A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magne...A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magnetic field to control the plasma＇s displacement. With the development of EAST, new demands on the new fast control power supply have led to an enhanced ability of fast response and output current, as well as a new control mode. The structure of cascaded and paralleled H-bridges can meet the demand of extended capacity, and digital control can reMize current and voltage mixed control mode. The validity of the proposed scheme is confirmed by experiments.展开更多
EVs （electric vehicles） have been widely accepted as a promising solution for reducing oil consumption, air pollution and greenhouse gas emission. The number of EVs is growing very fast over the years. However, the ...EVs （electric vehicles） have been widely accepted as a promising solution for reducing oil consumption, air pollution and greenhouse gas emission. The number of EVs is growing very fast over the years. However, the high adoption of EVs will impose a burden on the power system, especially for neighborhood level network. In this paper, we propose a mixed control framework for EV charging scheduling to mitigate its impact on the power network. A metric for modeling customer＇s satisfaction is also proposed to compare the user satisfaction for different algorithms. The impacts of the proposed algorithms on EV charging cost, EV penetration and peak power reduction are evaluated with real data for a neighborhood level network. The simulation results demonstrate the effectiveness of the proposed algorithms.展开更多
The author investigates the nonlinear parabolic variational inequality derived from the mixed stochastic control problem on finite horizon.Supposing that some suffi-ciently smooth conditions hold,by the dynamic progra...The author investigates the nonlinear parabolic variational inequality derived from the mixed stochastic control problem on finite horizon.Supposing that some suffi-ciently smooth conditions hold,by the dynamic programming principle,the author builds the Hamilton-Jacobi-Bellman(HJB for short)variational inequality for the value function.The author also proves that the value function is the unique viscosity solution of the HJB variational inequality and gives an application to the quasi-variational inequality.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 non-conv...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 control synthesis problem via dynamic output feedback for linear continuous-time systems with mixed frequency small gain specifications.A new method for designing dynamic output feedba...This paper is concerned with the control synthesis problem via dynamic output feedback for linear continuous-time systems with mixed frequency small gain specifications.A new method for designing dynamic output feedback controllers is presented such that the resulting closed-loop systems are asymptotically stable and meet the requirements of small gain specifications in both finite frequency ranges and the entire frequency range.The design conditions are given in terms of solutions to a set of linear matrix inequalities(LMIs).Finally,a numerical example is given to illustrate the design procedure and the advantage of the proposed method in comparison with the existing one.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
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
Highly efficient and stable hybrid white organic light-emitting diodes （HWOLEDs） with a mixed bipolar interlayer between fluorescent blue and phosphorescent yellow emitting layers are demonstrated. The bipolar inter...Highly efficient and stable hybrid white organic light-emitting diodes （HWOLEDs） with a mixed bipolar interlayer between fluorescent blue and phosphorescent yellow emitting layers are demonstrated. The bipolar interlayer is a mixture of p-type diphenyl （l0-phenyl-lOH-spiro [acridine-9,9＇-fluoren]-3Lyl） phosphine oxide and n-type 2＇,2- （1,3,5-benzinetriyl）-tris（1-phenyl-l-H-benzimidazole）. The electroluminance and Commission Internationale de l＇Eclairage （CIE1931） coordinates＇ characteristics can be modulated easily by adjusting the ratio of the hole- predominated material to the electron-predominated material in the interlayer. The hybrid WOLED with a p-type：n-type ratio of 1：3 shows a maximum current efficiency and power efficiency of 61.1 ed/A and 55.8 lm/W, respectively, with warm white CIE coordinates of （0.34, 0.43）. The excellent efficiency and adaptive CIE coordi- nates are attributed to the mixed interlayer with improved charge carrier balance, optimized exciton distribution, and enhanced harvesting of singlet and triplet excitons.展开更多
