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design and fabrication of a full elastic sub-micron-Newton scale thrust measurement system for plasma micro thrusters

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Plasma Science and Technology 2021年第10期23卷 29-39页

作者： Zhongkai Zhang Guanrong Hang Jiayun Qi Zun Zhang Zhe Zhang Jiubin Liu Wenjiang Yang Haibin Tang School of Space and Environment Beihang UniversityBeijing 100191People's Republic of China Shanghai Institute of Space Propulsion Shanghai Engineering Research Center of Space EngineShanghai 201112People's Republic of China School of Astronautics Beihang UniversityBeijing 100191People's Republic of China The Institute of Space Systems University of StuttgartStuttgart D-70569GermanyBeijing 100083People's Republic of China Key Laboratory of Spacecraft Design Optimization&Dynamic Simulation Technologies Ministry of EducationBeijing 100083People's Republic of China Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information TechnologyBeijing 100083People’s Republic of China

In this work,a force measurement system is proposed to measure the thrust of plasma microthruster with thrust magnitude ranging from sub-micro-Newtons to hundreds *** thrust measurement system uses an elastic torsional pendulum structure with a capacitance sensor to measure the displacement,which can reflect the position change caused by the applied force perpendicular to the pendulum *** the open-loop mode,the steady-state thrust or the impulse of the plasma micro-thruster can be obtained from the swing of the pendulum,and in the closed-loop mode the steady-state thrust can be obtained from the feedback force that keeps the pendulum at a specific *** thrust respond of the system was calibrated using an electrostatic weak force generation *** results show that the system can measure a thrust range from 0 to 200μN in both open-loop mode and closed-loop mode with a thrust resolution of 0.1μN,and the system can response to a pulse bit at the magnitude of 0.1 m N s generated by a micro cathode arc *** background noise of the closed-loop mode is lower than that of the open-loop mode,both less than 0.1 m N/Hz in the range of 10 mHz to 5 Hz.

关键词： plasma thruster micro-thrust measurement torsional pendulum

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Infrared image deturbulence restoration using degradation parameter-assisted wide & deep learning

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Infrared Physics & Technology 2025年 150卷

作者： Yi Lu Yadong Wang Xingbo Jiang Xiangzhi Bai Image Processing Center Beihang University Beijing 102206 China The State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 China Beijing Advanced Innovation Center for Biomedical Engineering Beihang University Beijing 100083 China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technology Ministry of Education Beihang University Beijing 102206 China

Infrared images captured under turbulent conditions are often degraded by complex geometric distortions and blurring, which substantially compromise image clarity and subsequent analysis. In this paper, we recast the infrared deturbulence problem as a more general image restoration task and propose a parameter assisted image restoration method that leverages degradation prior information from the turbulent infrared images. Specifically, we propose an ingenious and efficient multi-frame image restoration network (DparNet) with wide & deep architecture, which integrates degraded images and prior knowledge of degradation to reconstruct images with ideal clarity and stability. The degradation prior is directly learned from degraded images in form of key degradation parameter matrix, with no requirement of any off-site knowledge. The wide & deep architecture in DparNet enables the learned parameters to directly modulate the final restoring results, boosting spatial & intensity adaptive image restoration. We demonstrate the proposed method on infrared image deturbulence by constructing a dedicated dataset of 49,744 images to rigorously evaluate its performance under challenging turbulence degradation. To further validate the generality of our approach, a supplementary visible image denoising experiment was also conducted on a larger dataset containing 109,536 images. The experimental results show that our DparNet significantly outperform SoTA methods in restoration performance and network efficiency. More importantly, by utilizing the learned degradation parameters via wide & deep learning, we can improve the PSNR of image restoration by 0.6 ∼ 1.1 dB with less than 2% increasing in model parameter numbers and computational complexity. Our work suggests that degraded images may hide key information of the degradation process, which can be utilized to boost spatial & intensity adaptive image restoration.

