The hand-written Chinese characters reorganization input system, introduced by the Shenbi Electronics, Science and Technology Corporation Ltd. in Guangzhou, is made of advancedoverseas computer identification technolo...The hand-written Chinese characters reorganization input system, introduced by the Shenbi Electronics, Science and Technology Corporation Ltd. in Guangzhou, is made of advancedoverseas computer identification technology. It consists of an input board and identification software.展开更多
The paper proposed a terminal sliding mode control method for the delayed input system with uncertainties. Firstly, through the state transformation, the original system was transformed into the non-delayed controllab...The paper proposed a terminal sliding mode control method for the delayed input system with uncertainties. Firstly, through the state transformation, the original system was transformed into the non-delayed controllabte canonical form system. Then the paper designed a terminal sliding mode and terminal sliding control law with Lyapunov method for the transformed system. Through the method, the reaching time of the any initial state and the convergencing time to the equilibrium points are constrained in finite time. The simulation results show the validation of the method.展开更多
Dear Editor,It is well known that event-triggered control(ETC)is an effective approach in addressing networked control problems for Industry 5.0.Its feasibility,however,is still restricted to canonical nonlinear syste...Dear Editor,It is well known that event-triggered control(ETC)is an effective approach in addressing networked control problems for Industry 5.0.Its feasibility,however,is still restricted to canonical nonlinear systems so far.Considering this,a gradient-based adaptive ETC scheme for noncanonical nonlinear systems is newly developed in this letter,where the hysteresis input constraints are considered also.By proper decomposition,the technical issue of handling ETC-induced measurement errors and hysteresis inputs can be transformed into the robustness problem to bounded disturbance-like terms,which is then addressed by integrating a switching modification strategy in adaptive design and developing a novel augmented error-based analysis framework.Experimental results based on a practical piezoactuator confirm the effectiveness of the proposed scheme.展开更多
Single-phase,non-isolated microinverters used in photovoltaic(PV)systems commonly encounter two persistent challenges:High-frequency leakage current and fluctuating power delivery.This paper presents a novel single-ph...Single-phase,non-isolated microinverters used in photovoltaic(PV)systems commonly encounter two persistent challenges:High-frequency leakage current and fluctuating power delivery.This paper presents a novel single-phase,non-isolated,multi-input microinverter topology with a common-ground structure that effectively eliminates ground leakage current without requiring additional active components.The proposed microinverter architecture integrates a dual-boost configuration and uses only four active switches.This is especially advantageous in terms of the component count,which is beneficial to enhance reliability,reduce cost,and simplify the overall system design.With one,two,or four PV inputs,it can operate without interruption under unbalanced voltage or partial shading and even if some inputs drop to zero.A tailored modulation scheme minimizes conduction losses while maintaining a stable direct-current(DC)-link voltage,and a decoupling capacitor efficiently absorbs the single-phase pulsating power,thus overcoming one major limitation in existing microinverter designs.By validating with a 1-kW GaN-based prototype,both the simulated and experimental results demonstrate its high efficiency,robustness,and practical suitability for cost-effective PV applications,with a peak efficiency value of 94.8%.展开更多
Enhancing the stability and performance of practical control systems in the presence of nonlinearity,time delay,and uncertainty remains a significant challenge.Particularly,a class of strict-feedback nonlinear uncerta...Enhancing the stability and performance of practical control systems in the presence of nonlinearity,time delay,and uncertainty remains a significant challenge.Particularly,a class of strict-feedback nonlinear uncertain systems characterized by unknown control directions and time-varying input delay lacks comprehensive solutions.In this paper,we propose an observerbased adaptive tracking controller to address this gap.Neural networks are utilized to handle uncertainty,and a unique coordinate transformation is employed to untangle the coupling between input delay and unknown control directions.Subsequently,a new auxiliary signal counters the impact of time-varying input delay,while a Nussbaum function is introduced to solve the problem of unknown control directions.The leverage of an advanced dynamic surface control technique avoids the“complexity explosion”and reduces boundary layer errors.Synthesizing these techniques ensures that all the closed-loop signals are semi-globally uniformly ultimately bounded(SGUUB),and the tracking error converges to a small region around the origin by selecting suitable parameters.Simulation examples are provided to demonstrate the feasibility of the proposed approach.展开更多
