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PGOPO Approach to Design Linear Servomechanism of Time-Varying Systems with Time-Delay
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作者 吴斌 程鹏 钟宜生 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2001年第2期88-93,共6页
Based on a new linear, continuous and bounded operator (PGOPO), a more effective approach and optimal control algorithm than by the block-pulse functions and Walsh functions to design the linear servomechanism of time... Based on a new linear, continuous and bounded operator (PGOPO), a more effective approach and optimal control algorithm than by the block-pulse functions and Walsh functions to design the linear servomechanism of time-varying systems with time-delay is proposed in the paper. By means of the operator, the differential equation is transferred to a more explicit algebraic form which is much easier than the numerical integration of nonlinear TPBVP derived from Pantryagin's maximum principle method. Furthermore, the method is established strictly based on the theory of convergence in the mean square and it is convenient and simple in computation. So the method can be applied to industry control and aeronautics and astronautics field which is frequently mixed with time varying and time delay. Some illustrative numerical examples are interpreted to support the technique. 展开更多
关键词 ALGORITHMS Convergence of numerical methods Differential equations Mathematical operators POLYNOMIALS time varying systems Walsh transforms
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Dynamic Stability Analysis of Linear Time-varying Systems via an Extended Modal Identification Approach 被引量:2
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作者 Zhisai MA Li LIU +3 位作者 Sida ZHOU Frank NAETS Ward HEYLEN Wim DESMET 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2017年第2期459-471,共13页
The problem of linear time-varying(LTV) system modal analysis is considered based on time-dependent state space representations, as classical modal analysis of linear time-invariant systems and current LTV system mo... The problem of linear time-varying(LTV) system modal analysis is considered based on time-dependent state space representations, as classical modal analysis of linear time-invariant systems and current LTV system modal analysis under the "frozen-time" assumption are not able to determine the dynamic stability of LTV systems. Time-dependent state space representations of LTV systems are first introduced, and the corresponding modal analysis theories are subsequently presented via a stabilitypreserving state transformation. The time-varying modes of LTV systems are extended in terms of uniqueness, and are further interpreted to determine the system's stability. An extended modal identification is proposed to estimate the time-varying modes, consisting of the estimation of the state transition matrix via a subspace-based method and the extraction of the time-varying modes by the QR decomposition. The proposed approach is numerically validated by three numerical cases, and is experimentally validated by a coupled moving-mass simply supported beam exper- imental case. The proposed approach is capable of accurately estimating the time-varying modes, and provides anew way to determine the dynamic stability of LTV systems by using the estimated time-varying modes. 展开更多
关键词 Linear time·varying systems · Extended modal identification · Dynamic stability analysis · time·varying modes
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Nonlinear Time-Varying Systems Identification Using Basis Sequence Expansions Combined with Neural Networks
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作者 顾成奎 王正欧 孙雅明 《Transactions of Tianjin University》 EI CAS 2003年第1期71-74,共4页
A new method for identifying nonlinear time varying systems with unknown structure is presented. The method extends the application area of basis sequence identification. The essential idea is to utilize the learning ... A new method for identifying nonlinear time varying systems with unknown structure is presented. The method extends the application area of basis sequence identification. The essential idea is to utilize the learning and nonlinear approximating ability of neural networks to model the non linearity of the system, characterize time varying dynamics of the system by the time varying parametric vector of the network, then the parametric vector of the network is approximated by a weighted sum of known basis sequences. Because of black box modeling ability of neural networks, the presented method can identify nonlinear time varying systems with unknown structure. In order to improve the real time capability of the algorithm, the neural network is trained by a simple fast learning algorithm based on local least squares presented by the authors. The effectiveness and the performance of the method are demonstrated by some simulation results. 展开更多
关键词 nonlinear time varying systems IDENTIFICATION basis sequence expansions neural networks
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Delay and Its Time-derivative Dependent Robust Stability of Uncertain Neutral Systems with Saturating Actuators 被引量:1
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作者 Fatima El Haoussi El Houssaine Tissir 《International Journal of Automation and computing》 EI 2010年第4期455-462,共8页
This note concerns the problem of the robust stability of uncertain neutral systems with time-varying delay and saturating actuators. The system considered is continuous in time with norm bounded parametric uncertaint... This note concerns the problem of the robust stability of uncertain neutral systems with time-varying delay and saturating actuators. The system considered is continuous in time with norm bounded parametric uncertainties. By incorporating the free weighing matrix approach developed recently, some new delay-dependent stability conditions in terms of linear matrix inequalities (LMIs) with some tuning parameters are obtained. An estimate of the domain of attraction of the closed-loop system under a priori designed controller is proposed. The approach is based on a polytopic description of the actuator saturation nonlinearities and the Lyapunov- Krasovskii method. Numerical examples are used to demonstrate the effectiveness of the proposed design method. 展开更多
关键词 Actuator saturation neutral systems unccrtainty delay-dependent condition linear matrix inequality (LMI) time varying delay systems.
