Roll motion of ships can be distinguished in two parts:an unavoidable part due to their natural movement while turning and an unwanted and avoidable part that is due to encounter with waves and rough seas in general.F...Roll motion of ships can be distinguished in two parts:an unavoidable part due to their natural movement while turning and an unwanted and avoidable part that is due to encounter with waves and rough seas in general.For the attenuation of the unwanted part of roll motion,ways have been developed such as addition of controllable fins and changes in shape.This paper investigates the effectiveness of augmenting the rudder used for rejecting part of the unwanted roll,while maintaining steering and course changing ability.For this purpose,a controller is designed,which acts through intentional superposition of fast,compared with course change,movements of rudder,in order to attenuate the high-frequency roll effects from encountering rough seas.The results obtained by simulation to exogenous disturbance support the conclusion that the roll stabilization for displacement can be effective at least when displacement hull vessels are considered.Moreover,robust stability and performance is verified for the proposed control scheme over the entire operating range of interest.展开更多
The time domain guideposts requirements of a pump-motor system is transfered into a series of constraints which express the robust performance upper bound and regional poles limits of the closed loop system. Then the ...The time domain guideposts requirements of a pump-motor system is transfered into a series of constraints which express the robust performance upper bound and regional poles limits of the closed loop system. Then the servo system control problem is transferred into the problem of robust performance optimizing under regional poles constrains described by linear matrix inequality (LMI). These LMIs are easy to solve through the Matlab LMI-toolbox. Simulations indicate that the controller has excellent dynamic, static and disturbance rejection performance, and the control system is robust and has perfect H2 performance to the bounded external torque disturbance.展开更多
A new semi-active suspension control strategy through mixed H2/H∞ robust technique was developed due to its flexibility and robustness to model uncertainties.A full car model with seven degrees of freedom was establi...A new semi-active suspension control strategy through mixed H2/H∞ robust technique was developed due to its flexibility and robustness to model uncertainties.A full car model with seven degrees of freedom was established to demonstrate the effectiveness of the new control approach.Magneto-rheological(MR) dampers were designed,manufactured and characterized as available semi-active actuators in the developed semi-active suspension system.The four independent mixed H2/H∞ controllers were devised in order to perform a distributed semi-active control system in the vehicle by which the response velocity and reliability can be improved significantly.The performance of the proposed new approach was investigated in time and frequency domains.A good balance between vehicle's comfort and road holding was achieved.An effective and practical control strategy for semi-active suspension system was thus obtained.This new approach exhibits some advantages in implementation,performance flexibility and robustness compared to existing methods.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
This paper is concerned with the H2 estimation and control problems for uncertain discretetime systems with norm-bounded parameter uncertainty. We first present an analysis result on H2 norm bound for a stable uncerta...This paper is concerned with the H2 estimation and control problems for uncertain discretetime systems with norm-bounded parameter uncertainty. We first present an analysis result on H2 norm bound for a stable uncertain system in terms of linear matrix inequalities (LMIs). A solution to the robust H2 estimation problem is then derived in terms of two LMIs. As compared to the existing results, our result on robust H2 estimation is more general. In addition, explicit search of appropriate scaling parameters is not needed as the optimization is convex in the scaling parameters. The LMI approach is also extended to solve the robust H2 control problem which has been difficult for the traditional Riccati equation approach since no separation principle has been known for uncertain systems. The design approach is demonstrated through a simple example.展开更多
This paper presents an improved method for H-two control with regional stability constraints for the closedloop system. The controller is given by the convex combination of a set of fixed gains. Both continuous and di...This paper presents an improved method for H-two control with regional stability constraints for the closedloop system. The controller is given by the convex combination of a set of fixed gains. Both continuous and discrete-time systems in a known polytopic domain are investigated. New LMI-based sufficient conditions for the existence of parameterdependent Lyapunov functions are proposed. Numerical examples are given to show the proposed conditions provide useful and less conservative results for the problems of H-two control with regional stability constraints.展开更多
