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Observer Design for A Class of Uncertain State-Delayed Nonlinear Systems
Junwei Lu,Chunmei Feng,Shengyuan Xu,Yuming Chu 대한전기학회 2006 International Journal of Control, Automation, and Vol.4 No.4
This paper deals with the observer design problem for a class of state-delayed nonlinear systems with or without time-varying norm-bounded parameter uncertainty. The nonlinearities under consideration are assumed to satisfy the global Lipschitz conditions and appear in both the state and measured output equations. The problem we address is the design of a nonlinear observer such that the resulting error system is globally asymptotically stable. For the case when there is no parameter uncertainty, a sufficient condition for the solvability of this problem is derived in terms of linear matrix inequalities and the explicit formula of a desired observer is given. Based on this, the robust observer design problem for the case when parameter uncertainties appear is considered and the solvability condition is also given. Both of the solvability conditions obtained in this paper are delay-dependent. A numerical example is provided to demonstrate the applicability of the proposed approach.
Mixed H2/H∞ Control for a Class of Nonlinear Networked Control Systems
Yanqian Wang,Junwei Lu,Ze Li,Yuming Chu 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.3
In this paper, the mixed H2=H∞ control problem is investigated for a class of nonlinear discrete-time networkedcontrol systems with random network-induced delays, stochastic packet dropouts and probabilistic sensorfaults. The packet dropouts process is modeled as a homogeneous Markov chains taking values in a finite statespace. Network-induced delays occur in a random way with known upper bound. A set of stochastic variablesare exploited to describe sensor faults with different probabilistic density functions. By using a delay-dependentLyapunov functional, a mode-dependent mixed H2=H∞ controller is designed to guarantee both stochastic stabilityof the closed-loop system and the prescribed H2, H∞ control performances. Sufficient conditions for the existenceof the mixed H2=H∞ controller are presented in terms of a series of LMIs. If these LMIs are feasible, then the modedependentmixed H2=H∞ controller can be obtained. A numerical example is given to demonstrate the effectivenessof the developed method.
Fuzzy-PID controller for motion control of CFETR multi-functional maintenance platform
Li, Dongyi,Lu, Kun,Cheng, Yong,Zhao, Wenlong,Yang, Songzhu,Zhang, Yu,Li, Junwei,Wu, Huapeng Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.7
The motion control of the divertor maintenance system of the China Fusion Engineering Test Reactor (CFETR) was studied in this paper, in which CFETR Multi-Functional Maintenance Platform (MFMP) was simplified as a parallel robot for the convenience of theoretical analysis. In order to design the motion controller of parallel robot, the kinematics analysis of parallel robot was carried out. After that, the dynamic modeling of the hydraulic system was built. As the large variation of heavy payload on MFMP and highly nonlinearity of the system, A Fuzzy-PID controller was built for self-tuning PID controller parameters by using Fuzzy system to achieve better performance. In order to test the feasibility of the Fuzzy-PID controller, the simulation model of the system was built in Simulink. The results have showed that Fuzzy-PID controller can significantly reduce the angular error of the moving platform and provide the stable motion for transferring the divertor.
Li, Dongyi,Lu, Kun,Cheng, Yong,Zhao, Wenlong,Yang, Songzhu,Zhang, Yu,Li, Junwei,Shi, Shanshuang Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.11
The structure design of divertor Multi-Functional Maintenance Platform (MFMP) actuated by hydraulic system for China Fusion Engineering Test Reactor (CFETR) was introduced in this paper. The model of MFMP was established according to maintenance requirements. In this paper, Newton-Euler method and the improved virtual work principle were used, the equivalent driving force of each actuator was obtained through the equivalent Jacobian inverse matrix derived from velocity relationship among the components. The accuracy of the model was verified by ADAMS simulation. The stability control of the heavy-duty components driven by hydraulic cylinders based on Newton-Euler method and improved virtual work principle was established.
Measurement of TOF of fast neutrons with <sup>238</sup>U target
Li, Meng,Guan, Yuanfan,Lu, Chengui,Zhang, Junwei,Yuan, Xiaohua,Duan, Limin,Yang, Herun,Hu, Rongjiang,He, Zhiyong,Wei, Xianglun,Ma, Peng,Gan, Zaiguo,Yang, Chunli,Zhang, Hongbin,Chen, Liang,Qiu, Tianli Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6
We developed a Dual-PPACs detector for fast neutron measurements that consists of two sets of PPAC: conventional PPAC and fission PPAC. A<sup>238</sup>U(U<sub>3</sub>O<sub>8</sub>) coating is placed in the fission PPAC's anode, which is used as the neutrons conversion layer. An experiment was performed to measure neutron time-of-flight (TOF) in which <sup>252</sup>Cf spontaneous fission source was used. An excellent time resolution of 164ps has been observed at 6 mbar in isobutene gas. With the excellent time resolution of Dual-PPACs detector, exact neutron energy can be extracted from the timing measurement. The experimental detection efficiency was 1.9 × 10<sup>-7</sup>, consistent with the efficiency of 2.5 × 10<sup>-7</sup> given by a Geant4 simulation. Ultimately, the results show that the Dual-PPACs detector is a suitable candidate for measuring fast neutrons in the future CiADS system.