Unknown time-varying periodic disturbances and input delays can degrade control performance and even lead to system instability.This paper presents a novel direct adaptive output feedback controller based on the inter...Unknown time-varying periodic disturbances and input delays can degrade control performance and even lead to system instability.This paper presents a novel direct adaptive output feedback controller based on the internal model principle(IMP)to compensate for the unknown time-varying periodic disturbance in input delay systems.To reduce the design difficulty of the controller,the input delay system is equivalent to an input delay-free system by constructing stable auxiliary systems.Next,all the stabilizing controllers of the input delay system are derived by using the Youla parameterization method.Based on the IMP,an interpolation condition to completely compensate for periodic disturbances is formulated.Then,to compensate for the unknown time-varying periodic disturbance,a parameter adaptive algorithm is designed to update the Q-parameters online.The convergence of adaptive algorithms is analyzed by the Lyapunov function theory.Simulation and experimental results validated the effectiveness of the proposed method.展开更多
Dear Editor,Aiming at the consensus tracking problem of a class of unknown heterogeneous nonlinear multiagent systems(MASs)with input constraints,a novel data-driven iterative learning consensus control(ILCC)protocol ...Dear Editor,Aiming at the consensus tracking problem of a class of unknown heterogeneous nonlinear multiagent systems(MASs)with input constraints,a novel data-driven iterative learning consensus control(ILCC)protocol based on zeroing neural networks(ZNNs)is proposed.First,a dynamic linearization data model(DLDM)is acquired via dynamic linearization technology(DLT).展开更多
This study integrates explicit input enhancement into comparative continuation writing,defined as a task in which learners produce a continuation by comparing their own expression with an input text,aligning with its ...This study integrates explicit input enhancement into comparative continuation writing,defined as a task in which learners produce a continuation by comparing their own expression with an input text,aligning with its discourse structure and linguistic features,while developing their own ideas.It aims to examine whether English as a Foreign Language(EFL)learners in China exhibit differences in discourse competence and writing performance when completing comparative continuation writing combined with different input enhancement techniques,and whether the alignment effect occurs at the discourse level.Sixty first-year Chinese senior middle school students were divided into four groups:three groups engaged in comparative continuation writing with varying input enhancement,achieved by combining different techniques,while a control group performed a designated-topic writing task.The results revealed that three comparative continuation writing groups outperformed the designated-topic writing group in discourse competence,particularly in the use of temporal connectives.However,differences and some inconsistencies were observed among the comparative continuation writing groups across individual indices.The study highlights effective ways to incorporate comparative continuation writing into English instruction and demonstrates how explicit input enhancement can complement the task,simultaneously activating the alignment effect proposed by the xu-argument and enhancing discourse competence in writing.展开更多
A higher-order cumulant-based weighted least square（HOCWLS） and a higher-order cumulant-based iterative least square（HOCILS） are derived for multiple inputs single output（MISO） errors-in-variables（EIV） systems...A higher-order cumulant-based weighted least square（HOCWLS） and a higher-order cumulant-based iterative least square（HOCILS） are derived for multiple inputs single output（MISO） errors-in-variables（EIV） systems from noisy input/output data. Whether the noises of the input/output of the system are white or colored, the proposed algorithms can be insensitive to these noises and yield unbiased estimates. To realize adaptive parameter estimates, a higher-order cumulant-based recursive least square（HOCRLS） method is also studied. Convergence analysis of the HOCRLS is conducted by using the stochastic process theory and the stochastic martingale theory. It indicates that the parameter estimation error of HOCRLS consistently converges to zero under a generalized persistent excitation condition. The usefulness of the proposed algorithms is assessed through numerical simulations.展开更多
A handwriting input system was developed using three collinear ultrasonic transducers. These collinear polyvinylidene fluoride （PVDF） transducers were specially designed for the handwriting input system to give a la...A handwriting input system was developed using three collinear ultrasonic transducers. These collinear polyvinylidene fluoride （PVDF） transducers were specially designed for the handwriting input system to give a large writeable area with writing in any direction. Driver and detection circuits were developed for the handwriting system. This handwriting input system based on 2-dimensional position tracing has large writeable area （A4 paper）, low drive voltage （5 V）, and is independent of the handwriting pad or the pen.展开更多
The synchronization of Chua＇s system, whose inputs include an unknown constant parameter, is studied in this paper. A constructive method is applied to designing an adaptive controller, in which only one variable inf...The synchronization of Chua＇s system, whose inputs include an unknown constant parameter, is studied in this paper. A constructive method is applied to designing an adaptive controller, in which only one variable information of the master system is needed. With the action of control signals, the parameter of the slave system will approach the corresponding unknown parameter in the master system. At the same time, the synchronization errors will also converge to zero asymptotically. Numerical simulations show that the proposed theoretical approach is very effective.展开更多