In this paper, the state-feedback Nash game based mixed H2/H∞ design^（[1, 2]）has been extended for output feedback case. The algorithm is applied to control bioreactor system with a Laguerre-Wavelet Network（LWN）^...In this paper, the state-feedback Nash game based mixed H2/H∞ design^（[1, 2]）has been extended for output feedback case. The algorithm is applied to control bioreactor system with a Laguerre-Wavelet Network（LWN）^（[3, 4]）model of the bioreactor.This is achieved by using the LWN model as a deviation model and by successively linearising the deviation model along the state trajectory. For reducing the approximation error and to improve the controller performance, symbolic derivation algorithm, viz.,automatic differentiation is employed. A cautionary note is also given on the fragility of the output feedback mixed H2/H∞ model predictive controller^（[4, 5]）due to its sensitivity to its own parametric changes.展开更多
The control problems associated with vehicle height adjustment of electronically controlled air suspension （ECAS） still pose theoretical challenges for researchers, which manifest themselves in the publications on t...The control problems associated with vehicle height adjustment of electronically controlled air suspension （ECAS） still pose theoretical challenges for researchers, which manifest themselves in the publications on this subject over the last years. This paper deals with modeling and control of a vehicle height adjustment system for ECAS, which is an example of a hybrid dynamical system due to the coexistence and coupling of continuous variables and discrete events. A mixed logical dynamical （MLD） modeling approach is chosen for capturing enough details of the vehicle height adjustment process. The hybrid dynamic model is constructed on the basis of some assumptions and piecewise linear approximation for components nonlinearities. Then, the on-off statuses of solenoid valves and the piecewise approximation process are described by propositional logic, and the hybrid system is transformed into the set of linear mixed-integer equalities and inequalities, denoted as MLD model, automatically by HYSDEL. Using this model, a hybrid model predictive controller （HMPC） is tuned based on online mixed-integer quadratic optimization （MIQP）. Two different scenarios are considered in the simulation, whose results verify the height adjustment effectiveness of the proposed approach. Explicit solutions of the controller are computed to control the vehicle height adjustment system in realtime using an offline multi-parametric programming technology （MPT）, thus convert the controller into an equivalent explicit piecewise affine form. Finally, bench experiments for vehicle height lifting, holding and lowering procedures are conducted, which demonstrate that the HMPC can adjust the vehicle height by controlling the on-off statuses of solenoid valves directly. This research proposes a new modeling and control method for vehicle height adjustment of ECAS, which leads to a closed-loop system with favorable dynamical properties.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
A neural network control scheme with mixed H2/H∞performance was proposed for robot force/position control under parameter uncertainties and external disturbances. The mixed H2/H∞tracking performance ensures both rob...A neural network control scheme with mixed H2/H∞performance was proposed for robot force/position control under parameter uncertainties and external disturbances. The mixed H2/H∞tracking performance ensures both robust stability under a prescribed attenuation level for external disturbance and H2optimal tracking. The neural network was introduced to adaptively estimate nonlinear uncertainties, improving the system’s performance under parameter uncertainties as well as obtaining the H2/H∞tracking performance. The simulation shows that the control method performs better even when the system is under large modeling uncertainties and external disturbances.展开更多
This paper presents a closed-loop numerical algorithm for the quadratic optimal control problem of a linear mixed system that combines both deterministic and stochastic controls.The core idea is to numerically solve t...This paper presents a closed-loop numerical algorithm for the quadratic optimal control problem of a linear mixed system that combines both deterministic and stochastic controls.The core idea is to numerically solve two Riccati equations by using linear quadratic theory.Based on these numerical solutions,a feedback-type discretization method for the original problem is developed,along with an analysis of its convergence rate.A significant advantage of the proposed method is that it avoids the computation of backward stochastic differential equations associated with Pontryagin’s maximum principle,leading to notable improvements in computational efficiency.This work builds upon the theoretical framework established by Hu and Tang(Probab.Uncertain.Quant.Risk,4(2019),Paper No.1)and focuses on its numerical implementation.展开更多