Xiaojing Qi,Wenhui Liu,Junwei Lu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.5
In this article, the observer-based adaptive finite-time prescribed performance control issue is studied for a category of nonlinear systems with external disturbances and input delay. The fuzzy logic systems are employed to model the unknown nonlinear terms in the system. The Pade approximation method is utilized to deal with the input delay problem. To estimate the unmeasurable states in the system, a fuzzy state observer is established. By using the finite-time Lyapunov control theory and the backstepping technique, a finite-time adaptive fuzzy controller is designed. The controller can guarantee that the tracking error converges to a prescribed region in a finite time and the boundedness of all signals in the closed-loop system. Finally, a simulation example is included to verify the validity and feasibility of the control method.
Metal Adsorbate-Induced Plasmon Damping in Gold Nanorods: The Difference Between Metals
Pengyu Xu,Xuxing Lu,Junwei Zhao,Yue Li,Sheng Chen,Junfei Xue,Weihui Ou,Song Han,YAPING DING,Weihai Ni 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.9
We presented a single particle study on the metal adsorbate-induced plasmon damping in Au nanorods (AuNRs) through adsorbing clusters of different metals including Pt, Au and Ag. AuNRs with different longitudinal surface plasmon resonance (LSPR) wavelength were measured and investigated individually. Linewidth broadening, plasmon shift and reduction of plasmonic resonance of single AuNRs were studied and compared between Pt, Au and Ag adsorbates. The measured linewidths perfectly match the theoretical predictions of the billiard model with increased scattering coefficients resulted from the metal adsorbates. The results indicate that the plasmon damping in case of Ag is significantly weaker than Pt and Au, which can be attributed to longer relaxation time of free electrons in Ag and therefore less loss of the oscillating plasmon electrons. In contrast to the red shift observed from Au and Pt, blue shift of the LSPR is observed in case of Ag. It suggests that plasmonic properties brought by the metal adsorbates can exert dramatic influence on the nanoparticle that is adsorbed with. We believe that our study not only provides important understanding on plasmon damping but pave the road for the fabrication of complex nanostructures with two or more metal elements.
Adaptive Prescribed Performance Output Regulation of Nonlinear Systems with Nonlinear Exosystems
Fujin Jia,Cui Lei,Junwei Lu,Yuming Chu 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.8
The paper studies the prescribed performance output regulation problem for a class of nonlinear uncertain strict-feedback systems which are driven by nonlinear exosystems. Fuzzy logic systems (FLSs) are used to approximate the unknown functions. A fuzzy adaptive observer is designed to estimate the system state. A fuzzy internal model is designed to reject disturbance. Simultaneously, a parameter-type Lyapunov function and L function are designed to ensure the prescribed performance of the system. As illustrated by example, the proposed prescribed performance fuzzy adaptive output feedback control scheme is shown to guarantee semi-globally uniformly ultimately bounded, and the dynamic performance and steady-state performance of the tracking error are dependent on the prescribed performance functions.
Yangchen Zhu,Xiao-Na Song,Mi Wang,Junwei Lu 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.2
In this paper, the problem of asynchronous H∞ filtering is discussed for discrete-time Takagi-Sugeno (T-S) fuzzy Markov jump systems (FMJSs) with randomly occurred quantization. The asynchrony refers to the situation that the plant state and the filter state belong to different local state space regions, and the randomly occurred quantization is introduced to describe the quantisation phenomenon appearing in a probabilistic way. The aim of this study is to design an asynchronous H∞ filter for discrete-time T-S FMJSs such that the resulting filtering error system satisfies H∞ disturbance attention performance and finite-time boundedness. Then, the gains of the filter are obtained by solving a set of linear matrix inequalities. Finally, three examples are utilized to illustrate the effectiveness of our proposed approach.
Xingru Li,Xiao-Na Song,Zhaoke Ning,Junwei Lu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.9
This paper is concerned with the quasi-synchronization problem for a class of hybrid coupled neuralnetworks with reaction diffusion, where the mismatched parameter and time-varying delay are considered in thesystem model. At first, a time-space sampled-data control is introduced, which not only effectively saves limitednetwork bandwidth compared to traditional control strategies, but also improves the cyber-security of communications. Next, based on the Lyapunov function method and inequality techniques, some sufficient conditions arederived to guarantee the quasi-synchronization of hybrid coupled neural networks with mismatched parameter andreaction-diffusion, and the convergence region of quasi-synchronization is derived using the improved Halanay’sinequality. Finally, the validity and practicability of the derived criteria are verified by three numerical examplesand an application example, respectively.