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Finite-Time Convergence Disturbance Rejection Control for a Flexible Timoshenko Manipulator

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IEEE/CAA Journal of Automatica Sinica 2021年第1期8卷 157-168页

作者： Zhijia Zhao zhijie liu the School of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou 510006China the School of Automation and Electrical Engineering University of Science and Technology Beijing(USTB)Beijing 100083 Shunde Graduate School of USTB Foshan 528300China

This paper focuses on a new finite-time convergence disturbance rejection control scheme design for a flexible Timoshenko manipulator subject to extraneous *** suppress the shear deformation and elastic oscillation,position the manipulator in a desired angle,and ensure the finitetime convergence of disturbances,we develop three disturbance observers(DOs)and boundary *** the derived DOs-based control schemes,the controlled system is guaranteed to be uniformly bounded stable and disturbance estimation errors converge to zero in a finite *** the end,numerical simulations are established by finite difference methods to demonstrate the effectiveness of the devised scheme by selecting appropriate parameters.

关键词： Disturbance observer disturbance rejection control finite-time convergence Timoshenko manipulator vibration control

Variational method based robust adaptive control for a guided spinning rocket

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Chinese Journal of Aeronautics 2021年第3期34卷 164-175页

作者： Zhongjiao Shi Liangyu Zhao zhijie liu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing 100083China

In this paper,a robust adaptive controller is designed for a guided spinning rocket,whose dynamics presents the characteristics of pitch-yaw cross coupling,fast time-varying aerodynamics parameters and wide flight ***,a coupled nonlinear six-degree-of-freedom equation of motion for a guided spinning rocket is developed,and the lateral acceleration motion is modeled as a control plant with time-varying matched uncertainties and unmodeled ***,a robust adaptive control method is proposed by combining Bregman divergence and variational method to achieve fast adaption and maintain bounded *** stability of the resulting closed-loop system is proved,and the ultimate bound and convergence rate are also ***,numerical simulations are performed for a single operating point and the whole flight trajectory to show the robustness and adaptability of the proposed method with respect to timevarying uncertainties and unmodeled dynamics.

关键词： Autopilot design Guided spinning rockets Robust adaptive control Second-order adaptive law Variational method

Modeling and adaptive control for a spatial flexible spacecraft with unknown actuator failures

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Science China(Information Sciences) 2021年第5期64卷 177-192页

作者： zhijie liu Zhiji HAN Zhijia ZHAO Wei HE Key Laboratory of Knowledge Automation for Industrial Processes of Ministry of Education School of Automation and Electrical Engineering Institute of Artificial IntelligenceUniversity of Science and Technology Beijing School of Mechanical and Electrical Engineering Guangzhou University Shunde Graduate School of University of Science and Technology Beijing

In this paper, we address simultaneous control of a flexible spacecraft’s attitude and vibrations in a three-dimensional space under input disturbances and unknown actuator failures. Using Hamilton’s principle, the system dynamics is modeled as an infinite dimensional system captured using partial differential equations. Moreover, a novel adaptive fault tolerant control strategy is developed to suppress the vibrations of the flexible panel in the course of the attitude stabilization. To determine whether the system energies,angular velocities and transverse deflections, remain bounded and asymptotically decay to zero in the case wherein the number of actuator failures is infinite, a Lyapunov-based stability analysis is conducted. Finally,extensive numerical simulations are performed to demonstrate the performance of the proposed adaptive control strategy.

