This paper focuses on the H∞ controller design for linear systems with time-varying delays and norm-bounded parameter perturbations in the system state and control/disturbance. On the existence of delayed/undelayed f...This paper focuses on the H∞ controller design for linear systems with time-varying delays and norm-bounded parameter perturbations in the system state and control/disturbance. On the existence of delayed/undelayed full state feedback controllers, we present a sufficient condition and give a design method in the form of Riccati equation. The controller can not only stabilize the time-delay system, but also make the H∞ norm of the closed-loop system be less than a given bound. This result practically generalizes the related results in current literature.展开更多
As saturation is involved in the stabilizing feedback control of a linear discrete-time system, the original global-asymptotic stabilization (GAS) may drop to region-asymptotic stabilization (RAS). How to test if the ...As saturation is involved in the stabilizing feedback control of a linear discrete-time system, the original global-asymptotic stabilization (GAS) may drop to region-asymptotic stabilization (RAS). How to test if the saturated feedback system is GAS or RAS? The paper presents a criterion to answer this question, and describes an algorithm to calculate an invariant attractive ellipsoid for the RAS case. At last, the effectiveness of the approach is shown with examples.展开更多
New idea of stabilization for discrete linear multiple-input system is proposed based on switching technique and single-input control. The system discussed here denotes coupled singleinput objects to be controlled. Th...New idea of stabilization for discrete linear multiple-input system is proposed based on switching technique and single-input control. The system discussed here denotes coupled singleinput objects to be controlled. The central processing unit chooses an object at each discrete instant according to periodic switching strategy and controls it by local state feedback. Stabilization of a multiple-input system is turned into stabilization of single-input systems under periodic switching strategy, which is easy to be realized in practice. On the other hand, only one central processing unit can realize all local controllers, which decreases the cost and increases the usage of the resources.展开更多
This paper examines the delay-dependent H-infinity control problem for discrete-time linear systems with time-varying state delays and norm-bounded uncertainties. A new inequality for the finite sum of quadratic terms...This paper examines the delay-dependent H-infinity control problem for discrete-time linear systems with time-varying state delays and norm-bounded uncertainties. A new inequality for the finite sum of quadratic terms is first established. Then, some new delay-dependent criteria are derived by employing the new inequality to guarantee the robust stability of a closed-loop system with a prescribed H-infinity norm bound for all admissible uncertainties and bounded time-vary delays. A numerical example demonstrates that the proposed method is an improvement over existing ones.展开更多
This paper investigates the problem of robust optimal H<sub>∞</sub> control for uncertain two-dimensional (2-D) discrete state-delayed systems described by the general model (GM) with norm-bounded uncerta...This paper investigates the problem of robust optimal H<sub>∞</sub> control for uncertain two-dimensional (2-D) discrete state-delayed systems described by the general model (GM) with norm-bounded uncertainties. A sufficient condition for the existence of g-suboptimal robust H<sub><sub></sub></sub><sub>∞</sub> state feedback controllers is established, based on linear matrix inequality (LMI) approach. Moreover, a convex optimization problem is developed to design a robust optimal state feedback controller which minimizes the H<sub><sub><sub></sub></sub></sub><sub>∞</sub> noise attenuation level of the resulting closed-loop system. Finally, two illustrative examples are given to demonstrate the effectiveness of the proposed method.展开更多
Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness t...Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness test of aircraft actuation systems. The tracking performance of the static loading is studied in this paper. Firstly, the nonlinear mathematical models of the hydraulic load simulator are derived, and the feedback linearization method is employed to construct a feed-forward controller to improve the force tracking performance. Considering the effect of the friction, a LuGre model based friction compensation is synthesized, in which the unmeasurable state is estimated by a dual state observer via a controlled learning mechanism to guarantee that the estimation is bounded. The modeling errors are attenuated by a well-designed robust controller with a control accuracy measured by a design parameter. Employing the dual state observer is to capture the different effects of the unmeasured state and hence can improve the friction compensation accuracy. The tracking performance is summarized by a derived theorem. Experimental results are also obtained to verify the high performance nature of the proposed control strategy.展开更多