This paper presents a substructure online hybrid test system that is extensible for geographically distributed tests. This system consists of a set of devices conventionally used for cyclic tests to load the tested su...This paper presents a substructure online hybrid test system that is extensible for geographically distributed tests. This system consists of a set of devices conventionally used for cyclic tests to load the tested substructures onto the target displacement or the target force. Due to their robustness and portability, individual sets of conventional loading devices can be transported and reconfigured to realize physical loading in geographically remote laboratories. Another appealing feature is the flexible displacement-force mixed control that is particularly suitable for specimens having large disparities in stiffness during various performance stages. To conduct a substructure online hybrid test, an extensible framework is developed, which is equipped with a generalized interface to encapsulate each substructure. Multiple tested substructures and analyzed substructures using various structural program codes can be accommodated within the single framework, simply interfaced with the boundary displacements and forces. A coordinator program is developed to keep the boundaries among all substructures compatible and equilibrated. An Interuet-based data exchange scheme is also devised to transfer data among computers equipped with different software environments. A series of online hybrid tests are introduced, and the portability, flexibility, and extensibility of the online hybrid test system are demonstrated.展开更多
The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring spee...The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It is observed that the dissolution rate increases with decreasing particle size and solid-to-liquid ratio, and increases with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is of mixed control via hydrogen ion [H＋] action, with reaction order of 0.813 and the reaction kinetics can be expressed as gmt=[1-（1-x）l/3＋y/6[（l-x）l/3＋ 1-2（1-x）2/3]. The activation energy of the process is determined to be 21.6 k J/mol. The level of the product quality is also evaluated.展开更多
In this paper,we consider the mixed optimal control of a linear stochastic system with a quadratic cost functional,with two controllers—one can choose only deterministic time functions,called the deterministic contro...In this paper,we consider the mixed optimal control of a linear stochastic system with a quadratic cost functional,with two controllers—one can choose only deterministic time functions,called the deterministic controller,while the other can choose adapted random processes,called the random controller.The optimal control is shown to exist under suitable assumptions.The optimal control is characterized via a system of fully coupled forward-backward stochastic differential equations(FBSDEs)of mean-field type.We solve the FBSDEs via solutions of two(but decoupled)Riccati equations,and give the respective optimal feedback law for both deterministic and random controllers,using solutions of both Riccati equations.The optimal state satisfies a linear stochastic differential equation(SDE)of mean-field type.Both the singular and infinite time-horizonal cases are also addressed.展开更多
Vehicle height and leveling control of electronically controlled air suspension(ECAS) still poses theoretical challenges for researchers that have not been adequately addressed in prior research. This paper investigat...Vehicle height and leveling control of electronically controlled air suspension(ECAS) still poses theoretical challenges for researchers that have not been adequately addressed in prior research. This paper investigates the design and verification of a new controller to adjust the vehicle height and to regulate the roll and pitch angles of the vehicle body(leveling control) during the height adjustment procedures. A nonlinear mechanism model of the vehicle height adjustment system is formulated to describe the dynamic behaviors of the system. By using mixed logical dynamical(MLD) approach, a novel control strategy is proposed to adjust the vehicle height by controlling the on-off statuses of the solenoid valves directly. On this basis, a correction algorithm is also designed to regulate the durations of the on-off statuses of the solenoid valves based on pulse width modulated(PWM) technology, thus the effective leveling control of the vehicle body can be guaranteed. Finally, simulations and vehicle tests results are presented to demonstrate the effectiveness and applicability of the proposed control methodology.展开更多