A necessary maximum principle is given for nonzero-sum stochastic Oltterential games with random jumps. The result is applied to solve the H2/H∞ control problem of stochastic systems with random jumps. A necessary an...A necessary maximum principle is given for nonzero-sum stochastic Oltterential games with random jumps. The result is applied to solve the H2/H∞ control problem of stochastic systems with random jumps. A necessary and sufficient condition for the existence of a unique solution to the H2/H∞ control problem is derived. The resulting solution is given by the solution of an uncontrolled forward backward stochastic differential equation with random jumps.展开更多
The problem of H2 output feedback control for generalized system with structural uncertainties is studied using linear matrix inequality approach. A sufficient condition Of linear matrix inequality is presented such t...The problem of H2 output feedback control for generalized system with structural uncertainties is studied using linear matrix inequality approach. A sufficient condition Of linear matrix inequality is presented such that the closed-loop system is stable and satisfies H2 performance for all admissible uncertainties. Furthermore, the solution of the controller is given. An H2 output feedback controller is designed in the airborne dispenser pitch channel, and the simulation results show that the controller is effective.展开更多
Based upon the theory of the nonlinear quadric two-person nonzero-sum differential game,the fact that the time-limited mixed H2/H∞ control problem can be turned into the problem of solving the state feedback Nash bal...Based upon the theory of the nonlinear quadric two-person nonzero-sum differential game,the fact that the time-limited mixed H2/H∞ control problem can be turned into the problem of solving the state feedback Nash balance point is mentioned. Upon this,a theorem about the solution of the state feedback control is given,the Lyapunov stabilization of the nonlinear system under this control is proved,too. At the same time,this solution is used to design the nonlinear H2/H∞ guidance law of the relative motion between the missile and the target in three-dimensional(3D) space. By solving two coupled Hamilton-Jacobi partial differential inequalities(HJPDI),a control with more robust stabilities and more robust performances is obtained. With different H∞ performance indexes,the correlative weighting factors of the control are analytically designed. At last,simulations under different robust performance indexes and under different initial conditions and under the cases of intercepting different maneuvering targets are carried out. All results indicate that the designed law is valid.展开更多
The general discrete-time Single-Input Single-Output (SISO) mixed H2/l1 control problem is considered in this paper. It is found that the existing results of duality theory cannot be directly applied to this infinit...The general discrete-time Single-Input Single-Output (SISO) mixed H2/l1 control problem is considered in this paper. It is found that the existing results of duality theory cannot be directly applied to this infinite dimension optimisation problem. By means of two finite dimension approximate problems, to which duality theory can be applied, the dual of the mixed H2/l1 control problem is verified to be the limit of the duals of these two approximate problems.展开更多
This paper is concerned with the problem of designing robust H∞and H2static output feedback controllers for a class of discrete-time piecewise-affine singular systems with norm-bounded time-varying parameters uncerta...This paper is concerned with the problem of designing robust H∞and H2static output feedback controllers for a class of discrete-time piecewise-affine singular systems with norm-bounded time-varying parameters uncertainties. Based on a piecewise singular Lyapunov function combined with S-procedure,Projection lemma and some matrix inequality convexifying techniques,sufficient conditions in terms of linear matrix inequalities are given for the existence of an output-feedback controller for the discrete-time piecewiseaffine singular systems with a prescribed H∞disturbance attenuation level,and the H2norm is smaller than a given positive number. It is shown that the controller gains can be obtained by solving a family of LMIs parameterized by one or two scalar variables. The numerical examples are given to illustrate the effectiveness of the proposed design methods.展开更多
Generalized H2 (GH2) stability analysis and controller design of the uncertain discrete-time Takagi-Sugeno (T-S) fuzzy systems with state delay are studied based on a switching fuzzy model and piecewise Lyapunov f...Generalized H2 (GH2) stability analysis and controller design of the uncertain discrete-time Takagi-Sugeno (T-S) fuzzy systems with state delay are studied based on a switching fuzzy model and piecewise Lyapunov function. GH2 stability sufficient conditions are derived in terms of linear matrix inequalities (LMIs). The interactions among the fuzzy subsystems are considered. Therefore, the proposed conditions are less conservative than the previous results. Since only a set of LMIs is involved, the controller design is quite simple and numerically tractable. To illustrate the validity of the proposed method, a design example is provided.展开更多