This paper discusses H-infinity state feedback control for a networked control system with time-varying delays. Based on the flee-weighing matrix method, a dehy-dependent stability criterion satisfying a prescribed H-...This paper discusses H-infinity state feedback control for a networked control system with time-varying delays. Based on the flee-weighing matrix method, a dehy-dependent stability criterion satisfying a prescribed H-infinity norm bound is presented for an NCS with unknown, time-varying and bounded delays. And then, the criterion is transformed into sufficient conditions based on linear matrix inequalities for H-infinity control. The conditions thus obtained are also used to design an H-infinity state feedback controller. This design method is further extended to solve the design problem of robust H-infinity state feedback control. A numerical example demonstrates the validity of the method.展开更多
The exist researches of the magneto-rheological semi-active suspension(MSAS) control mainly focus on the design of control laws,which aim at obtaining an optimal control strategy to improve the ride comfort and handli...The exist researches of the magneto-rheological semi-active suspension(MSAS) control mainly focus on the design of control laws,which aim at obtaining an optimal control strategy to improve the ride comfort and handling stability.In the controller design,the stability of the MSAS system cannot be confirmed owing to the control input time delay considered little.In this paper,a quarter vehicle MSAS model with time-delay is built.Therefore,through formulating the sprung mass acceleration suitably as the optimization object,suspension deflection and tyre dynamic load and coulomb damping force as the constraint objects,with considering the control input time-delay,a delay-dependent state feedback H2/H∞ controller is designed.According to Lyapunov-Krasovskii functional theory,the sufficient conditions for asymptotic stability and the existence of delay-dependent H2/H∞ controller are obtained,and the controller design is transformed into the minimization problem for linear function through linear matrix inequality(LMI).Random road excitation simulations and experiments are carried out.The simulation and experiment results show that the design can preserve the closed-loop stability and achieve the performances for MSAS system in spite of the existence of the control input time-delay.The present study can provide an important basis and method for research on time-delay problem in MSAS and other chassis subsystems.展开更多
A procedure for the design of state feedback controller for seismic-excited structures is presented in this paper.The external exciting-controlled structure-control system was simulated using state space model.Based o...A procedure for the design of state feedback controller for seismic-excited structures is presented in this paper.The external exciting-controlled structure-control system was simulated using state space model.Based on the convex optimization technology and variance control theorem,the general expression of linear matrix inequalities (LMIs) for state feedback controller with closed-loop poles and the steady variance responses constrained were deduced,in which the poles and variance response of system were guaranteed to satisfy certain constraints assigned in advance.LMI Toolbox of MATALB was employed for optimizing the state feedback controller.At last,a three-story simple lumped mass shear model was used to demonstrate the effectiveness and superiority of the proposed method.展开更多
In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as t...In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as the penetration level of wind power generation increases, the low inertia and lack of synchronous power characteristics of the penetrated power system can have a significant impact on the transient stability of the grid. The virtual synchronous generator provides the ability of virtual inertia and synchronous power to interconnected inverters. The interconnected inverter with the virtual synchronous generator ability uses, in general, PI control based current controller. This paper proposes a new current-control method and compares it with conventional methods. The proposed current control is a method that follows virtual synchronous generator model that changes every moment by solving the discrete-time linear quadratic optimal control problem for each sampling time interval. The new method follows the conventional method, and therefore the reactive power fluctuation can be suppressed and the interconnected inverter will be downsized.展开更多
In this paper, fixed-order l1-control for systems with time-delay is studied, and sufficient conditions for solvability of state-feedback l1-control and dynamic output-feedback l1-control are obtained. This paper also...In this paper, fixed-order l1-control for systems with time-delay is studied, and sufficient conditions for solvability of state-feedback l1-control and dynamic output-feedback l1-control are obtained. This paper also gives the forms of solution to l1-controller. In the paper, the problem is not cast into infinite dimensional constrained convex optimal problem, but an upper bound of l1-norm is optimized. Although the l1-control is sub-optimal, the analysis and design are simple. The result of the paper improves and develops the l1-control method.展开更多
基金This project was supported by the National Natural Science Foundation of China (No. 69974022).