A constrained adaptive neural network control scheme is proposed for a multi-input and multi-output（MIMO） aeroelastic system in the presence of wind gust,system uncertainties,and input nonlinearities consisting of i...A constrained adaptive neural network control scheme is proposed for a multi-input and multi-output（MIMO） aeroelastic system in the presence of wind gust,system uncertainties,and input nonlinearities consisting of input saturation and dead-zone.In regard to the input nonlinearities,the right inverse function block of the dead-zone is added before the input nonlinearities,which simplifies the input nonlinearities into an equivalent input saturation.To deal with the equivalent input saturation,an auxiliary error system is designed to compensate for the impact of the input saturation.Meanwhile,uncertainties in pitch stiffness,plunge stiffness,and pitch damping are all considered,and radial basis function neural networks（RBFNNs） are applied to approximate the system uncertainties.In combination with the designed auxiliary error system and the backstepping control technique,a constrained adaptive neural network controller is designed,and it is proven that all the signals in the closed-loop system are semi-globally uniformly bounded via the Lyapunov stability analysis method.Finally,extensive digital simulation results demonstrate the effectiveness of the proposed control scheme towards flutter suppression in spite of the integrated effects of wind gust,system uncertainties,and input nonlinearities.展开更多
In this paper,a study of control for an uncertain2-degree of freedom(DOF)helicopter system is given.The2-DOF helicopter is subject to input deadzone and output constraints.In order to cope with system uncertainties an...In this paper,a study of control for an uncertain2-degree of freedom(DOF)helicopter system is given.The2-DOF helicopter is subject to input deadzone and output constraints.In order to cope with system uncertainties and input deadzone,the neural network technique is introduced because of its capability in approximation.In order to update the weights of the neural network,an adaptive control method is utilized to improve the system adaptability.Furthermore,the integral barrier Lyapunov function(IBLF)is adopt in control design to guarantee the condition of output constraints and boundedness of the corresponding tracking errors.The Lyapunov direct method is applied in the control design to analyze system stability and convergence.Finally,numerical simulations are conducted to prove the feasibility and effectiveness of the proposed control based on the model of Quanser's 2-DOF helicopter.展开更多
This paper deals with the simultaneous estimation of states and unknown inputs for a class of Lipschitz nonlinear systems using only the measured outputs. The system is assumed to have bounded uncertainties that appea...This paper deals with the simultaneous estimation of states and unknown inputs for a class of Lipschitz nonlinear systems using only the measured outputs. The system is assumed to have bounded uncertainties that appear on both the state and output matrices. The observer design problem is formulated as a set of linear constraints which can be easily solved using linear matrix inequalities (LMI) technique. An application based on manipulator arm actuated by a direct current (DC) motor is presented to evaluate the performance of the proposed observer. The observer is applied to estimate both state and faults.展开更多
In this paper,an adaptive dynamic programming(ADP)strategy is investigated for discrete-time nonlinear systems with unknown nonlinear dynamics subject to input saturation.To save the communication resources between th...In this paper,an adaptive dynamic programming(ADP)strategy is investigated for discrete-time nonlinear systems with unknown nonlinear dynamics subject to input saturation.To save the communication resources between the controller and the actuators,stochastic communication protocols(SCPs)are adopted to schedule the control signal,and therefore the closed-loop system is essentially a protocol-induced switching system.A neural network(NN)-based identifier with a robust term is exploited for approximating the unknown nonlinear system,and a set of switch-based updating rules with an additional tunable parameter of NN weights are developed with the help of the gradient descent.By virtue of a novel Lyapunov function,a sufficient condition is proposed to achieve the stability of both system identification errors and the update dynamics of NN weights.Then,a value iterative ADP algorithm in an offline way is proposed to solve the optimal control of protocol-induced switching systems with saturation constraints,and the convergence is profoundly discussed in light of mathematical induction.Furthermore,an actor-critic NN scheme is developed to approximate the control law and the proposed performance index function in the framework of ADP,and the stability of the closed-loop system is analyzed in view of the Lyapunov theory.Finally,the numerical simulation results are presented to demonstrate the effectiveness of the proposed control scheme.展开更多
In this paper, an adaptive neural networks(NNs)tracking controller is proposed for a class of single-input/singleoutput(SISO) non-affine pure-feedback non-linear systems with input saturation. In the proposed approach...In this paper, an adaptive neural networks(NNs)tracking controller is proposed for a class of single-input/singleoutput(SISO) non-affine pure-feedback non-linear systems with input saturation. In the proposed approach, the original input saturated nonlinear system is augmented by a low pass filter.Then, new system states are introduced to implement states transformation of the augmented model. The resulting new model in affine Brunovsky form permits direct and simpler controller design by avoiding back-stepping technique and its complexity growing as done in existing methods in the literature.In controller design of the proposed approach, a state observer,based on the strictly positive real(SPR) theory, is introduced and designed to estimate the new system states, and only two neural networks are used to approximate the uncertain nonlinearities and compensate for the saturation nonlinearity of actuator. The proposed approach can not only provide a simple and effective way for construction of the controller in adaptive neural networks control of non-affine systems with input saturation, but also guarantee the tracking performance and the boundedness of all the signals in the closed-loop system. The stability of the control system is investigated by using the Lyapunov theory. Simulation examples are presented to show the effectiveness of the proposed controller.展开更多