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Generalization of integral inequalities and (c_1,c_1) stability of neutral differential equations with time-varying delays
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作者 Shuli Guo Lina Han 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2017年第2期347-360,共14页
A uniform stability analysis is developed for a type of neutral delays differential equations which depend on more general nonlinear integral inequalities. Many original investigations and results are obtained. Firstl... A uniform stability analysis is developed for a type of neutral delays differential equations which depend on more general nonlinear integral inequalities. Many original investigations and results are obtained. Firstly, generations of two integral nonlinear inequalities are presented, which are very effective in dealing with the complicated integro-differential inequalities whose variable exponents are greater than zero. Compared with existed integral inequalities, those proposed here can be applied to more complicated differential equations, such as time-varying delay neutral differential equations. Secondly, the notions of (ω, Ω) uniform stable and (ω, Ω) uniform asymptotically stable, especially (c1, c1) uniform stable and (c1, c1) uniform asymptotically stable, are presented. Sufficient conditions on about (c1, c1) uniform stable and (c1, c1) uniform asymptotically stable of time-varying delay neutral differential equations are established by the proposed integral inequalities. Finally, a complex numerical example is presented to illustrate the main results effectively. The above work allows to provide further applications on the proposed stability analysis and control system design for different nonlinear systems. © 2017 Beijing Institute of Aerospace Information. 展开更多
关键词 Control system stability Differential equations Nonlinear equations time delay time varying control systems
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Adaptive Robust Control for a Class of Uncertain MIMO Non-affine Nonlinear Systems 被引量:9
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作者 Longsheng Chen Qi Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI 2016年第1期105-112,共8页
In this paper, the adaptive robust tracking control scheme is proposed for a class of multi-input and multi-output (MIMO) non-affine systems with uncertain structure and parameters, unknown control direction and unkno... In this paper, the adaptive robust tracking control scheme is proposed for a class of multi-input and multi-output (MIMO) non-affine systems with uncertain structure and parameters, unknown control direction and unknown external disturbance based on backstepping technique. The MIMO non-affine system is first transformed into a time-varying system with strict feedback structure using the mean value theorem, and then the bounded time-varying parameters are estimated by adaptive algorithms with projection. To handle the possible 'controller singularity' problem caused by unknown control direction, a Nussbaum function is employed, and the dynamic surface control (DSC) method is applied to solve the problem of 'explosion of complexity' in backstepping control. It is proved that the proposed control scheme can guarantee that all signals of the closed-loop system are bounded through Lyapunov stability theorem and decoupled backstepping method. Simulation results are presented to illustrate the effectiveness of the proposed control scheme. © 2014 Chinese Association of Automation. 展开更多
关键词 Adaptive algorithms BACKSTEPPING Closed loop control systems Closed loop systems FUNCTIONS Nonlinear systems Robust control time varying systems Uncertainty analysis
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ELAPSED TIME OF PERIODIC MOTION WITH NEGATIVE DAMPING
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作者 李怡平 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1992年第8期719-723,共5页
An initially periodic motion is gradually raised out of the potential well by the effect of negative damping. The elapsed time when the motion ceases to be periodic is obtained by multiple variable expansions. An exam... An initially periodic motion is gradually raised out of the potential well by the effect of negative damping. The elapsed time when the motion ceases to be periodic is obtained by multiple variable expansions. An example of a strictly nonlinear system shows the result has a good approximation and is easy to calculate. 展开更多
关键词 Approximation theory DAMPING Mathematical models Nonlinear equations Numerical analysis Perturbation techniques time varying systems
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Adaptive Control of MIMO Mechanical Systems with Unknown Actuator Nonlinearities Based on the Nussbaum Gain Approach 被引量:4
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作者 Ci Chen Zhi Liu +2 位作者 Yun Zhang C.L.Philip Chen Shengli Xie 《IEEE/CAA Journal of Automatica Sinica》 EI 2016年第1期26-34,共9页