关键词： Degradation prior Infrared image deturbulence Parameter-assisted restoration Wide and deep network

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A Ply-By-Ply Discretized 2D FEA Approach with the Integrated XFEM-CE Strategy for Predicting Multiple Failures in Laminated Composite Structures

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Computer Modeling in Engineering & Sciences 2019年第7期120卷 215-234页

作者： Yana Wang Ruodi Jia Fengrui Liu School of Astronautics Beihang UniversityBeijing100191China Aeronautical Material Testing Research Center AECC Beijing Institute of Aeronautical MaterialsBeijing100095China Beijing Key Laboratory of Aeronautical Material Testing and Evaluation Beijing100095China Key Laboratory of Aeronautical Material Testing and Evaluation Aero Engine Corporation of ChinaBeijing100095China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Minisitry of EducationBeihang UniversityBeijing100191China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an710049China.

Delamination and matrix cracking are two common failure mechanisms in composite structures,and are usually coupled with each other,leading to multiple failures *** paper proposed a fast damage prediction methodology for composite laminated structures based on the ply-by-ply 2D(two dimensional)FE model of composite laminates in the transverse *** layer-wise 2D FE model was firstly used in conjunction with the integrated XFEM/CE strategy,which simulated the interface delamination with cohesive elements and the intra-ply matrix crack with XFEM(extended finite element method).To realize ply-by-ply 2D FE(finite element)modeling of composite laminates,two 2D material models were developed based on the plane stress assumption and plane strain assumption,respectively.A general crack propagation scheme was developed in the framework of the integrated XFEM-CE *** the 2D material model based on the plane strain assumption,a ply-by-ply discretized 2D FEA procedure was conducted for an out-of-plane composite Pi joint under the static tensile *** predicted load-displacement response and damage evolution process showed good agreement with the experimental results,which verified the proposed approach.

关键词： Composites laminate strength finite element analysis

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Linearization of the dynamics of closed-chain mechanical systems

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MECHANICS OF STRUCTURES AND MACHINES 1997年第1期25卷 21-40页

作者： Lin, TC Yae, KH [a] The Center for Simulation and Design Optimization Department of Mechanical Engineering The University of Iowa Iowa City Iowa U.S.A

This paper presents an analytical-numerical method for linearizing the equations of motion of mechanical systems with dosed chains. The algorithm developed here linearizes basic recursive kinematic relationships and then applies the chain rule to the derivation of the equations of motion under the framework of recursive formulation. This method can be incorporated into the formulation of recursive equations of motion for general multibody dynamic systems to handle large-scale systems. The method is directly applicable to system Jacobian matrix computation. Since the proposed algorithm uses no numerical differentiation, its accuracy is comparable to a symbolic, closed-form linearization. Moreover, without needing repetition computation in search of proper perturbation quantity, this method is computationally more efficient than the finite difference method.

关键词： Mechanisms

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On the skew-symmetric property of the Newton-Euler formulation for open-chain robot manipulators

On the skew-symmetric property of the Newton-Euler formulati...

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American Control Conference (ACC)

作者： Hong-Chin Lin Tsung-Chieh Lin K.H. Yae Center for Simulation and Design Optimization Department of Mechanical Engineering University of Iowa Iowa IA USA

This paper proposes a form of the Coriolis-centrifugal matrix that, together with the inertia (or mass) matrix, satisfies the skew-symmetric property that is required by a class of regressor-based adaptive control. Such a matrix has been identified in Lagrange-Euler formulation, but not in Newton-Euler formulation. The paper shows how this matrix is separated out from a recursive Newton-Euler formulation for open-chain robot manipulators.

关键词： Equations Robot kinematics Manipulator dynamics Adaptive control Lagrangian functions Torque Mechanical factors Acceleration Programmable control Dynamic programming

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USE OF SPATIAL VELOCITY IN RECURSIVE DYNAMIC FORMULATION OF A MANIPULATOR DRIVEN BY HARMONIC DRIVES

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MECHANICS OF STRUCTURES AND MACHINES 1994年第3期22卷 343-370页

作者： LIN, TC YAE, KH [a]THE CENTER FOR SIMULATION AND DESIGN OPTIMIZATION DEPARTMENT OF MECHANICAL ENGINEERING THE UNIVERSITY OF IOWA IOWA CITY IOWA U.S.A.

The recursive Newton-Euler dynamic formulation is used to derive the equations of motion of a manipulator with harmonic drives. The derivation is general, in that the harmonic drive is viewed as a separate body that forms a kinematically closed chain with two contiguous links, leading to a comprehensive dynamic model. The harmonic drive is modeled as a flexible and rigid gear with a high gear reduction ratio. Under different modeling assumptions, the effects of gear flexibility and dynamic coupling are examined using a seven-degree-of-freedom manipulator.