文摘This paper focuses on the H∞ controller design for linear systems with time-varying delays and norm-bounded parameter perturbations in the system state and control/disturbance. On the existence of delayed/undelayed full state feedback controllers, we present a sufficient condition and give a design method in the form of Riccati equation. The controller can not only stabilize the time-delay system, but also make the H∞ norm of the closed-loop system be less than a given bound. This result practically generalizes the related results in current literature.
基金Supported by National Natural Science Foundation of P. R. China (60174040)
文摘As saturation is involved in the stabilizing feedback control of a linear discrete-time system, the original global-asymptotic stabilization (GAS) may drop to region-asymptotic stabilization (RAS). How to test if the saturated feedback system is GAS or RAS? The paper presents a criterion to answer this question, and describes an algorithm to calculate an invariant attractive ellipsoid for the RAS case. At last, the effectiveness of the approach is shown with examples.
基金Supported by National Natural Science Foundation of P. R. China (60274009 and 69934010)Specialized Research Fund for the Doctoral Program of Higher Education (20020145007)Doctoral Foundation of P. R. China (2003033500)Technological Foundation of Southeast University (9802001472)
文摘New idea of stabilization for discrete linear multiple-input system is proposed based on switching technique and single-input control. The system discussed here denotes coupled singleinput objects to be controlled. The central processing unit chooses an object at each discrete instant according to periodic switching strategy and controls it by local state feedback. Stabilization of a multiple-input system is turned into stabilization of single-input systems under periodic switching strategy, which is easy to be realized in practice. On the other hand, only one central processing unit can realize all local controllers, which decreases the cost and increases the usage of the resources.
基金This work was partially supported by the National Science Foundation of China (No. 60425310, 60574014), the Doctor Subject Foundation of China(No. 20050533015) and the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of the Ministryof Education, P. R. China (TRAPOYT).
文摘This paper examines the delay-dependent H-infinity control problem for discrete-time linear systems with time-varying state delays and norm-bounded uncertainties. A new inequality for the finite sum of quadratic terms is first established. Then, some new delay-dependent criteria are derived by employing the new inequality to guarantee the robust stability of a closed-loop system with a prescribed H-infinity norm bound for all admissible uncertainties and bounded time-vary delays. A numerical example demonstrates that the proposed method is an improvement over existing ones.
文摘This paper investigates the problem of robust optimal H<sub>∞</sub> control for uncertain two-dimensional (2-D) discrete state-delayed systems described by the general model (GM) with norm-bounded uncertainties. A sufficient condition for the existence of g-suboptimal robust H<sub><sub></sub></sub><sub>∞</sub> state feedback controllers is established, based on linear matrix inequality (LMI) approach. Moreover, a convex optimization problem is developed to design a robust optimal state feedback controller which minimizes the H<sub><sub><sub></sub></sub></sub><sub>∞</sub> noise attenuation level of the resulting closed-loop system. Finally, two illustrative examples are given to demonstrate the effectiveness of the proposed method.
基金National Science Fund for Distinguished Young Scholars (50825502)
文摘Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness test of aircraft actuation systems. The tracking performance of the static loading is studied in this paper. Firstly, the nonlinear mathematical models of the hydraulic load simulator are derived, and the feedback linearization method is employed to construct a feed-forward controller to improve the force tracking performance. Considering the effect of the friction, a LuGre model based friction compensation is synthesized, in which the unmeasurable state is estimated by a dual state observer via a controlled learning mechanism to guarantee that the estimation is bounded. The modeling errors are attenuated by a well-designed robust controller with a control accuracy measured by a design parameter. Employing the dual state observer is to capture the different effects of the unmeasured state and hence can improve the friction compensation accuracy. The tracking performance is summarized by a derived theorem. Experimental results are also obtained to verify the high performance nature of the proposed control strategy.