This paper investigates MIMO mechanical systems with unknown actuator nonlinearities. A novel Nussbaum analysis tool for MIMO systems is established such that unknown time-varying control coefficients are tackled. In ... This paper investigates MIMO mechanical systems with unknown actuator nonlinearities. A novel Nussbaum analysis tool for MIMO systems is established such that unknown time-varying control coefficients are tackled. In contrast to existing literatures on continuous-time systems, the newly-developed Nussbaum tool focuses on extending the traditional Nussbaum result from one dimensional case to the multiple one. Specifically, not only the multiple unknown input coefficients are extended to the time-varying, but also the limitation of the prior knowledge of coefficients' upper and lower bounds is removed. Furthermore, an adaptive robust controller associated with the proposed tool is presented. The asymptotic tracking of MIMO mechanical systems is guaranteed with the help of the Lyapunov Theorem. Finally, a simulation example is provided to examine the validity of the proposed scheme. © 2014 Chinese Association of Automation. 展开更多
关键词 Actuators Adaptive control systems Control nonlinearities Mechanical actuators MECHANICS MIMO systems time varying control systems
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A New Criterion for Stability of Large-Scale Systems with Delay
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作者 周少武 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2001年第4期59-65,共7页
A simple criterion for delay-independent stability of large-scale linear time-varying systems is deduced by employing a type of Lyapunov function. The notable features of the results in this paper are its simplicity a... A simple criterion for delay-independent stability of large-scale linear time-varying systems is deduced by employing a type of Lyapunov function. The notable features of the results in this paper are its simplicity and efficiency in testing the stability large-scale linear time-varying systems. Some illustrative examples are given to demonstrate the advantages of the obtained results over those in literature. 展开更多
关键词 Delay control systems Linear control systems Lyapunov methods System stability time varying control systems
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Robust H_∞ Stabilization of Uncertain Linear Time-Delay System with Delayed/Undelayed State Feedback Controllers
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作者 陈万义 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2001年第4期71-76,共6页
This paper focuses on the H∞ controller design for linear systems with time-varying delays and norm-bounded parameter perturbations in the system state and control/disturbance. On the existence of delayed/undelayed f... This paper focuses on the H∞ controller design for linear systems with time-varying delays and norm-bounded parameter perturbations in the system state and control/disturbance. On the existence of delayed/undelayed full state feedback controllers, we present a sufficient condition and give a design method in the form of Riccati equation. The controller can not only stabilize the time-delay system, but also make the H∞ norm of the closed-loop system be less than a given bound. This result practically generalizes the related results in current literature. 展开更多
关键词 Closed loop control systems Feedback control Linear control systems Perturbation techniques Riccati equations Robustness (control systems) State feedback System stability time varying control systems Uncertain systems
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Analysis of Linear Time-varying Systems via Haar Wavelet
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作者 刘湘黔 张霖 《Tsinghua Science and Technology》 SCIE EI CAS 1999年第1期43-45,共3页
In this paper Haar wavelet integral operational matrices are introduced and then applied to analyse linear time varying systems. The method converts the original problem to solving linear algebraic equations. Hence, ... In this paper Haar wavelet integral operational matrices are introduced and then applied to analyse linear time varying systems. The method converts the original problem to solving linear algebraic equations. Hence, computational difficulties are considerably reduced. Based on the property of time frequency localization of Haar wavelet bases, the solution of a system includes both the frequency information and the time information. Other orthogonal functions do not have this property. An example is given, and the results are shown to be very accurate. 展开更多
关键词 Haar wavelet time varying systems orthogonal functions
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PERIODIC HEAT TRANSFER IN THE FINS WITH VARIABLE THERMAL PARAMETERS
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作者 杨翔翔 何宏舟 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1996年第2期169-180,共12页
The problem of one dimensional, nonstationary heat transfer was solved by the method of small parameter perturbation, thus, the partial differential equation was reduced to a system of ordinary differential equations.... The problem of one dimensional, nonstationary heat transfer was solved by the method of small parameter perturbation, thus, the partial differential equation was reduced to a system of ordinary differential equations. Then, the numerical method, i.e. the shooting method and superposition method was used to solve the system of ordinary differential equations. Finally, the influences of some parameters on temperature distribution, heat flux and fin efficiency were discussed. In addition to theoretical significance, the results are of practical significance for engineering design. 展开更多