The return capsule needs to be launched to the moon and return back to earth in the third stage of the Chinese lunar exploration project.Therefore,it is necessary to perform simulations on the ground.This paper presen...The return capsule needs to be launched to the moon and return back to earth in the third stage of the Chinese lunar exploration project.Therefore,it is necessary to perform simulations on the ground.This paper presents an 8-cable-driven parallel manipulator to achieve end-force output in a low-gravity environment.End-force output refers to the vector sum of the external force on the end-effector.A model of end-force output is established based on a kinematics model,a dynamic model,and a force analysis of an 8-cable driven parallel manipulator.To obtain end-force output in a low-gravity environment,the cable force has to be controlled to counteract gravity.In addition,a force-position mix control strategy is proposed to proactively control the cable force according to the force optimal distribution given by the closed-form force distribution method.Furthermore,a suitable choice for an end-force output is obtained by modeling the effect of cable force on end-force output.Experimental results show that the actual cable force agrees well with the calculated force distribution,indicating that it is feasible to realize end-force output in a low gravity environment.展开更多
Reinforcement learning-based traffic signal control systems (RLTSC) can enhance dynamic adaptability, save vehicle travelling timeand promote intersection capacity. However, the existing RLTSC methods do not consider ...Reinforcement learning-based traffic signal control systems (RLTSC) can enhance dynamic adaptability, save vehicle travelling timeand promote intersection capacity. However, the existing RLTSC methods do not consider the driver’s response time requirement, sothe systems often face efficiency limitations and implementation difficulties.We propose the advance decision-making reinforcementlearning traffic signal control (AD-RLTSC) algorithm to improve traffic efficiency while ensuring safety in mixed traffic environment.First, the relationship between the intersection perception range and the signal control period is established and the trust region state(TRS) is proposed. Then, the scalable state matrix is dynamically adjusted to decide the future signal light status. The decision will bedisplayed to the human-driven vehicles (HDVs) through the bi-countdown timer mechanism and sent to the nearby connected automatedvehicles (CAVs) using the wireless network rather than be executed immediately. HDVs and CAVs optimize the driving speedbased on the remaining green (or red) time. Besides, the Double Dueling Deep Q-learning Network algorithm is used for reinforcementlearning training;a standardized reward is proposed to enhance the performance of intersection control and prioritized experiencereplay is adopted to improve sample utilization. The experimental results on vehicle micro-behaviour and traffic macro-efficiencyshowed that the proposed AD-RLTSC algorithm can simultaneously improve both traffic efficiency and traffic flow stability.展开更多
基金supported by ITER Program of China(973 Program)(No.2011GB109002)National Natural Science Foundation of China(No.11275056)Hefei University of Technology Doctor Research Foundation of China(No.2011HGBZ1292)
文摘A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magnetic field to control the plasma＇s displacement. With the development of EAST, new demands on the new fast control power supply have led to an enhanced ability of fast response and output current, as well as a new control mode. The structure of cascaded and paralleled H-bridges can meet the demand of extended capacity, and digital control can reMize current and voltage mixed control mode. The validity of the proposed scheme is confirmed by experiments.
文摘EVs （electric vehicles） have been widely accepted as a promising solution for reducing oil consumption, air pollution and greenhouse gas emission. The number of EVs is growing very fast over the years. However, the high adoption of EVs will impose a burden on the power system, especially for neighborhood level network. In this paper, we propose a mixed control framework for EV charging scheduling to mitigate its impact on the power network. A metric for modeling customer＇s satisfaction is also proposed to compare the user satisfaction for different algorithms. The impacts of the proposed algorithms on EV charging cost, EV penetration and peak power reduction are evaluated with real data for a neighborhood level network. The simulation results demonstrate the effectiveness of the proposed algorithms.
文摘The author investigates the nonlinear parabolic variational inequality derived from the mixed stochastic control problem on finite horizon.Supposing that some suffi-ciently smooth conditions hold,by the dynamic programming principle,the author builds the Hamilton-Jacobi-Bellman(HJB for short)variational inequality for the value function.The author also proves that the value function is the unique viscosity solution of the HJB variational inequality and gives an application to the quasi-variational inequality.
