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Fault-Tolerant Control for the Formation of Multiple Unknown Nonlinear Quadrotors via Reinforcement Learning ⁎

IFAC-PapersOnLine 2020年第2期53卷 2465-2470页

作者： Wanbing Zhao Hao Liu Frank L. Lewis Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies of Ministry of Education Beihang University Beijing 100191 P.R. China University of Texas at Arlington Research Institute University of Texas at Arlington Fort Worth Texas 76118 USA

In this paper, the fault-tolerant control problem for the formation of unknown quadrotor team with nonlinearities, couplings, and actuator faults in the dynamics is investigated. A distributed observer is designed to estimate the position references for each quadrotor. A hierarchical control scheme is constructed including a fault-tolerant position controller to achieve the desired formation and a fault-tolerant attitude controller to track the attitude references. Reinforcement learning algorithms are designed to learn the optimal control policies of the position and attitude controllers. simulation results are given to illustrate the effectiveness of the proposed controller.

关键词： Fault-tolerant control formation control reinforcement learning model-free quadrotor system

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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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design of a small-size retarding potential analyzer and a practice of plasma beam energy diagnosis

Design of a small-size retarding potential analyzer and a pr...

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IEEE International Conference on Plasma Science (ICOPS)

作者： X. Wu J. Qi Y. Wang J. Ren Z. Zhang G. Zhang H. Deng W. Wang H. Tang School of Energy and Power Engineering Beihang University Beijing China School of Space and Environment Beihang University Beijing China School of Astronautics Beihang University Beijing China Ministry of Education Key Laboratory of Spacecraft Design Optimization & Dynamic Simulation Technologies Beijing China

ISBN: (数字)9798350360912

ISBN: (纸本)9798350360929

To reduce the perturbation of the probe to the plasma beam, improve the spatial resolution of Ion Energy Distribution Function (IEDF) measurements, and adapt to the needs of miniaturized electric thruster diagnostics, a miniaturized Retarding Potential Analyzer (RPA) is designed. In this paper, based on the RPA design criteria, the mesh and spacing of the small-size grid are determined by analyzing the electron density, temperature, and sheath thickness in the plasma beam obtained from Langmuir probe measurements. In this way, a miniaturized three-grid RPA is designed with an overall size of less than 30 $\mathrm{mm} \times 20 \mathrm{~mm} \times 11 \mathrm{~mm}$. This RPA enables high spatial resolution and high accuracy measurement of IEDF in plasma beam with ion energy up to 800 eV and repeatability accuracy better than 0.5 eV. It has been applied to the diagnosis of ion energy in electric thruster beams. In this work, the spatial distributions of ion energy, plasma density, and electron temperature in the beams of the Kaufman ion source at different accelerating voltages and gas flow rates are measured using RPA and Langmuir single probe, and the axial distribution of ion energy and the evolution laws of the Kaufman ion source beam are analyzed.

关键词： Temperature measurement Voltage measurement Particle beam measurements Energy measurement Ion sources Plasmas Probes

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Physics-Informed Neural Networks for Solving Forward and Inverse Vlasov-Poisson Equation Via Fully Kinetic simulation

SSRN

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SSRN 2022年

作者： Zhang, Baiyi Cai, Guobiao Weng, Huiyan Wang, Weizong Liu, Lihui Zheng, Juntao He, Bijiao School of Astronautics Beihang University Beijing100191 China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Ministry of Education Beijing100191 China Aircraft and Propulsion Laboratory Ningbo Institute of Technology Beihang University Ningbo315832 China Baidu Inc. Beijing100094 China

The Vlasov-Poisson equation is one of the most fundamental models in plasma physics. It has been widely used in areas such as confined plasmas in thermonuclear research and space plasmas in planetary magnetospheres. In this study, we explore the feasibility of the physics-informed neural networks for solving forward and inverse Vlasov-Poisson equation (PINN-Vlasov). The PINN-Vlasov method employs a multilayer perceptron (MLP) to represent the solution of the Vlasov-Poisson equation. The training dataset comprises the randomly sampled time, space, and velocity coordinates and the corresponding distribution function. We generate training data using the fully kinetic PIC simulation rather than the analytical solution to the Vlasov-Poisson equation to eliminate the correlation between data and equations. The Vlasov equation and Poisson equation are concurrently integrated into the PINN-Vlasov framework using automatic differentiation and the trapezoidal rule, respectively. By minimizing the residuals between the predicted distribution function and labeled data, and the physically constrained residuals of the Vlasov-Poisson equation, the PINN-Vlasov method is capable of dealing with both forward and inverse problems. For forward problems, the PINN-Vlasov method can solve the Vlasov-Poisson equation accurately and more efficiently with given initial and boundary conditions than the traditional method. For inverse problems, the completely unknown electric field, initial and boundary conditions, and equation coefficients can be accurately predicted with the PINN-Vlasov method using only little particle distribution data. © 2022, The Authors. All rights reserved.