关键词 Heat transfer Numerical methods Perturbation techniques time varying systems
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Mobile Robot Control Based on Dynamic Potential
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作者 Tianmiao, Wang Bo, Zhang +1 位作者 Zengren, Yuan Kezhong, He 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1992年第1期73-82,共10页
An efficient method is presented for implementing mobile robot perception-action behaviors, based on time varying environment potential field approach. First, in this paper, the concept of dynamic potential U(x,y,z,t)... An efficient method is presented for implementing mobile robot perception-action behaviors, based on time varying environment potential field approach. First, in this paper, the concept of dynamic potential U(x,y,z,t) is proposed for representing the environment of a mobile robot, and the form of U(x,y,z,t) is deduced, and then the velocity control of the vehicle with two wheel is directly calculated by transition function T of U(x,y,z,t). Finally, the perception-action layer is successfully implemented for avoiding collision, wandering, and integrating path planning and steering control on THMR-II (tsingHua university Mobile Robot system). Based on sonar array signals, the experimental results are given to show that THMR-II has better reflexive function, real-time obstacle avoidance, adaptability and robustness for complex environments. 展开更多
关键词 Control systems Sensory perception time varying systems Velocity control
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Haar Wavelet and Its Application in Optimal Control of Linear Time-invariant Systems
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作者 刘湘黔 张霖 《Tsinghua Science and Technology》 SCIE EI CAS 1999年第1期39-42,共4页
This paper uses Haar wavelet integral operational matrices to approximate the solution of the optimal control problem with quadratic performance measures. The method reduces the original problem to the solution of l... This paper uses Haar wavelet integral operational matrices to approximate the solution of the optimal control problem with quadratic performance measures. The method reduces the original problem to the solution of linear algebraic equations. Hence, the computational difficulties are considerably reduced. Since Haar wavelet bases cooperate time frequency localization, the system solution includes both frequency information and time information. Other orthogonal functions do not have this property. An example shows that the results are very accurate. 展开更多
关键词 Haar wavelet time varying systems optimal control
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Local Influence on the Error-Correction Variable in a Cointegrated System
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作者 Zhang, X. Yang, B. +1 位作者 Zhang, T. Zhang, S. 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2001年第3期1-8,共8页
The concept of cointegration describes an equilibrium relationship among a set of time-varying variables, and the cointegrated relationship can be represented through an error-correction model (ECM). The error-correct... The concept of cointegration describes an equilibrium relationship among a set of time-varying variables, and the cointegrated relationship can be represented through an error-correction model (ECM). The error-correction variable, which represents the short-run discrepancy from the equilibrium state in a cointegrated system, plays an important role in the ECM. It is natural to ask how the error-correction mechanism works, or equivalently, how the short-run discrepancy affects the development of the cointegrated system? This paper examines the effect or local influence on the error-correction variable in an error-correction model. Following the argument of the second-order approach to local influence suggested by reference [5], we develop a diagnostic statistic to examine the local influence on the estimation of the parameter associated with the error-correction variable in an ECM. An empirical example is presented to illustrate the application of the proposed diagnostic. We find that the short-run discre pancy may have strong influence on the estimation of the parameter associated with the error-correction model. It is the error-correction variable that the short-run discrepancies can be incorporated through the error-correction mechanism. 展开更多
关键词 Computer simulation Error correction Mathematical models Parameter estimation Program diagnostics Statistical methods time series analysis time varying control systems
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Finite time L_1 Approach for Missile Overload Requirement Analysis in Terminal Guidance 被引量:4
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作者 Ji Denggao,He Fenghua,Yao Yu Control and Simulation Center,Harbin Institute of Technology,Harbin 150080,China 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2009年第4期413-418,共6页