The coupling between the Lyapunov variables and system matrices makes the problem of mixed H2/H∞ flight tracking controller design non-convex. With the aid of enhanced linear matrix inequality (LMI) approach, the n...The coupling between the Lyapunov variables and system matrices makes the problem of mixed H2/H∞ flight tracking controller design non-convex. With the aid of enhanced linear matrix inequality (LMI) approach, the non-convex optimization problem is transformed into convex LMI representations. The proposed coupling is eliminated by introducing slack variables. Moreover, a necessary and sufficient condition is derived for the mixed H2/H∞ flight tracking controller which not only stabilizes the controlled system but also satisfies the mixed H2/H∞ performance index in normal case and fault cases. The new enhanced LMI representations provide additional degrees of freedom to solve the non-convex optimization problem, and reduce the conservativeness of the controller design. Simulation results of the aero-data model in a research environment (ADMIRE) model show the advantages of the enhanced LMI approach.展开更多
This paper is concerned with the mixed H2/H∞ control with linear continuous time system and time delay. To deal with this, we presents a Stackelberg strategy by treating the control input and the disturbance as leade...This paper is concerned with the mixed H2/H∞ control with linear continuous time system and time delay. To deal with this, we presents a Stackelberg strategy by treating the control input and the disturbance as leader and follower, respectively. The leader's control strategy minimizes the cost function which is in H2 norm and the follower's control strategy maximizes the cost function which is in H∞ norm. The main technique of this paper is deal with the noncausal relationship of the variables caused by time delay in the control input by introducing two costates to capture the future information and one state to capture the past information. Through theory analyzing, the Stackelberg strategy exists uniquely. Moreover, with the assistance of the extended state space expression, the explicit expression of the strategy is obtained.展开更多
Autophagy is an evolutionarily conserved lysosome-mediated catabolic process(Klionsky,2007).Autophagy is believed to be essential for cell survival,especially when cells were exposed to stresses,such as nutrient sta...Autophagy is an evolutionarily conserved lysosome-mediated catabolic process(Klionsky,2007).Autophagy is believed to be essential for cell survival,especially when cells were exposed to stresses,such as nutrient starvation.展开更多
Four wheel steering(4 WS) technology can effectively improve the vehicle handling stability and driving safety. In order to fully consider the influence of the rear wheel steering, the vehicle dynamics model of 4 WS v...Four wheel steering(4 WS) technology can effectively improve the vehicle handling stability and driving safety. In order to fully consider the influence of the rear wheel steering, the vehicle dynamics model of 4 WS vehicle, including the rear wheel steering by wire and two degrees of freedom vehicle model of 4 WS vehicle, is established in this paper. The desired yaw rate is obtained according to the variable transmission ratio strategy. The yaw rate tracking strategy is applied to 4 WS vehicle and rear wheel steering resistance moment is taken into account. Based on the robust control theory, H_2/H_∞ mixed robust controller design is carried to research the stability control of 4 WS vehicle. Finally, the closed-loop simulation added driver model based on preview theory is carried out. The simulation results indicate that the designed H_2/H_∞ mixed robust controller can achieve the stability control.展开更多
This paper presents the notions of exact observability and exact detectability for Markov jump linear stochastic systems of Ito type with multiplieative noise (for short, MJLSS). Stochastic Popov-Belevith-Hautus (...This paper presents the notions of exact observability and exact detectability for Markov jump linear stochastic systems of Ito type with multiplieative noise (for short, MJLSS). Stochastic Popov-Belevith-Hautus (PBH) Criterions for exact observability and exact detectability are respectively obtained. As an application, stochastic H2/H∞ control for such MJLSS is discussed under exact detectability.展开更多
The finite horizon H_2/H_∞ control problem of mean-field type for discrete-time systems is considered in this paper. Firstly, the authors derive a mean-field stochastic bounded real lemma(SBRL). Secondly, a sufficien...The finite horizon H_2/H_∞ control problem of mean-field type for discrete-time systems is considered in this paper. Firstly, the authors derive a mean-field stochastic bounded real lemma(SBRL). Secondly, a sufficient condition for the solvability of discrete-time mean-field stochastic linearquadratic(LQ) optimal control is presented. Thirdly, based on SBRL and LQ results, this paper establishes a sufficient condition for the existence of discrete-time stochastic H_2/H_∞ control of meanfield type via the solvability of coupled matrix-valued equations.展开更多
Abstract This paper is concerned with the mixed H2/H∞ control for stochastic systems with random coefficients, which is actually a control combining the H2 optimization with the H∞ robust performance as the name of ...Abstract This paper is concerned with the mixed H2/H∞ control for stochastic systems with random coefficients, which is actually a control combining the H2 optimization with the H∞ robust performance as the name of H2/H∞ reveals. Based on the classical theory of linear-quadratic (LQ, for short) optimal control, the sufficient and necessary conditions for the existence and uniqueness of the solution to the indefinite backward stochastic Riccati equation (BSRE, for short) associated with H∞ robustness are derived. Then the sufficient and necessary conditions for the existence of the H2/H∞ control are given utilizing a pair of coupled stochastic Pdccati equations.展开更多