关键词： Inverse problems

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A Novel Poisson's Equation Domain Decomposition Solver for Particle-in-Cell simulation

SSRN

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SSRN 2023年

作者： Mao, Renfan Ren, Junxue Pan, Ruojian Chen, Zhiyuan Tang, Haibin School of Space and Environment Beihang University Beijing100083 China School of Astronautics Beihang University Beijing100083 China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Ministry of Education Beijing100083 China Laboratory of Space Environment monitoring and Information Processing Ministry of Industry and Information Technology Beijing100083 China

The solution of Poisson's equation is an essential step in electrostatic particle-in-cell simulation, and the strict limits of grid spacing and time step constraints make it important to find a high-performance algorithm. A novel algorithm for solving Poisson's equation is established in this paper. This algorithm is a non-iterative algorithm based on Schwartz iteration, suitable for solving the linear system with a fixed coefficient matrix, and can benefit from the repetition of equation coefficients. The solution of the linear system is ultimately transformed into a finite number of matrix-vector multiplication. The performance of the algorithm has been tested and compared with other common algorithms, demonstrating its practicality. © 2023, The Authors. All rights reserved.

关键词： Poisson equation

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Application of the view factor model on the particle-in-cell and Monte Carlo collision code

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Physical Review E 2020年第3期102卷 033311-033311页

作者： Ruojian Pan Junxue Ren Haibin Tang Shuai Cao Juan Li Zhe Zhang Jun Zhou Jinbin Cao School of Space and Environment Beihang University Beijing 100083 China School of Astronautics Beihang University Beijing 100083 China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Ministry of Education Beijing 100083 China Laboratory of Space Environment monitoring and Information Processing Ministry of Industry and Information Technology Beijing 100083 China National Key Laboratory of Science and Technology on Vacuum Technology & Physics Lanzhou Institute of Physics Lanzhou 730000 China School of Instrumentation and Optoelectronic Engineering Beihang University Beijing 100083 China

Particle-in-cell and Monte Carlo collision (PIC-MCC) has been widely adopted as a simulation method for electric propulsion. However, neutral atoms move much more slowly than other species, which can cause a serious reduction in simulation speed. In this work, we investigate the view factor model in combination with the PIC-MCC method and propose a method for simulating three-dimensional neutral atoms. The accuracy of the PIC-MCC method can be significantly improved by updating the neutral distribution periodically. We compare the computational results with the fixed-neutral PIC-MCC model of the miniature ring-cusp discharge experiment at the University of California, Los Angeles (UCLA). The plasma distribution and potential distribution of the simulation match well with the UCLA experimental data. Compared with the fixed-neutral model, the view factor model increases the simulation time by only 33% while it improves the distribution accuracy of neutrals, plasma density, and electric potential, and reduces the simulation errors of discharge current and discharge power from 19.8% to 9.8%. The accuracy of PIC-MCC simulation has been improved at the expense of slightly increasing the computational time.

关键词： Particle-in-cell methods

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Data-based Formation Control for Underactuated Quadrotor Team via Reinforcement Learning

Data-based Formation Control for Underactuated Quadrotor Tea...

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第三十九届中国控制会议

作者： Hao Liu Wanbing Zhao Frank L.Lewis Zhong-Ping Jiang Hamidreza Modares School of Astronautics Beihang University Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies of Ministry of Education Beihang University the University of Texas at Arlington Research Institute University of Texas at Arlington the Control and Networks Lab Department of Electrical and Computer EngineeringTandon School of EngineeringNew York University the University of Texas at Arlington Research Institute

In this paper, the formation problem of unknown multi-quadrotor systems with underactuation and nonlinearities is addressed. A formation controller including a position controller and an attitude controller is designed. The designed formation controller is based on hierarchical scheme and reinforcement learning method is used to learn the control weights of the formation controller. A simulation of formation of multiple quadrotor systems shows the effectiveness of the proposed controller.

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Attitude Synchronization for Multiple Quadrotors using Reinforcement Learning

Attitude Synchronization for Multiple Quadrotors using Reinf...