This article analyzes the problem about the missile overload requirement in a homing terminal guidance under various engagement scenarios. An augmented proportional navigation guidance (APNG) model is introduced on ... This article analyzes the problem about the missile overload requirement in a homing terminal guidance under various engagement scenarios. An augmented proportional navigation guidance (APNG) model is introduced on the basis of linear kinematics. To analyze the peak-to-peak performance of the terminal guidance system, a new finite time L1 performance measure for a linear time-varying (LTV) continuous system is proposed. Then, according to the idea of the adjoint system, a novel method for computing the L1 norm of a linear continuous system is first derived. Within the finite time L1 framework, the quantitative relation between the guidance loop dynamics and the maximum missile-target maneuver ratio is offered. This relation is expressed in the form of graphs and formulas that can be used to synthesize some of the major subsystem specifications for the missile guidance system. The illustrative examples show that a significant performance improvement is achieved with the proposed guidance loop dynamics. 展开更多
关键词 finite time Lx-induced norm performance time varying systems missile overload requirement terminal guidance
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Time-stretch analog-to-digital conversion with a photonic crystal fiber 被引量:2
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作者 滕云 余重秀 +3 位作者 苑金辉 陈静轩 金沧 许谦 《Optoelectronics Letters》 EI 2011年第2期143-146,共4页
All-optical analog-to-digital conversion (ADC) has been extensively researched to break through the inherently limited operating speed of electronic devices. In this paper, we use the photonic crystal fiber (PCF) for ... All-optical analog-to-digital conversion (ADC) has been extensively researched to break through the inherently limited operating speed of electronic devices. In this paper, we use the photonic crystal fiber (PCF) for time-stretch (TS) analog-to-digital (A/D) conversion system through generating low noise, linear chirp distribution and flat super-continuum (SC). Based on the radio frequency (RF) analog signal modulated to the linearly chirped super-continuum, the large-dispersion photonic crystal fiber is used for time-domain stretching. 展开更多
关键词 Analog to digital conversion Crystal whiskers Digital devices Electric converters Nonlinear optics Photonic crystals time varying systems
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Robust Adaptive Actuator Failure Compensation for a Class of Uncertain Nonlinear Systems 被引量:3
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作者 Mahnaz Hashemi Javad Askari +1 位作者 Jafar Ghaisari Marzieh Kamali 《International Journal of Automation and computing》 EI CSCD 2017年第6期719-728,共10页
This paper presents a robust adaptive state feedback control scheme for a class of parametric-strict-feedback nonlinear systems in the presence of time varying actuator failures. The designed adaptive controller compe... This paper presents a robust adaptive state feedback control scheme for a class of parametric-strict-feedback nonlinear systems in the presence of time varying actuator failures. The designed adaptive controller compensates a general class of actuator failures without any need for explicit fault detection. The parameters, times, and patterns of the considered failures are completely unknown. The proposed controller is constructed based on a backstepping design method. The global boundedness of all the closed-loop signals is guaranteed and the tracking error is proved to converge to a small neighborhood of the origin. The proposed approach is employed for a two-axis positioning stage system as well as an aircraft wing system. The simulation results show the correctness and effectiveness of the proposed robust adaptive actuator failure compensation approach. 展开更多
关键词 time varying actuator failure nonlinear systems robust adaptive control compensation backstepping design method
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PERIODIC BOUNDARY CONDITION IN SIMULATION OF TURBULENT FLOW 被引量:4
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作者 Zhou, Xiao-Quan Cao, Shu-You +1 位作者 Qu, Lun-Fu Wu, Yu-Lin 《Journal of Hydrodynamics》 SCIE EI CSCD 2002年第3期111-116,共6页
The simulations of the three-dimensional turbulent flows through hydraulic turbine components[1] were conducted based on the standard k-Ε turbulent model with body-fitted coordinates and staggering grid system. The S... The simulations of the three-dimensional turbulent flows through hydraulic turbine components[1] were conducted based on the standard k-Ε turbulent model with body-fitted coordinates and staggering grid system. The SIMPLEC algorithm was adopted in the numerical procedure. A new method to treat the periodic boundary condition was used. The calculated results of the new method were compared with those of traditional ones. These results indicate that the new method can give much better results, and can be used in simulating flow through rotational impellers. The presented method can be combined with alternative turbulent model or employed in large eddy simulation. 展开更多
关键词 Computer simulation Hydraulic turbines IMPELLERS Three dimensional time varying systems
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