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Supported by Program for New Century Excellent Talents in University(NCET-04-0283)the Funds for Creative Research Groups of China(60521003)+4 种基金Program for Changjiang Scholars and Innovative Research Team in University(IRT0421)the State Key Program of National Natural Science Foundation of China(60534010)and National Natural Science Foundation of China(60674021)the Funds of Ph.D.Program of Ministry of Education,China(20060145019)the 111 Project(B08015)
文摘This paper is concerned with the control synthesis problem via dynamic output feedback for linear continuous-time systems with mixed frequency small gain specifications.A new method for designing dynamic output feedback controllers is presented such that the resulting closed-loop systems are asymptotically stable and meet the requirements of small gain specifications in both finite frequency ranges and the entire frequency range.The design conditions are given in terms of solutions to a set of linear matrix inequalities(LMIs).Finally,a numerical example is given to illustrate the design procedure and the advantage of the proposed method in comparison with the existing one.
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 the National Natural Science Foundation of China under Grant No 91441201
文摘Highly efficient and stable hybrid white organic light-emitting diodes （HWOLEDs） with a mixed bipolar interlayer between fluorescent blue and phosphorescent yellow emitting layers are demonstrated. The bipolar interlayer is a mixture of p-type diphenyl （l0-phenyl-lOH-spiro [acridine-9,9＇-fluoren]-3Lyl） phosphine oxide and n-type 2＇,2- （1,3,5-benzinetriyl）-tris（1-phenyl-l-H-benzimidazole）. The electroluminance and Commission Internationale de l＇Eclairage （CIE1931） coordinates＇ characteristics can be modulated easily by adjusting the ratio of the hole- predominated material to the electron-predominated material in the interlayer. The hybrid WOLED with a p-type：n-type ratio of 1：3 shows a maximum current efficiency and power efficiency of 61.1 ed/A and 55.8 lm/W, respectively, with warm white CIE coordinates of （0.34, 0.43）. The excellent efficiency and adaptive CIE coordi- nates are attributed to the mixed interlayer with improved charge carrier balance, optimized exciton distribution, and enhanced harvesting of singlet and triplet excitons.
文摘In this paper, the state-feedback Nash game based mixed H2/H∞ design^（[1, 2]）has been extended for output feedback case. The algorithm is applied to control bioreactor system with a Laguerre-Wavelet Network（LWN）^（[3, 4]）model of the bioreactor.This is achieved by using the LWN model as a deviation model and by successively linearising the deviation model along the state trajectory. For reducing the approximation error and to improve the controller performance, symbolic derivation algorithm, viz.,automatic differentiation is employed. A cautionary note is also given on the fragility of the output feedback mixed H2/H∞ model predictive controller^（[4, 5]）due to its sensitivity to its own parametric changes.
基金Supported by National Natural Science Foundation of China(Grant No.51375212)Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions of China+1 种基金Research Fund for the Doctoral Program of Higher Education of China(Grant No.20133227130001)China Postdoctoral Science Foundation(Grant No.2014M551518)
文摘The control problems associated with vehicle height adjustment of electronically controlled air suspension （ECAS） still pose theoretical challenges for researchers, which manifest themselves in the publications on this subject over the last years. This paper deals with modeling and control of a vehicle height adjustment system for ECAS, which is an example of a hybrid dynamical system due to the coexistence and coupling of continuous variables and discrete events. A mixed logical dynamical （MLD） modeling approach is chosen for capturing enough details of the vehicle height adjustment process. The hybrid dynamic model is constructed on the basis of some assumptions and piecewise linear approximation for components nonlinearities. Then, the on-off statuses of solenoid valves and the piecewise approximation process are described by propositional logic, and the hybrid system is transformed into the set of linear mixed-integer equalities and inequalities, denoted as MLD model, automatically by HYSDEL. Using this model, a hybrid model predictive controller （HMPC） is tuned based on online mixed-integer quadratic optimization （MIQP）. Two different scenarios are considered in the simulation, whose results verify the height adjustment effectiveness of the proposed approach. Explicit solutions of the controller are computed to control the vehicle height adjustment system in realtime using an offline multi-parametric programming technology （MPT）, thus convert the controller into an equivalent explicit piecewise affine form. Finally, bench experiments for vehicle height lifting, holding and lowering procedures are conducted, which demonstrate that the HMPC can adjust the vehicle height by controlling the on-off statuses of solenoid valves directly. This research proposes a new modeling and control method for vehicle height adjustment of ECAS, which leads to a closed-loop system with favorable dynamical properties.