关键词： adaptive control actuator failures infinite-dimensional systems flexible spacecraft fault tolerant control

Multifaceted function of YAP/TEAD on chromatin:prospects of‘A non-canonical role of YAP/TEAD is required for activation of estrogen-regulated enhancers in breast cancer’

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Journal of Molecular Cell Biology 2019年第12期11卷 1101-1103页

作者： Lizhen Chen zhijie liu Barshop Institute for Longevity and Aging Studies Department of Cell Systems and AnatomyThe University of Texas Health Science Center at San AntonioSan AntonioTX 78229USA Department of Molecular Medicine Mays Cancer CenterThe University of Texas Health Science Center at San AntonioSan AntonioTX 78229USA

Cellular function and behavior are controlled by various signals during development and disease progression in *** is important to understand how signals ultimately alter the function and structure of DNA regulatory elements,especially enhancers,causing the changes of gene expression *** average,each mature human cell harbors at least^100000 enhancers,but only a small percent of them have the function to activate gene *** instance,only^12%–18%of ERα-bound enhancers are active *** enhancers become functionally active is critical for our overall understanding of enhancer biology and gene *** are recognized by signaling-dependent DNA binding transcription factors(TFs),resulting in the recruitment of different enhancer activation components that allow distal enhancers to interact with their target promoters through chromatin looping(Plank and Dean,2014).Increasing evidence indicates that the recruitment and switching of enhancer components underlie enhancer activation and the deregulation in enhancer component or architecture profoundly alters signal-regulated transcriptional machineries,leading to developmental defects or diseases.

关键词： activation function instance

A side-effect-free method of reducing capacitance requirement for modular multilevel converters

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High Voltage 2022年第3期7卷 461-472页

作者： zhijie liu Kejun Li Jinyu Wang Liangzi Li School of Electrical Engineering Shandong UniversityJinanChina School of Electrical Engineering Xi'an Jiaotong UniversityXi'anChina

In modular multilevel converters(MMCs),the huge capacitor almost takes over half of the cost and weight of a submodule;as a result,the capacitance requirement reduction has attracted wide attention for using smaller ***,the existing methods have side effects,such as increasing the arm current and adding additional semi-conductors,which restrict their practical ***,a side-effect-free capacitance requirement reduction(CRR)method is proposed in this *** the method,the capacitor voltage can be decreased by injecting a specific dc signal into the original control system;and the specific dc signal is outputted from the proposed CRR controller according to the transmitted power of the *** ensuring the safe operation,the extent to which the capacitor voltage can be reduced is also studied;and an optimisation model is presented to obtain the minimum allowed capacitor voltage and the safety domain of *** effectiveness of the proposed method is proved by both simulation and *** results show that the capacitance requirement can be reduced by 32.4%without neither increasing the arm current nor adding additional semiconductors.

关键词： capacitance requirement effect

Output Constrained Adaptive Controller Design for Nonlinear Saturation Systems

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IEEE/CAA Journal of Automatica Sinica 2021年第2期8卷 441-454页

作者： Yongliang Yang zhijie liu Qing Li Donald C.Wunsch the Key Laboratory of Knowledge Automation for Industrial Processes of Ministry of Education School of Automation and Electrical EngineeringUniversity of Science and Technology BeijingBeijing 100083China the Department of Electrical and Computer Engineering Missouri University of Science and TechnologyRollaMO 65409 USA

This paper considers the adaptive neuro-fuzzy control scheme to solve the output tracking problem for a class of strict-feedback nonlinear *** asymmetric output constraints and input saturation are *** asymmetric barrier Lyapunov function with time-varying prescribed performance is presented to tackle the output-tracking error constraints.A high-gain observer is employed to relax the requirement of the Lipschitz continuity about the nonlinear *** avoid the"explosion of complexity",the dynamic surface control(DSC)technique is employed to filter the virtual control signal of each *** deal with the actuator saturation,an additional auxiliary dynamical system is *** is theoretically investigated that the parameter estimation and output tracking error are semi-global uniformly ultimately *** simulation examples are conducted to verify the presented adaptive fuzzy controller design.

关键词： Asymmetric barrier Lyapunov function input saturation Nussbaum function time-varying prescribed performance

Disturbance Observer Based Boundary Control of a Flexible Manipulator With Input Saturation 36

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Disturbance Observer Based Boundary Control of a Flexible Ma...