关键词： Manipulators

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NUMERICAL-ANALYSIS OF THE KINEMATIC DEXTERITY OF MECHANISMS

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JOURNAL OF MECHANICAL design 1994年第1期116卷 119-126页

作者： YANG, FC HAUG, EJ Center for Simulation and Design Optimization of Mechanical Systems Department of Mechanical Engineering The University of Iowa Iowa City IA 52242

A general approach to numerical analysis of the kinematic dexterity of mechanisms is presented. Dextrous workspace problems are first defined and illustrated with examples. Composite workspaces are introduced to characterize both positioning and orienting capabilities of mechanisms. A numerical formulation and computer implementation that incorporates computer graphics and a numerical algorithm for solving systems of nonlinear equations are presented. Using the composite workspace formulation and the computer implementation, numerical techniques for dextrous workspace analysis are presented. Examples are given to illustrate the techniques developed.

关键词： Computers Kinematics Nonlinear equations Numerical analysis Composite materials Algorithms

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NUMERICAL-ANALYSIS OF THE KINEMATIC WORKING CAPABILITY OF MECHANISMS

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JOURNAL OF MECHANICAL design 1994年第1期116卷 111-118页

作者： YANG, FC HAUG, EJ Center for Simulation and Design Optimization of Mechanical Systems Department of Mechanical Engineering The University of Iowa Iowa City IA 52242

A broadly applicable approach for numerical analysis of the kinematic working capability of mechanisms is presented. Composite workspaces are introduced to represent position and orientation capabilities of mechanisms, both individually and together. Numerical methods for solving systems of kinematic constraint equations, using a moving-frame algorithm and equations that characterize the workspace boundary are developed. Two analytic methodologies, comparison and incorporation methods, are presented to determine whether the workspace of a mechanism satisfies design requirements. An experimental computer program for workspace analysis that incorporates a numerical solver and computer graphics for visualization on a high speed graphics workstation is outlined. The feasible positioning space of a Stewart platform that is subject to orientation constraints is computed, to illustrate the use of this approach.

关键词： Computers Kinematics design Numerical analysis Composite materials Visualization Computer software Algorithms

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RECURSIVE LINEARIZATION OF MULTIBODY DYNAMICS AND APPLICATION TO CONTROL design

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JOURNAL OF MECHANICAL design 1994年第2期116卷 445-451页

作者： LIN, TC YAE, KH Center for Simulation and Design Optimization Department of Mechanical Engineering The University of Iowa Iowa City IA 52242

The nonlinear equations of motion in multibody dynamics pose a difficult problem in linear control design. It is therefore desirable to have linearization capability in conjunction with a general-purpose multibody dynamics modeling technique. A new computational method for linearization is obtained by applying a series of first-order analytical approximations to the recursive kinematic relationships. The method has proved to be computationally more efficient. It has also turned out to be more accurate because the analytical perturbation requires matrix and vector operations by circumventing numerical differentiation and other associated numerical operations that may accumulate computational error.

关键词： Errors Computational methods design Kinematics Modeling Nonlinear equations Multibody dynamics Approximation

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Linearization of multibody dynamic systems using automatic differentiation (AD) tools

Linearization of multibody dynamic systems using automatic d...

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ASME 1993 design Technical Conferences, DETC 1993

作者： Un, Tsung-Chieh Center for Simulation and Design Optimization Department of Mechanical Engineering The University of Iowa Iowa CityIA United States

ISBN: (纸本)9780791811818

This paper presents an automatic method to linearize the dynamics of multibody systems that are modeled through a recursive approach. The first-order approximation of the nonlinear dynamic systems is obtained by the use of an automatic differentiation (AD) tool (GRESS) and a 9,700 lines Fortran model for the dynamics. The efficiency and accuracy of this AD implementation is shown by two examples: a five-bar closed-chain robot manipulator and a 18 degrees of freedom tractor-trailer. This study successfully demonstrates how to create a general-purpose numerical tool that can provide accurate solutions and derivatives for multibody dynamic systems. © 1993 Proceedings of the ASME design Engineering Technical Conference.

关键词： Degrees of freedom (mechanics)

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