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.
文摘A neural network control scheme with mixed H2/H∞performance was proposed for robot force/position control under parameter uncertainties and external disturbances. The mixed H2/H∞tracking performance ensures both robust stability under a prescribed attenuation level for external disturbance and H2optimal tracking. The neural network was introduced to adaptively estimate nonlinear uncertainties, improving the system’s performance under parameter uncertainties as well as obtaining the H2/H∞tracking performance. The simulation shows that the control method performs better even when the system is under large modeling uncertainties and external disturbances.
基金supported by the Graduate Research Innovation Project of Southwest University(Grant No.SWUS24080)。
文摘This paper presents a closed-loop numerical algorithm for the quadratic optimal control problem of a linear mixed system that combines both deterministic and stochastic controls.The core idea is to numerically solve two Riccati equations by using linear quadratic theory.Based on these numerical solutions,a feedback-type discretization method for the original problem is developed,along with an analysis of its convergence rate.A significant advantage of the proposed method is that it avoids the computation of backward stochastic differential equations associated with Pontryagin’s maximum principle,leading to notable improvements in computational efficiency.This work builds upon the theoretical framework established by Hu and Tang(Probab.Uncertain.Quant.Risk,4(2019),Paper No.1)and focuses on its numerical implementation.
基金Public Benefit Research Foundation under Grant No.201108006Natural Science Foundation under Grant No.51161120360+2 种基金Heilongjiang Overseas Funding under Grant No.LC201002 of ChinaGrant-in-Aid for Scientific Research(Basic Research Category A,19206060)Japan Society for the Promotion of Science
文摘This paper presents a substructure online hybrid test system that is extensible for geographically distributed tests. This system consists of a set of devices conventionally used for cyclic tests to load the tested substructures onto the target displacement or the target force. Due to their robustness and portability, individual sets of conventional loading devices can be transported and reconfigured to realize physical loading in geographically remote laboratories. Another appealing feature is the flexible displacement-force mixed control that is particularly suitable for specimens having large disparities in stiffness during various performance stages. To conduct a substructure online hybrid test, an extensible framework is developed, which is equipped with a generalized interface to encapsulate each substructure. Multiple tested substructures and analyzed substructures using various structural program codes can be accommodated within the single framework, simply interfaced with the boundary displacements and forces. A coordinator program is developed to keep the boundaries among all substructures compatible and equilibrated. An Interuet-based data exchange scheme is also devised to transfer data among computers equipped with different software environments. A series of online hybrid tests are introduced, and the portability, flexibility, and extensibility of the online hybrid test system are demonstrated.
文摘The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It is observed that the dissolution rate increases with decreasing particle size and solid-to-liquid ratio, and increases with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is of mixed control via hydrogen ion [H＋] action, with reaction order of 0.813 and the reaction kinetics can be expressed as gmt=[1-（1-x）l/3＋y/6[（l-x）l/3＋ 1-2（1-x）2/3]. The activation energy of the process is determined to be 21.6 k J/mol. The level of the product quality is also evaluated.
基金Lebesgue center of mathematics“Investissements d’avenir”program-ANR-11-LABX-0020-01,by CAESARS-ANR-15-CE05-0024MFG-ANR-16-CE40-0015-01.Tang acknowledges research supported by National Science Foundation of China(Grant No.11631004)Science and Technology Commission of Shanghai Municipality(Grant No.14XD1400400).