Hydrogen sul fi de(H_2S) is recognized as one of three gasotransmitters together with nitric oxide(NO) and carbon monoxide(CO). As a signaling molecule, H_2S plays an important role in physiology and shows great poten...Hydrogen sul fi de(H_2S) is recognized as one of three gasotransmitters together with nitric oxide(NO) and carbon monoxide(CO). As a signaling molecule, H_2S plays an important role in physiology and shows great potential in pharmaceutical applications. Along this line, there is a need for the development of H_2S prodrugs for various reasons. In this review, we summarize different H_2S prodrugs, their chemical properties, and some of their potential therapeutic applications.展开更多
文摘Roll motion of ships can be distinguished in two parts:an unavoidable part due to their natural movement while turning and an unwanted and avoidable part that is due to encounter with waves and rough seas in general.For the attenuation of the unwanted part of roll motion,ways have been developed such as addition of controllable fins and changes in shape.This paper investigates the effectiveness of augmenting the rudder used for rejecting part of the unwanted roll,while maintaining steering and course changing ability.For this purpose,a controller is designed,which acts through intentional superposition of fast,compared with course change,movements of rudder,in order to attenuate the high-frequency roll effects from encountering rough seas.The results obtained by simulation to exogenous disturbance support the conclusion that the roll stabilization for displacement can be effective at least when displacement hull vessels are considered.Moreover,robust stability and performance is verified for the proposed control scheme over the entire operating range of interest.
文摘The time domain guideposts requirements of a pump-motor system is transfered into a series of constraints which express the robust performance upper bound and regional poles limits of the closed loop system. Then the servo system control problem is transferred into the problem of robust performance optimizing under regional poles constrains described by linear matrix inequality (LMI). These LMIs are easy to solve through the Matlab LMI-toolbox. Simulations indicate that the controller has excellent dynamic, static and disturbance rejection performance, and the control system is robust and has perfect H2 performance to the bounded external torque disturbance.
基金Project(50775225) supported by the National Natural Science Foundation of ChinaProjects(CSTC, 2008AC6097, 2008BA6025) supported by National Natural Science Foundation of Chongqing, China
文摘A new semi-active suspension control strategy through mixed H2/H∞ robust technique was developed due to its flexibility and robustness to model uncertainties.A full car model with seven degrees of freedom was established to demonstrate the effectiveness of the new control approach.Magneto-rheological(MR) dampers were designed,manufactured and characterized as available semi-active actuators in the developed semi-active suspension system.The four independent mixed H2/H∞ controllers were devised in order to perform a distributed semi-active control system in the vehicle by which the response velocity and reliability can be improved significantly.The performance of the proposed new approach was investigated in time and frequency domains.A good balance between vehicle's comfort and road holding was achieved.An effective and practical control strategy for semi-active suspension system was thus obtained.This new approach exhibits some advantages in implementation,performance flexibility and robustness compared to existing methods.
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.
文摘This paper is concerned with the H2 estimation and control problems for uncertain discretetime systems with norm-bounded parameter uncertainty. We first present an analysis result on H2 norm bound for a stable uncertain system in terms of linear matrix inequalities (LMIs). A solution to the robust H2 estimation problem is then derived in terms of two LMIs. As compared to the existing results, our result on robust H2 estimation is more general. In addition, explicit search of appropriate scaling parameters is not needed as the optimization is convex in the scaling parameters. The LMI approach is also extended to solve the robust H2 control problem which has been difficult for the traditional Riccati equation approach since no separation principle has been known for uncertain systems. The design approach is demonstrated through a simple example.
基金This work was supported by the Science Foundation of Education Commission of Hubei Province(No.D200613002)the Doctoral Pre-ResearchFoundation of Three Gorges University.
文摘This paper presents an improved method for H-two control with regional stability constraints for the closedloop system. The controller is given by the convex combination of a set of fixed gains. Both continuous and discrete-time systems in a known polytopic domain are investigated. New LMI-based sufficient conditions for the existence of parameterdependent Lyapunov functions are proposed. Numerical examples are given to show the proposed conditions provide useful and less conservative results for the problems of H-two control with regional stability constraints.
