Fenghuang Cai

Observer-based robust reliable H ∞ control for uncertain time-delay discrete-time systems in the presence of sensor failure

The reliable Hinfin control problem for time-varying delayed discrete-time systems is proposed for the case of a simultaneous presence of sensor failures. A more practical general mode of sensor is presented to investigate sensor failures. Based on a linear matrix inequality (LMI) technique, an observer-based reliable controller is designed, such that, both in normal and fault cases of sensor, the closed-loop system is asymptotically stable and has an Hinfin disturbance attenuation boundness. A numerical example is presented to demonstrate the applicability and effectiveness of the proposed approach.

l 2 -l ∞ output feedback control for a class of networked system with random delay

This paper investigates the problem of output feedback l2-l∞ control for networked system with random delays. The sensor-to-controller and controller-to-actuator delays are simultaneously considered due to limited bandwidth communication. The random delays are described by a binary switching sequence satisfying a Bernoulli distribution. The purpose is the design of a dynamic output feedback controller which ensures the exponentially mean-square stability of the closed-loop system and guarantees an l2-l∞ norm bound constraint on disturbance attenuation. Via matrix inequalities a sufficient condition for solvability of this problem is presented. The sequentially linear programming method (SLPMM) is applied to solve the matrix inequalities. A numerical example is provided to demonstrate the validity of the proposed design approach.

Control Strategy Design of Grid-Connected and Stand-Alone Single-Phase Inverter for Distributed Generation

Dual-mode photovoltaic power system should be capable of operating in grid-connected (GC) and stand-alone (SA) modes for distributed generation. Under different working modes, the optimal parameters of inverter output filters vary. Inverters commonly operate in GC mode, and thus, a small capacitance is beneficial to the GC topology for achieving a reasonable compromise. A predictive current control scheme is proposed to control the grid current in GC mode and thereby obtain high-performance power. As filter are not optimal under SA mode, a compound control strategy consisting of predictive current control, instantaneous voltage control, and repetitive control is proposed to achieve low total harmonic distortion and improve the output voltage spectrum. The seamless transfer between GC mode and SA mode is illustrated in detail. Finally, the simulation and experimental results of a 4 ㎸A prototype demonstrate the effectiveness of the proposed control strategy.

An H 2 approach for networked control systems with multiple packet dropouts

In this technical note, an H2 approach to network-based control system with multiple packet dropouts is introduced. The communication links over network media are assumed to be data-packet dropouts. Two channel packet dropouts are simultaneously considered due to limited communication capacity and unreliable communication links. One is measurement channel packet dropouts which are from the sensor to the controller. The other is control channel packet dropouts which are from the controller to the actuator. Stochastic variables satisfying the Bernoulli random binary distribution are utilized to model the random multiple packet dropouts. A linear matrix inequality(LMI)-based design method is proposed for designing observer-based feedback H2 controller to guarantee the closed-loop networked control system to be asymptotically mean-square stable and preserve a guaranteed H2 performance. Finally, an illustrative example is provided to show the applicability of the proposed method.

Fault detection for networked switched systems with random communication delays

Under the condition of random communication delays, this paper deals with the problem of fault detection for networked switched systems with arbitrary switching laws. The delay of data packets include the measured output and the switched signal and the delays satisfy the Bernoulli random binary distribution. By using multiple Lyapunov function, a general observer-based fault detection filter is designed and applied as the residual generation system. Then the design of fault detection filter is formulated as H∞ filtering problem in terms of H∞ theory. Sufficient condition for the existence of the filter is established by means of linear matrix inequalities (LMI) at last. A numerical example shows the validity of the proposed method.

Dissipative control for networked nonlinear system with random delay

This paper focuses on problem of quadratic dissipative control for networked nonlinear system with random delay. The T-S discrete fuzzy model system is adopted for modeling the nonlinear system. The dynamic output feedback controller is to be designed. Random delays from the sensor to the controller and from the controller to the actuator are simultaneously considered. And the random delays are described by a binary switching sequence satisfying a Bernoulli distribution. Sufficient conditions for existence of a dynamic output feedback fuzzy controller, such that the closed-loop system is exponentially mean-square stable and strict quadratic dissipative, is present via matrix inequality method. The iterative algorithm is provided to solve the matrix inequalities by using SLPMM (sequentially linear programming matrix method). Finally, a numerical example is given to show the validity and feasibility of the proposed approach.

Mixed H 2 /H ∞ control for networked control system with missing data

In the framework of multi-objective control, this paper presents a mixed H2/Hinfin dynamic output feedback control strategy to the network remote control system with measurement data missing and control data missing. Via matrix inequality method, the sufficient for existence of the dynamic output feedback controller, guaranteeing the closed-loop system has H2 and Hinfin performance simultaneously, is given. A novel arithmetic is put forward to optimize the controller performance via SLPMM (sequentially linear programming matrix method). A numerical example is presented to demonstrate the feasibility of the proposed design approach.

Observer-based H ∞ control for linear stochastic discrete-time systems with missing measurements

This paper deals with the problem of state observer-based Hinfin state feedback design for linear stochastic discrete-time systems with missing measurements based on a method of linear matrix inequality (LMI). Criteria for the existence and design method of the state observers and state feedback controllers are derived. The numerical example shows the feasibility of the proposed controllers design procedure.

Fuzzy Iterative Learning Control for Nonlinear Systems with Missing Data

For packet-based transmission of data over a network, or temporary sensor failure, etc., data samples may be missing in the measured signals. The missing measurements will happen at any sample time, and the probability of the occurrence of missing data was assumed to be known. The series which fulfils Bernoulli distribution was used to describe the missing measurements. Based on the Takagi-Sugeno fuzzy model, nonlinear system was represent by T-S fuzzy model via the so-called parallel distributed compensation (PDC) approach. The fuzzy iterative learning controller was developed to guarantee the expected convergence of the tracking error and with quadratic performance index. A numerical example was provided to demonstrate the validity of the proposed design approach