文摘In this paper,we consider the mixed optimal control of a linear stochastic system with a quadratic cost functional,with two controllers—one can choose only deterministic time functions,called the deterministic controller,while the other can choose adapted random processes,called the random controller.The optimal control is shown to exist under suitable assumptions.The optimal control is characterized via a system of fully coupled forward-backward stochastic differential equations(FBSDEs)of mean-field type.We solve the FBSDEs via solutions of two(but decoupled)Riccati equations,and give the respective optimal feedback law for both deterministic and random controllers,using solutions of both Riccati equations.The optimal state satisfies a linear stochastic differential equation(SDE)of mean-field type.Both the singular and infinite time-horizonal cases are also addressed.
基金supported by the National Natural Science Foundation of China(Grant Nos.51375212,61403172&51305167)Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Key Research and Development Program of Jiangsu Province(Grant No.BE2016149)
文摘Vehicle height and leveling control of electronically controlled air suspension(ECAS) still poses theoretical challenges for researchers that have not been adequately addressed in prior research. This paper investigates the design and verification of a new controller to adjust the vehicle height and to regulate the roll and pitch angles of the vehicle body(leveling control) during the height adjustment procedures. A nonlinear mechanism model of the vehicle height adjustment system is formulated to describe the dynamic behaviors of the system. By using mixed logical dynamical(MLD) approach, a novel control strategy is proposed to adjust the vehicle height by controlling the on-off statuses of the solenoid valves directly. On this basis, a correction algorithm is also designed to regulate the durations of the on-off statuses of the solenoid valves based on pulse width modulated(PWM) technology, thus the effective leveling control of the vehicle body can be guaranteed. Finally, simulations and vehicle tests results are presented to demonstrate the effectiveness and applicability of the proposed control methodology.
基金This research was supported by National Natural Science Foundation of China(No.91648107)Beijing Natural Science Foundation(No.L182041).
文摘The return capsule needs to be launched to the moon and return back to earth in the third stage of the Chinese lunar exploration project.Therefore,it is necessary to perform simulations on the ground.This paper presents an 8-cable-driven parallel manipulator to achieve end-force output in a low-gravity environment.End-force output refers to the vector sum of the external force on the end-effector.A model of end-force output is established based on a kinematics model,a dynamic model,and a force analysis of an 8-cable driven parallel manipulator.To obtain end-force output in a low-gravity environment,the cable force has to be controlled to counteract gravity.In addition,a force-position mix control strategy is proposed to proactively control the cable force according to the force optimal distribution given by the closed-form force distribution method.Furthermore,a suitable choice for an end-force output is obtained by modeling the effect of cable force on end-force output.Experimental results show that the actual cable force agrees well with the calculated force distribution,indicating that it is feasible to realize end-force output in a low gravity environment.
基金Science&Technology Research and Development Program of China Railway(Grant No.N2021G045)the Beijing Municipal Natural Science Foundation(Grant No.L191013)the Joint Funds of the Natural Science Foundation of China(Grant No.U1934222).
文摘Reinforcement learning-based traffic signal control systems (RLTSC) can enhance dynamic adaptability, save vehicle travelling timeand promote intersection capacity. However, the existing RLTSC methods do not consider the driver’s response time requirement, sothe systems often face efficiency limitations and implementation difficulties.We propose the advance decision-making reinforcementlearning traffic signal control (AD-RLTSC) algorithm to improve traffic efficiency while ensuring safety in mixed traffic environment.First, the relationship between the intersection perception range and the signal control period is established and the trust region state(TRS) is proposed. Then, the scalable state matrix is dynamically adjusted to decide the future signal light status. The decision will bedisplayed to the human-driven vehicles (HDVs) through the bi-countdown timer mechanism and sent to the nearby connected automatedvehicles (CAVs) using the wireless network rather than be executed immediately. HDVs and CAVs optimize the driving speedbased on the remaining green (or red) time. Besides, the Double Dueling Deep Q-learning Network algorithm is used for reinforcementlearning training;a standardized reward is proposed to enhance the performance of intersection control and prioritized experiencereplay is adopted to improve sample utilization. The experimental results on vehicle micro-behaviour and traffic macro-efficiencyshowed that the proposed AD-RLTSC algorithm can simultaneously improve both traffic efficiency and traffic flow stability.