There are few studies on the dynamic-response mechanism of near-fault and far-field ground motions for large underground structures,especially for the branch joint of a utility tunnel(UT)and its internal pipeline.Base...There are few studies on the dynamic-response mechanism of near-fault and far-field ground motions for large underground structures,especially for the branch joint of a utility tunnel(UT)and its internal pipeline.Based on the theory of a 3D viscous-spring artificial boundary,this paper deduced the equivalent nodal force when a P wave and an SV wave were vertically incident at the same time and transformed the ground motion into an equivalent nodal force using a self-developed MATLAB program,which was applied to an ABAQUS finite element model.Based on near-fault and far-field groundmotions obtained fromtheNGA-WEST2 database,the dynamic responses of a utility tunnel and its internal pipeline in different inputmechanisms of near-fault and far-field groundmotions were compared according to bidirectional input and tridirectional input,respectively.Generally,the damage to the utility tunnel caused by the near-fault ground motion was stronger than that caused by the far-field ground motion,and the vertical ground motion of near-fault ground motion aggravated the damage to the utility tunnel.In addition,the joint dislocation of the upper and lower three-way joints of the pipeline in the branch systemunder the seismic action led to local stress concentrations.In general,the branch system of the utility tunnel had good seismic performance to resist the designed earthquake action and protect the internal pipeline fromdamage during the rare earthquake.展开更多
In this paper, we study the consensus problem for a class of linear multi-agent systems(MASs) with consideration of input saturation under the self-triggered mechanism. In the context of discrete-time systems, a self-...In this paper, we study the consensus problem for a class of linear multi-agent systems(MASs) with consideration of input saturation under the self-triggered mechanism. In the context of discrete-time systems, a self-triggered strategy is developed to determine the time interval between the adjacent triggers. The triggering condition is designed by using the current sampled consensus error. Furthermore, the consensus control protocol is designed by means of a state feedback approach. It is shown that the considered multi-agent systems can reach consensus with the presented algorithm. Some sufficient conditions are proposed in the form of linear matrix inequalities(LMIs) to show the positively invariant property of the domain of attraction(DOA). Moreover, some sufficient conditions of controller synthesis are provided to enlarge the volume of the DOA and obtain the control gain matrix. A numerical example is simulated to demonstrate the effectiveness of the theoretical analysis results.展开更多
This paper considers the leader-following consensus for a class of nonlinear switched multi-agent systems(MASs)with non-strict feedback forms and input saturations under unknown switching mechanisms.First,in virtue of...This paper considers the leader-following consensus for a class of nonlinear switched multi-agent systems(MASs)with non-strict feedback forms and input saturations under unknown switching mechanisms.First,in virtue of Gaussian error functions,the saturation nonlinearities are represented by asymmetric saturation models.Second,neural networks are utilized to approximate some unknown packaged functions,and the structural property of Gaussian basis functions is introduced to handle the non-strict feedback terms.Third,by using the backstepping process,a common Lyapunov function is constructed for all the subsystems of the followers.At last,we propose an adaptive consensus protocol,under which the tracking error under arbitrary switching converges to a small neighborhood of the origin.The effectiveness of the proposed protocol is illustrated by a simulation example.展开更多
In recent years,with the continuous development of multi-agent technology represented by unmanned aerial vehicle(UAV)swarm,consensus control has become a hot spot in academic research.In this paper,we put forward a di...In recent years,with the continuous development of multi-agent technology represented by unmanned aerial vehicle(UAV)swarm,consensus control has become a hot spot in academic research.In this paper,we put forward a discrete-time consensus protocol and obtain the necessary and sufficient conditions for the second-order consensus of the second-order multi-agent system with a fixed structure under the condition of no saturation input.The theoretical derivation verifies that the two eigenvalues of the Laplacian of the communication network matrix and the sampling period have an important effect on achieving consensus.Then we construct and verify sufficient conditions to achieve consensus under the condition of input saturation constraints.The results show that consensus can be achieved if velocity,position gain,and sampling period satisfy a set of inequalities related to the eigenvalues of the Laplacian matrix.Finally,the accuracy and validity of the theoretical results are proved by numerical simulations.展开更多
文摘The hand-written Chinese characters reorganization input system, introduced by the Shenbi Electronics, Science and Technology Corporation Ltd. in Guangzhou, is made of advancedoverseas computer identification technology. It consists of an input board and identification software.