文摘This paper discusses H-infinity state feedback control for a networked control system with time-varying delays. Based on the flee-weighing matrix method, a dehy-dependent stability criterion satisfying a prescribed H-infinity norm bound is presented for an NCS with unknown, time-varying and bounded delays. And then, the criterion is transformed into sufficient conditions based on linear matrix inequalities for H-infinity control. The conditions thus obtained are also used to design an H-infinity state feedback controller. This design method is further extended to solve the design problem of robust H-infinity state feedback control. A numerical example demonstrates the validity of the method.
基金supported by National Natural Science Foundation of China (Grant No. 51075112,Grant No. 51175135)
文摘The exist researches of the magneto-rheological semi-active suspension(MSAS) control mainly focus on the design of control laws,which aim at obtaining an optimal control strategy to improve the ride comfort and handling stability.In the controller design,the stability of the MSAS system cannot be confirmed owing to the control input time delay considered little.In this paper,a quarter vehicle MSAS model with time-delay is built.Therefore,through formulating the sprung mass acceleration suitably as the optimization object,suspension deflection and tyre dynamic load and coulomb damping force as the constraint objects,with considering the control input time-delay,a delay-dependent state feedback H2/H∞ controller is designed.According to Lyapunov-Krasovskii functional theory,the sufficient conditions for asymptotic stability and the existence of delay-dependent H2/H∞ controller are obtained,and the controller design is transformed into the minimization problem for linear function through linear matrix inequality(LMI).Random road excitation simulations and experiments are carried out.The simulation and experiment results show that the design can preserve the closed-loop stability and achieve the performances for MSAS system in spite of the existence of the control input time-delay.The present study can provide an important basis and method for research on time-delay problem in MSAS and other chassis subsystems.
基金Supported by National Natural Science Foundation of China (Grant No. 50608021,90815027)
文摘A procedure for the design of state feedback controller for seismic-excited structures is presented in this paper.The external exciting-controlled structure-control system was simulated using state space model.Based on the convex optimization technology and variance control theorem,the general expression of linear matrix inequalities (LMIs) for state feedback controller with closed-loop poles and the steady variance responses constrained were deduced,in which the poles and variance response of system were guaranteed to satisfy certain constraints assigned in advance.LMI Toolbox of MATALB was employed for optimizing the state feedback controller.At last,a three-story simple lumped mass shear model was used to demonstrate the effectiveness and superiority of the proposed method.
文摘In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as the penetration level of wind power generation increases, the low inertia and lack of synchronous power characteristics of the penetrated power system can have a significant impact on the transient stability of the grid. The virtual synchronous generator provides the ability of virtual inertia and synchronous power to interconnected inverters. The interconnected inverter with the virtual synchronous generator ability uses, in general, PI control based current controller. This paper proposes a new current-control method and compares it with conventional methods. The proposed current control is a method that follows virtual synchronous generator model that changes every moment by solving the discrete-time linear quadratic optimal control problem for each sampling time interval. The new method follows the conventional method, and therefore the reactive power fluctuation can be suppressed and the interconnected inverter will be downsized.
文摘In this paper, fixed-order l1-control for systems with time-delay is studied, and sufficient conditions for solvability of state-feedback l1-control and dynamic output-feedback l1-control are obtained. This paper also gives the forms of solution to l1-controller. In the paper, the problem is not cast into infinite dimensional constrained convex optimal problem, but an upper bound of l1-norm is optimized. Although the l1-control is sub-optimal, the analysis and design are simple. The result of the paper improves and develops the l1-control method.