Theoretical Analysis of Bearing Capacity of Shallowly Embeded Rectangular Footing of Marine Structures

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作者： zhijie liu Jinkun liu School of Automation Science and Electrical Engineering Beihang University

ISBN: (纸本)9781538629185

In this study, we consider anti-windup design as one of the approaches for the boundary control problem of a flexible manipulator subject to input saturation and input disturbances. The dynamics of the system are represented by partial differential equation（PDE）. One of the key contributions of this study is that using singular perturbation approach the PDE model is divided into two simpler subsystems and a disturbance observer with exponential error convergence is proposed. In addition, based on the disturbance observer and decoupled PDE model, a boundary control scheme is designed to regulate angular position and suppress elastic vibration simultaneously. The proposed control scheme allows the application of smooth hyperbolic functions which satisfy physical conditions and input restrictions can easily be realized. Numerical simulations demonstrate the effectiveness of the proposed scheme.

关键词： Boundary control input saturation singular perturbation disturbance observer

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Journal of Ocean University of China 2019年第1期18卷 123-132页

作者： ZHANG Qiyi WU Shaoxuan WU Liangpeng liu zhijie Department of Ocean Engineering College of Engineering Ocean University of China Key Laboratory of Ocean Engineering of Shandong Province

In this paper, the finite element analysis software ABAQUS is used to analyze the ultimate bearing capacity of three-dimensional rectangular footing of marine structures. The deformation law and the failure mode of homogeneous seabed soil beneath the rectangular footing are analyzed in detail. According to the equivalent plastic strain of soil under rectangular footing, an allowable velocity field of homogeneous seabed soil is reasonably constructed. Based on the plastic limit analysis theory of soil mass and by using the Mohr-Coulomb yield criterion, an upper bound solution of the ultimate bearing capacity of three-dimensional rectangular footing on general homogeneous seabed soil is derived, and a correction factor of ultimate bearing capacity of three-dimensional rectangular footing is given. To verify the rationality and applicability of this theoretical solution, some numerical solutions are achieved using the general-purpose FEM analysis package ABAQUS, and comparisons are made among the derived upper bound solution, the solution of Vesic, and the solution of Salgado et al. The results indicate that the upper bound solution of the three-dimensional shallowly embedded rectangular footing proposed in this paper is accurate in calculating the bearing capacity of homogeneous seabed soil. For undrained saturated clay foundation and sandy foundation with smaller internal friction angle, this upper bound solution can evaluate the ultimate bearing capacity of rectangular footing; with the gradual increase of the internal friction angle of the soil, the ultimate bearing capacity of the proposed upper bound solution is slightly higher than that of the rectangular footing.

关键词： upper bound analysis velocity field ultimate bearing capacity rectangular footing ABAQUS

Modeling and Adaptive Neural Network Control for a Soft Robotic Arm With Prescribed Motion Constraints

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IEEE/CAA Journal of Automatica Sinica 2023年第2期10卷 501-511页

作者： Yan Yang Jiangtao Han zhijie liu Zhijia Zhao Keum-Shik Hong the School of Intelligence Science and Technology University of Science and Technology BeijingBeijing 10083 the Institute of Artificial Intelligence University of Science and Technology BeijingBeijing 100083China IEEE the School of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou 510006China the School of Mechanical Engineering Pusan National UniversityBusan 46241South Korea

This paper presents a dynamic model and performance constraint control of a line-driven soft robotic *** dynamics model of the soft robotic arm is established by combining the screw theory and the Cosserat *** unmodeled dynamics of the system are considered,and an adaptive neural network controller is designed using the backstepping method and radial basis function neural *** stability of the closed-loop system and the boundedness of the tracking error are verified using Lyapunov *** simulation results show that our approach is a good solution to the motion constraint problem of the line-driven soft robotic arm.

关键词： Adaptive control cosserat theory prescribed motion constraints soft robotic arm