基金the National Natural Science Foundation of China (Grant No. 60474016)the Foundation of Harbin Institute of Technology(Grant No. HIT.2003.14).
文摘The paper proposed a terminal sliding mode control method for the delayed input system with uncertainties. Firstly, through the state transformation, the original system was transformed into the non-delayed controllabte canonical form system. Then the paper designed a terminal sliding mode and terminal sliding control law with Lyapunov method for the transformed system. Through the method, the reaching time of the any initial state and the convergencing time to the equilibrium points are constrained in finite time. The simulation results show the validation of the method.
文摘Dear Editor,It is well known that event-triggered control(ETC)is an effective approach in addressing networked control problems for Industry 5.0.Its feasibility,however,is still restricted to canonical nonlinear systems so far.Considering this,a gradient-based adaptive ETC scheme for noncanonical nonlinear systems is newly developed in this letter,where the hysteresis input constraints are considered also.By proper decomposition,the technical issue of handling ETC-induced measurement errors and hysteresis inputs can be transformed into the robustness problem to bounded disturbance-like terms,which is then addressed by integrating a switching modification strategy in adaptive design and developing a novel augmented error-based analysis framework.Experimental results based on a practical piezoactuator confirm the effectiveness of the proposed scheme.
基金supported by Libyan Cultural Affair/London,Libya under Grant No.13840.
文摘Single-phase,non-isolated microinverters used in photovoltaic(PV)systems commonly encounter two persistent challenges:High-frequency leakage current and fluctuating power delivery.This paper presents a novel single-phase,non-isolated,multi-input microinverter topology with a common-ground structure that effectively eliminates ground leakage current without requiring additional active components.The proposed microinverter architecture integrates a dual-boost configuration and uses only four active switches.This is especially advantageous in terms of the component count,which is beneficial to enhance reliability,reduce cost,and simplify the overall system design.With one,two,or four PV inputs,it can operate without interruption under unbalanced voltage or partial shading and even if some inputs drop to zero.A tailored modulation scheme minimizes conduction losses while maintaining a stable direct-current(DC)-link voltage,and a decoupling capacitor efficiently absorbs the single-phase pulsating power,thus overcoming one major limitation in existing microinverter designs.By validating with a 1-kW GaN-based prototype,both the simulated and experimental results demonstrate its high efficiency,robustness,and practical suitability for cost-effective PV applications,with a peak efficiency value of 94.8%.
基金National Natural Science Foundation of China(62373102)Jiangsu Natural Science Foundation(BK20221455)Anhui Provincial Key Research and Development Project(2022i01020013)。
文摘Enhancing the stability and performance of practical control systems in the presence of nonlinearity,time delay,and uncertainty remains a significant challenge.Particularly,a class of strict-feedback nonlinear uncertain systems characterized by unknown control directions and time-varying input delay lacks comprehensive solutions.In this paper,we propose an observerbased adaptive tracking controller to address this gap.Neural networks are utilized to handle uncertainty,and a unique coordinate transformation is employed to untangle the coupling between input delay and unknown control directions.Subsequently,a new auxiliary signal counters the impact of time-varying input delay,while a Nussbaum function is introduced to solve the problem of unknown control directions.The leverage of an advanced dynamic surface control technique avoids the“complexity explosion”and reduces boundary layer errors.Synthesizing these techniques ensures that all the closed-loop signals are semi-globally uniformly ultimately bounded(SGUUB),and the tracking error converges to a small region around the origin by selecting suitable parameters.Simulation examples are provided to demonstrate the feasibility of the proposed approach.
基金supported in part by the National Natural Science Foundation of China(62325302,62203076,62103065,62033001,62303079)the China Postdoctoral Science Foundation(2021M700584)+1 种基金the Natural Science Foundation of Chongqing,China(cstc2020jcyj-zdxmX0014)the Program of Shanghai Academic/Technology Research Leader(21XD1421400).