基金supported by the Doctoral foundation of University of Jinan(XBS1213)the National Natural Science Foundation of China(11101242)
文摘A necessary maximum principle is given for nonzero-sum stochastic Oltterential games with random jumps. The result is applied to solve the H2/H∞ control problem of stochastic systems with random jumps. A necessary and sufficient condition for the existence of a unique solution to the H2/H∞ control problem is derived. The resulting solution is given by the solution of an uncontrolled forward backward stochastic differential equation with random jumps.
基金Sponsored by the Ministerial Level Advanced Research Foundation (G423BQ0110)
文摘The problem of H2 output feedback control for generalized system with structural uncertainties is studied using linear matrix inequality approach. A sufficient condition Of linear matrix inequality is presented such that the closed-loop system is stable and satisfies H2 performance for all admissible uncertainties. Furthermore, the solution of the controller is given. An H2 output feedback controller is designed in the airborne dispenser pitch channel, and the simulation results show that the controller is effective.
基金Sponsored by the National Natural Science Foundation of China (Grant No.90716028)
文摘Based upon the theory of the nonlinear quadric two-person nonzero-sum differential game,the fact that the time-limited mixed H2/H∞ control problem can be turned into the problem of solving the state feedback Nash balance point is mentioned. Upon this,a theorem about the solution of the state feedback control is given,the Lyapunov stabilization of the nonlinear system under this control is proved,too. At the same time,this solution is used to design the nonlinear H2/H∞ guidance law of the relative motion between the missile and the target in three-dimensional(3D) space. By solving two coupled Hamilton-Jacobi partial differential inequalities(HJPDI),a control with more robust stabilities and more robust performances is obtained. With different H∞ performance indexes,the correlative weighting factors of the control are analytically designed. At last,simulations under different robust performance indexes and under different initial conditions and under the cases of intercepting different maneuvering targets are carried out. All results indicate that the designed law is valid.
基金This work is supported by the National Natural Science Foundation of China (No.60374002 and No.60421002) the 973 program of China (No.2002CB312200) and the program for New Century Excellent Talents in University (No.NCET-04-0547).
文摘The general discrete-time Single-Input Single-Output (SISO) mixed H2/l1 control problem is considered in this paper. It is found that the existing results of duality theory cannot be directly applied to this infinite dimension optimisation problem. By means of two finite dimension approximate problems, to which duality theory can be applied, the dual of the mixed H2/l1 control problem is verified to be the limit of the duals of these two approximate problems.
基金Sponsored by the National Natural Science Foundation of China(Grant No.61004038)
文摘This paper is concerned with the problem of designing robust H∞and H2static output feedback controllers for a class of discrete-time piecewise-affine singular systems with norm-bounded time-varying parameters uncertainties. Based on a piecewise singular Lyapunov function combined with S-procedure,Projection lemma and some matrix inequality convexifying techniques,sufficient conditions in terms of linear matrix inequalities are given for the existence of an output-feedback controller for the discrete-time piecewiseaffine singular systems with a prescribed H∞disturbance attenuation level,and the H2norm is smaller than a given positive number. It is shown that the controller gains can be obtained by solving a family of LMIs parameterized by one or two scalar variables. The numerical examples are given to illustrate the effectiveness of the proposed design methods.
文摘Generalized H2 (GH2) stability analysis and controller design of the uncertain discrete-time Takagi-Sugeno (T-S) fuzzy systems with state delay are studied based on a switching fuzzy model and piecewise Lyapunov function. GH2 stability sufficient conditions are derived in terms of linear matrix inequalities (LMIs). The interactions among the fuzzy subsystems are considered. Therefore, the proposed conditions are less conservative than the previous results. Since only a set of LMIs is involved, the controller design is quite simple and numerically tractable. To illustrate the validity of the proposed method, a design example is provided.
文摘The coupling between the Lyapunov variables and system matrices makes the problem of mixed H2/H∞ flight tracking controller design non-convex. With the aid of enhanced linear matrix inequality (LMI) approach, the non-convex optimization problem is transformed into convex LMI representations. The proposed coupling is eliminated by introducing slack variables. Moreover, a necessary and sufficient condition is derived for the mixed H2/H∞ flight tracking controller which not only stabilizes the controlled system but also satisfies the mixed H2/H∞ performance index in normal case and fault cases. The new enhanced LMI representations provide additional degrees of freedom to solve the non-convex optimization problem, and reduce the conservativeness of the controller design. Simulation results of the aero-data model in a research environment (ADMIRE) model show the advantages of the enhanced LMI approach.
