Huifeng Zhang

Composite disturbance-observer-based control and terminal sliding mode control for uncertain structural systems

A new type of composite control scheme of disturbance-observer-based control and terminal sliding mode control (TSMC) is proposed for uncertain structural systems. The disturbance are supposed to include two parts. One is generated by an exogenous system, which can represent the harmonic signals with modelling perturbations in structural system. The other part is external excitation in H 2-norm context. The disturbance observers based on regional pole placement and D-stability theory are presented, which can be designed separately from the controller design. By integrating the disturbance observer with TSMC law, the disturbance with the exogenous system can be estimated and compensated, and external excitation can be attenuated in finite time. Finally, simulations for a four-degree-of-freedom building model excited by 1940 El Centro earthquake excitation are given to demonstrate the effectiveness of the approach and compare the proposed results with the previous schemes with accuracy.

Composite disturbance-observer-based control and variable structure control for non-linear systems with disturbances

A novel type of control scheme combining the disturbance-observer-based control (DOBC) with variable structure control (VSC) is proposed for a class of continuous non-linear systems subject to disturbances. The disturbances are supposed to include two parts. One in the input channel is generated by an exogenous system with uncertainty, which can represent the harmonic signals with modelling perturbations. The other is supposed to have the bounded H2 norm. The disturbance observers based on regional pole placement and D-stability theory are presented, which can be designed separately from the controller design. By integrating DOBC with VSC laws, the disturbances can be rejected and the desired dynamic performances can be guaranteed for continuous systems in finite time with known and unknown non-linear dynamics, respectively. Simulations for a flight control system are given to demonstrate the effectiveness of the results and compare the proposed results with the previous schemes.

Composite disturbance-observer-based control and terminal sliding mode control for complex models

A novel type of control scheme combined the distance-observer-based control (DOBC) with terminal sliding mode control is proposed for a class of continuous complex models subject to disturbances. The disturbances are supposed to include two parts. One in the input channel is generated by an exogenous system with uncertainty, which can represent the harmonic signals with modeling perturbations. The other is supposed to have the bounded H2 norm. The disturbance observers based on regional pole placement and D-stability theory are presented, which can be designed separately from the controller design. By integrating DOBC with terminal sliding mode control laws, the disturbances can be rejected and the desired dynamic performances can be guaranteed for complex systems with known and unknown nonlinear dynamics, respectively. Simulations for a flight control system are given to demonstrate the effectiveness of the results and compare the proposed results with the previous schemes.

Composite Disturbance-Observer-Based Control and Terminal Sliding Mode Control for Uncertain Structural Systems

Abstract A new type of composite control scheme of disturbance-observer-based control and terminal sliding mode control is proposed for uncertain structural systems. The disturbance are supposed to include two parts. One is generated by an exogenous system, which can represent the harmonic signals with modeling perturbations in structural system. The other part is external excitation in H 2 -norm context. By combining the disturbance observer with terminal sliding mode control law, the disturbance with the exogenous system can be estimated and compensated, and external excitation can be attenuated in finite time which can be computed by our approach. Especially, the design of disturbance observer and controller can be obtained separately. Finally, simulations for a four-degree-of-freedom building model excited by 1940 El Centro earthquake excitation are given to demonstrate the effectiveness of the approach and compare the proposed results with the previous schemes in accuracy.

Disturbance rejection for nonlinear systems with mismatched disturbances based on disturbance observer

Abstract A disturbance rejection approach based on disturbance observer is proposed for a class of nonlinear systems subject to mismatched disturbances. The mismatched disturbances are described by exogenous systems and satisfy partially-known information, which enter the system in the different channels with the control input. The disturbance observer is designed to estimate the mismatched disturbances, which can be introduced separately from the controller design. By integrating disturbance observer with back-stepping method, the disturbance observer plus back-stepping (DOPBS) controller can be constructed to reject the mismatched disturbances. And the asymptotically stability for the closed-loop system can be achieved. Finally, simulation examples are given to demonstrate the feasibility and effectiveness of the proposed scheme compared with existing methods.

Anti-disturbance control based on disturbance observer for nonlinear systems with bounded disturbances

Abstract A composite anti-disturbance control problem for a class of nonlinear systems is studied in this paper. There are two types of disturbances in the systems, one is the matched disturbance with bounded variation rate, the other is the unmatched time-varying disturbances. A nonlinear disturbance observer is designed to estimate the matched disturbances, which can be presented separately from the controller design. By integrating DOBC with back-stepping method, a composite DOBC and back-stepping controller is proposed, and the disturbance estimations are introduced into the design of virtual control laws to compensate the unmatched disturbances. In addition, it is proved that all the states in the closed-loop system are uniformly ultimate bounded (UUB). Finally, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed method.

Chaos Synchronization of General Complex Dynamical Networks with Coupling Delays

Many real-world dynamical networks display the feature of complex structure, and the complexity feature of networks has attracted increasing attention from various fields of science and engineering. In this paper, we introduce a general dynamical network with different coupling strength and study the complexity of this network model with time delays. Based on the theories of linear matrix inequalities (LMI), the asymptotical stabilities of the network chaos synchronization for delay-dependent are investigated. We finally use a dynamical chaos network with time delay and specific coupling scheme as an example to illustrate the theoretical results.

Anti-disturbance control based on nonlinear disturbance observer for a class of stochastic systems

In engineering, there exist lots of nonlinear disturbance dynamics, which can be described by nonlinear exogenous systems. The current stochastic linear disturbance observer is conservative and is not applicable for nonlinear disturbance dynamics. This paper studies a class of stochastic systems with multiple disturbances, including white noise and disturbances modelled by a nonlinear exogenous system. To estimate the disturbance with nonlinear dynamics, a stochastic nonlinear disturbance observer is proposed. Based on the observer, a nonlinear disturbance observer-based disturbance attenuation control (NDOBDAC) scheme is constructed such that the composite closed-loop system is asymptotically mean-square bounded. According to the simulation example, the state responses of the system diverge in the absence of control, but it tends to be ± 0 . 01 under NDOBDAC, which demonstrates the effectiveness of the proposed scheme. In addition, the anti-disturbance control accuracy of NDOBDAC approximately improves 60 ~ 200 times compared with H ∞ control and active disturbance rejection control (ADRC). The simulation results demonstrate the feasibility and effectiveness of the proposed scheme.

Composite hierarchical anti-disturbance control for stochastic systems with multiple disturbances

A class of stochastic systems with multiple disturbances, which includes white noises and disturbances whose time derivative is bounded, is considered in this paper. To estimate the unknown bounded disturbance, a stochastic disturbance observer is proposed. Based on the observer, a disturbance observer-based disturbance control scheme is constructed such that the composite closed-loop system is asymptotically bounded. Finally, a simulation example is given to demonstrate the feasibility and effectiveness of the proposed scheme.

Composite fault-tolerant control with disturbance observer for stochastic systems with multiple disturbances

Abstract In this paper, a composite fault tolerant control (CFTC) with disturbance observer scheme is considered for a class of stochastic systems with faults and multiple disturbances. The disturbances are divided into two parts. One represents the stochastic disturbance with partial known information which is formulated by an exogenous system. The other is independent Wiener process. A stochastic disturbance observer is designed to estimate exogenous disturbance. To make the first type of disturbance can be rejected and the fault can be diagnosed, a composite fault diagnosis observer with disturbance observer is constructed. Furthermore, a composite fault-tolerant controller is proposed to compensate disturbances and faults. Finally, simulation examples are given to demonstrate the feasibility and effectiveness of the proposed scheme.