scalar controllers

Some scalar linear controllers, which can ensure that the states of coupled chaotic dynamical networks asymptotically synchronize each other, are derived on the basis of high gain state feedback control. Numerical simulation is given to validate the proposed theoretical result.

Global synchronization of Chua＇s chaotic delay network by using linear matrix inequality

Global synchronization of Chuas chaotic dynamical networks with coupling delays is investigated in this paper. Unlike other approaches, where only local results were obtained, the network is found to be not linearized in this paper. Instead, the global synchronization is obtained by using the linear matrix inequality theory. Moreover, some quite simple linear-state-error feedback controllers for global synchronization are derived, which can be easily constructed based on the minimum eigenvalue of the coupling matrix. A simulation of Chuas chaotic network with global coupling delays in nodes is finally given, which is used to verify the theoretical results of the proposed global synchronization scheme.

Robust adaptive output-feedback control of a class of uncertain nonlinear systems

Abstract With an attempt to simplify the controller design and to reduce the control effort, a new robust output-feedback controller is designed to solve the tracking problem of a class of nonlinear uncertain systems by using observer plus backstepping. In the controller design, a simple observer is constructed, by which only a coarse estimate of the unknown states is provided, and a positive function used to generate a new normalization signal and the positive nonlinear functions used in nonlinear damping terms are all left to be chosen freely. Thanks to these techniques, the new controller can be designed with a simpler structure and reduced control effort under weaker assumptions on both the uncertainties and the reference signal. The global boundness of all closed-loop signals can be guaranteed, and the output tracking error can be made as small as possible

On the Well-posedness of the PWM Control System

One of the basic issues in the study of hybrid systems is the well-posedness (existence and uniqueness of solutions) problem of discontinuous dynamical systems. This paper addresses this problem for a class of piecewise affine discontinuous systems with affine inequalities such as systems with pulse-width modulator under the definition of Carathéodory solutions in terms of an analysis based on lexicographic inequalities and the smooth continuation property of solutions. Furthermore, it is clear that when carrier signal h(t)=0, closed-loop pulse-width modulation (PWM) DC-DC converters are not well posed, and when some condition is satisfied, the closed-loop PWM DC-DC converters with a P controller are well posed.