文摘Unknown time-varying periodic disturbances and input delays can degrade control performance and even lead to system instability.This paper presents a novel direct adaptive output feedback controller based on the internal model principle(IMP)to compensate for the unknown time-varying periodic disturbance in input delay systems.To reduce the design difficulty of the controller,the input delay system is equivalent to an input delay-free system by constructing stable auxiliary systems.Next,all the stabilizing controllers of the input delay system are derived by using the Youla parameterization method.Based on the IMP,an interpolation condition to completely compensate for periodic disturbances is formulated.Then,to compensate for the unknown time-varying periodic disturbance,a parameter adaptive algorithm is designed to update the Q-parameters online.The convergence of adaptive algorithms is analyzed by the Lyapunov function theory.Simulation and experimental results validated the effectiveness of the proposed method.
基金supported by the National Nature Science Foundation of China(U21A20166)the Science and Technology Development Foundation of Jilin Province(20230508095RC)+2 种基金the Major Science and Technology Projects of Jilin Province and Changchun City(20220301033GX)the Development and Reform Commission Foundation of Jilin Province(2023C034-3)the Interdisciplinary Integration and Innovation Project of JLU(JLUXKJC2020202).
文摘Dear Editor,Aiming at the consensus tracking problem of a class of unknown heterogeneous nonlinear multiagent systems(MASs)with input constraints,a novel data-driven iterative learning consensus control(ILCC)protocol based on zeroing neural networks(ZNNs)is proposed.First,a dynamic linearization data model(DLDM)is acquired via dynamic linearization technology(DLT).
文摘This study integrates explicit input enhancement into comparative continuation writing,defined as a task in which learners produce a continuation by comparing their own expression with an input text,aligning with its discourse structure and linguistic features,while developing their own ideas.It aims to examine whether English as a Foreign Language(EFL)learners in China exhibit differences in discourse competence and writing performance when completing comparative continuation writing combined with different input enhancement techniques,and whether the alignment effect occurs at the discourse level.Sixty first-year Chinese senior middle school students were divided into four groups:three groups engaged in comparative continuation writing with varying input enhancement,achieved by combining different techniques,while a control group performed a designated-topic writing task.The results revealed that three comparative continuation writing groups outperformed the designated-topic writing group in discourse competence,particularly in the use of temporal connectives.However,differences and some inconsistencies were observed among the comparative continuation writing groups across individual indices.The study highlights effective ways to incorporate comparative continuation writing into English instruction and demonstrates how explicit input enhancement can complement the task,simultaneously activating the alignment effect proposed by the xu-argument and enhancing discourse competence in writing.
基金supported by the National High Technology Researchand Development Program of China(863 Program)(2012AA121602)the Preliminary Research Program of the General Armament Department of China(51322050202)
文摘A higher-order cumulant-based weighted least square（HOCWLS） and a higher-order cumulant-based iterative least square（HOCILS） are derived for multiple inputs single output（MISO） errors-in-variables（EIV） systems from noisy input/output data. Whether the noises of the input/output of the system are white or colored, the proposed algorithms can be insensitive to these noises and yield unbiased estimates. To realize adaptive parameter estimates, a higher-order cumulant-based recursive least square（HOCRLS） method is also studied. Convergence analysis of the HOCRLS is conducted by using the stochastic process theory and the stochastic martingale theory. It indicates that the parameter estimation error of HOCRLS consistently converges to zero under a generalized persistent excitation condition. The usefulness of the proposed algorithms is assessed through numerical simulations.
基金Supported by the National Natural Science Foundation of China(Nos. 61025021,60936002, 60729308,and 61020106006)the National High-Tech Research and Development (863) Program of China (No.2006AA04Z372)the National Key Projects of Science and Technology of China (No.2009ZX02023-1-3)
文摘A handwriting input system was developed using three collinear ultrasonic transducers. These collinear polyvinylidene fluoride （PVDF） transducers were specially designed for the handwriting input system to give a large writeable area with writing in any direction. Driver and detection circuits were developed for the handwriting system. This handwriting input system based on 2-dimensional position tracing has large writeable area （A4 paper）, low drive voltage （5 V）, and is independent of the handwriting pad or the pen.
基金Project supported by the National Natural Science Foundation of China （Grant No 60502009）.