基金This work was supported by the National Natural Science Foundation of China (Nos. 61633014, 61573220, 61573221) and the Fundamental Research Funds of Shandong University (No. 201 7JC009).
文摘This paper is concerned with the mixed H2/H∞ control with linear continuous time system and time delay. To deal with this, we presents a Stackelberg strategy by treating the control input and the disturbance as leader and follower, respectively. The leader's control strategy minimizes the cost function which is in H2 norm and the follower's control strategy maximizes the cost function which is in H∞ norm. The main technique of this paper is deal with the noncausal relationship of the variables caused by time delay in the control input by introducing two costates to capture the future information and one state to capture the past information. Through theory analyzing, the Stackelberg strategy exists uniquely. Moreover, with the assistance of the extended state space expression, the explicit expression of the strategy is obtained.
基金supported by the National Basic Research Program of China (973 Program)(No.2016YFA0100400)the National Natural Science Foundation of China(No.81773009)
文摘Autophagy is an evolutionarily conserved lysosome-mediated catabolic process(Klionsky,2007).Autophagy is believed to be essential for cell survival,especially when cells were exposed to stresses,such as nutrient starvation.
基金supported by the National Natural Science Foundation of China(Grant No.51375007)the Fundamental Research Funds for the Central Universities(Grant No.NE2016002)Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(Grant No.GZKF-201605)
文摘Four wheel steering(4 WS) technology can effectively improve the vehicle handling stability and driving safety. In order to fully consider the influence of the rear wheel steering, the vehicle dynamics model of 4 WS vehicle, including the rear wheel steering by wire and two degrees of freedom vehicle model of 4 WS vehicle, is established in this paper. The desired yaw rate is obtained according to the variable transmission ratio strategy. The yaw rate tracking strategy is applied to 4 WS vehicle and rear wheel steering resistance moment is taken into account. Based on the robust control theory, H_2/H_∞ mixed robust controller design is carried to research the stability control of 4 WS vehicle. Finally, the closed-loop simulation added driver model based on preview theory is carried out. The simulation results indicate that the designed H_2/H_∞ mixed robust controller can achieve the stability control.
基金supported by National Natural Science Foundation of China under Grant Nos 60774020, 60736028,and 60821091
文摘This paper presents the notions of exact observability and exact detectability for Markov jump linear stochastic systems of Ito type with multiplieative noise (for short, MJLSS). Stochastic Popov-Belevith-Hautus (PBH) Criterions for exact observability and exact detectability are respectively obtained. As an application, stochastic H2/H∞ control for such MJLSS is discussed under exact detectability.
基金supported by the National Natural Science Foundation of China under Grant Nos.61573227,61633014the Research Fund for the Taishan Scholar Project of Shandong Province of China+1 种基金the SDUST Research Fund under Grant No.2015TDJH105the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources under Grant No.LAPS16011
文摘The finite horizon H_2/H_∞ control problem of mean-field type for discrete-time systems is considered in this paper. Firstly, the authors derive a mean-field stochastic bounded real lemma(SBRL). Secondly, a sufficient condition for the solvability of discrete-time mean-field stochastic linearquadratic(LQ) optimal control is presented. Thirdly, based on SBRL and LQ results, this paper establishes a sufficient condition for the existence of discrete-time stochastic H_2/H_∞ control of meanfield type via the solvability of coupled matrix-valued equations.
文摘Abstract This paper is concerned with the mixed H2/H∞ control for stochastic systems with random coefficients, which is actually a control combining the H2 optimization with the H∞ robust performance as the name of H2/H∞ reveals. Based on the classical theory of linear-quadratic (LQ, for short) optimal control, the sufficient and necessary conditions for the existence and uniqueness of the solution to the indefinite backward stochastic Riccati equation (BSRE, for short) associated with H∞ robustness are derived. Then the sufficient and necessary conditions for the existence of the H2/H∞ control are given utilizing a pair of coupled stochastic Pdccati equations.
文摘Hydrogen sul fi de(H_2S) is recognized as one of three gasotransmitters together with nitric oxide(NO) and carbon monoxide(CO). As a signaling molecule, H_2S plays an important role in physiology and shows great potential in pharmaceutical applications. Along this line, there is a need for the development of H_2S prodrugs for various reasons. In this review, we summarize different H_2S prodrugs, their chemical properties, and some of their potential therapeutic applications.