文摘The synchronization of Chua＇s system, whose inputs include an unknown constant parameter, is studied in this paper. A constructive method is applied to designing an adaptive controller, in which only one variable information of the master system is needed. With the action of control signals, the parameter of the slave system will approach the corresponding unknown parameter in the master system. At the same time, the synchronization errors will also converge to zero asymptotically. Numerical simulations show that the proposed theoretical approach is very effective.
基金supported by the National Natural Science Foundation of China(Nos.61473307 and 61304120)the Aeronautical Science Foundation of China(No. 20155896026)
文摘A constrained adaptive neural network control scheme is proposed for a multi-input and multi-output（MIMO） aeroelastic system in the presence of wind gust,system uncertainties,and input nonlinearities consisting of input saturation and dead-zone.In regard to the input nonlinearities,the right inverse function block of the dead-zone is added before the input nonlinearities,which simplifies the input nonlinearities into an equivalent input saturation.To deal with the equivalent input saturation,an auxiliary error system is designed to compensate for the impact of the input saturation.Meanwhile,uncertainties in pitch stiffness,plunge stiffness,and pitch damping are all considered,and radial basis function neural networks（RBFNNs） are applied to approximate the system uncertainties.In combination with the designed auxiliary error system and the backstepping control technique,a constrained adaptive neural network controller is designed,and it is proven that all the signals in the closed-loop system are semi-globally uniformly bounded via the Lyapunov stability analysis method.Finally,extensive digital simulation results demonstrate the effectiveness of the proposed control scheme towards flutter suppression in spite of the integrated effects of wind gust,system uncertainties,and input nonlinearities.
基金supported by the National Natural Science Foundation of China(61803085,61806052,U1713209)the Natural Science Foundation of Jiangsu Province of China(BK20180361)
文摘In this paper,a study of control for an uncertain2-degree of freedom(DOF)helicopter system is given.The2-DOF helicopter is subject to input deadzone and output constraints.In order to cope with system uncertainties and input deadzone,the neural network technique is introduced because of its capability in approximation.In order to update the weights of the neural network,an adaptive control method is utilized to improve the system adaptability.Furthermore,the integral barrier Lyapunov function(IBLF)is adopt in control design to guarantee the condition of output constraints and boundedness of the corresponding tracking errors.The Lyapunov direct method is applied in the control design to analyze system stability and convergence.Finally,numerical simulations are conducted to prove the feasibility and effectiveness of the proposed control based on the model of Quanser's 2-DOF helicopter.
文摘This paper deals with the simultaneous estimation of states and unknown inputs for a class of Lipschitz nonlinear systems using only the measured outputs. The system is assumed to have bounded uncertainties that appear on both the state and output matrices. The observer design problem is formulated as a set of linear constraints which can be easily solved using linear matrix inequalities (LMI) technique. An application based on manipulator arm actuated by a direct current (DC) motor is presented to evaluate the performance of the proposed observer. The observer is applied to estimate both state and faults.
基金supported in part by the Australian Research Council Discovery Early Career Researcher Award(DE200101128)Australian Research Council(DP190101557)。
文摘In this paper,an adaptive dynamic programming(ADP)strategy is investigated for discrete-time nonlinear systems with unknown nonlinear dynamics subject to input saturation.To save the communication resources between the controller and the actuators,stochastic communication protocols(SCPs)are adopted to schedule the control signal,and therefore the closed-loop system is essentially a protocol-induced switching system.A neural network(NN)-based identifier with a robust term is exploited for approximating the unknown nonlinear system,and a set of switch-based updating rules with an additional tunable parameter of NN weights are developed with the help of the gradient descent.By virtue of a novel Lyapunov function,a sufficient condition is proposed to achieve the stability of both system identification errors and the update dynamics of NN weights.Then,a value iterative ADP algorithm in an offline way is proposed to solve the optimal control of protocol-induced switching systems with saturation constraints,and the convergence is profoundly discussed in light of mathematical induction.Furthermore,an actor-critic NN scheme is developed to approximate the control law and the proposed performance index function in the framework of ADP,and the stability of the closed-loop system is analyzed in view of the Lyapunov theory.Finally,the numerical simulation results are presented to demonstrate the effectiveness of the proposed control scheme.
文摘In this paper, an adaptive neural networks(NNs)tracking controller is proposed for a class of single-input/singleoutput(SISO) non-affine pure-feedback non-linear systems with input saturation. In the proposed approach, the original input saturated nonlinear system is augmented by a low pass filter.Then, new system states are introduced to implement states transformation of the augmented model. The resulting new model in affine Brunovsky form permits direct and simpler controller design by avoiding back-stepping technique and its complexity growing as done in existing methods in the literature.In controller design of the proposed approach, a state observer,based on the strictly positive real(SPR) theory, is introduced and designed to estimate the new system states, and only two neural networks are used to approximate the uncertain nonlinearities and compensate for the saturation nonlinearity of actuator. The proposed approach can not only provide a simple and effective way for construction of the controller in adaptive neural networks control of non-affine systems with input saturation, but also guarantee the tracking performance and the boundedness of all the signals in the closed-loop system. The stability of the control system is investigated by using the Lyapunov theory. Simulation examples are presented to show the effectiveness of the proposed controller.
基金National Key R&D Program of China under Grants No.2019YFC1509301.
文摘There are few studies on the dynamic-response mechanism of near-fault and far-field ground motions for large underground structures,especially for the branch joint of a utility tunnel(UT)and its internal pipeline.Based on the theory of a 3D viscous-spring artificial boundary,this paper deduced the equivalent nodal force when a P wave and an SV wave were vertically incident at the same time and transformed the ground motion into an equivalent nodal force using a self-developed MATLAB program,which was applied to an ABAQUS finite element model.Based on near-fault and far-field groundmotions obtained fromtheNGA-WEST2 database,the dynamic responses of a utility tunnel and its internal pipeline in different inputmechanisms of near-fault and far-field groundmotions were compared according to bidirectional input and tridirectional input,respectively.Generally,the damage to the utility tunnel caused by the near-fault ground motion was stronger than that caused by the far-field ground motion,and the vertical ground motion of near-fault ground motion aggravated the damage to the utility tunnel.In addition,the joint dislocation of the upper and lower three-way joints of the pipeline in the branch systemunder the seismic action led to local stress concentrations.In general,the branch system of the utility tunnel had good seismic performance to resist the designed earthquake action and protect the internal pipeline fromdamage during the rare earthquake.
基金supported by the National Natural Science Foundation of China(61921004,61520106009,U1713209,61973074)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘In this paper, we study the consensus problem for a class of linear multi-agent systems(MASs) with consideration of input saturation under the self-triggered mechanism. In the context of discrete-time systems, a self-triggered strategy is developed to determine the time interval between the adjacent triggers. The triggering condition is designed by using the current sampled consensus error. Furthermore, the consensus control protocol is designed by means of a state feedback approach. It is shown that the considered multi-agent systems can reach consensus with the presented algorithm. Some sufficient conditions are proposed in the form of linear matrix inequalities(LMIs) to show the positively invariant property of the domain of attraction(DOA). Moreover, some sufficient conditions of controller synthesis are provided to enlarge the volume of the DOA and obtain the control gain matrix. A numerical example is simulated to demonstrate the effectiveness of the theoretical analysis results.
基金supported in part by the National Key Research and Development Program(2018YFA0702202)in part by the Leadingedge Technology Program of Jiangsu National Science Foundation(BK20202011)in part by the Research Grants of the Nanjing University of Posts and Telecommunications(NY220158,NY220177)。
文摘This paper considers the leader-following consensus for a class of nonlinear switched multi-agent systems(MASs)with non-strict feedback forms and input saturations under unknown switching mechanisms.First,in virtue of Gaussian error functions,the saturation nonlinearities are represented by asymmetric saturation models.Second,neural networks are utilized to approximate some unknown packaged functions,and the structural property of Gaussian basis functions is introduced to handle the non-strict feedback terms.Third,by using the backstepping process,a common Lyapunov function is constructed for all the subsystems of the followers.At last,we propose an adaptive consensus protocol,under which the tracking error under arbitrary switching converges to a small neighborhood of the origin.The effectiveness of the proposed protocol is illustrated by a simulation example.
基金supported by the National Natural Science Foundation of China(61703427).
文摘In recent years,with the continuous development of multi-agent technology represented by unmanned aerial vehicle(UAV)swarm,consensus control has become a hot spot in academic research.In this paper,we put forward a discrete-time consensus protocol and obtain the necessary and sufficient conditions for the second-order consensus of the second-order multi-agent system with a fixed structure under the condition of no saturation input.The theoretical derivation verifies that the two eigenvalues of the Laplacian of the communication network matrix and the sampling period have an important effect on achieving consensus.Then we construct and verify sufficient conditions to achieve consensus under the condition of input saturation constraints.The results show that consensus can be achieved if velocity,position gain,and sampling period satisfy a set of inequalities related to the eigenvalues of the Laplacian matrix.Finally,the accuracy and validity of the theoretical results are proved by numerical simulations.