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第三十八届中国控制会议

作者： Hao Liu Wanbing Zhao Frank L.Lewis Zhong-Ping Jiang Hamidreza Modares School of Astronautics Beihang University Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies of Ministry of Education Beihang University the University of Texas at Arlington Research Institute University of Texas at Arlington the Control and Networks Lab Department of Electrical and Computer Engineering Tandon School of Engineering New York University the University of Texas at Arlington Research Institute

In this paper, a reinforcement learning based control law is proposed to solve the attitude synchronization problem of the leader-following multi-quadrotor systems. The overall system is composed of a team of quadrotors, modeled with highly nonlinear and coupled dynamics. An optimal control solution is obtained by solving an augmented HamiltonJacobi-Bellman equation. A reinforcement learning approach is used to learn the optimal control law. simulation results are provided to verify the effectiveness of the proposed controller.

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Electric potential barriers in the magnetic nozzle

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Physical Review E 2020年第5期101卷 053208-053208页

作者： Zhiyuan Chen Yibai Wang Haibin Tang Junxue Ren Min Li Zhe Zhang Shuai Cao Jinbin Cao School of Astronautics Beihang University Beijing 100083 China School of Space and Environment Beihang University Beijing 100083 China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies of the Ministry of Education Beihang University Beijing 100083 China Laboratory of Space Environment monitoring and Information Processing Ministry of Industry and Information Technology Beijing 100083 China Shanghai Engineering Centre for Microsatellites Chinese Academy of Sciences Shanghai 201203 China School of Instrumentation and Optoelectronic Engineering Beihang University Beijing 100083 China

Magnetic nozzles are convergent-divergent applied magnetic fields which are commonly used in electric propulsion, manufacturing, and material processing industries. This paper studies the previously overlooked physics in confining the thermalized ions injected from a near-uniform inlet in the magnetic nozzle. Through fully kinetic planar-3V particle-in-cell (PIC) modeling and simulation, an electric potential barrier is found on the periphery of the nozzle throat, which serves to confine the thermalized ions by the electric force. With the initial thermal energy as driving force and insufficient magnetic confinement, the ions overshoot the most divergent magnetic line, which results in the accumulation of positive space charges around the throat. The accumulated charges would create an ion-confining potential barrier with limited extent. Apart from the finite-electron Larmor radius (FELR) effect, two more factors are put forward to account for the limited extent of the potential barrier: the depletion of ion thermal energy and the short-circuiting effect. The influences of inlet temperature ratio of ions to electrons and magnetic inductive strength B0 are quantitively investigated using the PIC code. The results indicate that the potential barrier serves as a medium to transfer the gas dynamic thrust to the magnetic nozzle while providing constrain to the ions, like the solid wall in a de Laval nozzle. In high-B0 regime, the finite-ion Larmor radius (FILR) effect becomes dominant rather than the FELR effect in the plasma confinement of magnetic nozzles.

关键词： Particle acceleration in plasmas Plasma thermodynamics Plasma transport

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High-Resolution Particle Density Measurement for Argon Plasma Plume by Image Reconstruction and Collisional-Radiative Model

SSRN

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SSRN 2022年

作者： Han, Xing Wang, Yimeng Chen, Zhiyuan Wang, Yibai Wu, Jianjun Tang, Haibin Cao, Jinbin School of Space and Environment Beihang University Beijing100083 China School of Astronautics Beihang University Beijing100083 China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies of the Ministry of Education Beihang University Beijing100083 China Aircraft and Propulsion Laboratory Ningbo Institute of Technology Beihang University Ningbo315100 China College of Aerospace Science and Engineering National University of Defense Technology Changsha410073 China Laboratory of Space Environment monitoring and Information Processing Ministry of Industry and Information Technology Beijing100083 China

A measurement method of the high-resolution atom and ion density distributions based on the image reconstruction and collisional-radiative model is presented and could apply to the parameter measurement of the axisymmetric argon plasma plume. The projection integral signals of two-band ion spectral lines and one-band atom spectral line are acquired, and the spatial distribution of the light intensity signals are obtained by the image reconstruction technique. The collisional-radiative model includes the major atomic levels and singly ionized argon levels, taking into account electron-impact excitation and ionization, electron-impact deexcitation, three-body recombination processes to obtain the theoretical signal intensity in the wavelength bands as a function of electron temperature, electron density, and atom density. The plasma parameters are determined by the theoretical signal intensity and spatial light intensity with the three filters, and the common coefficient is calibrated by the known parameters of some positions. The method was applied to the plume region of an applied-field magnetoplasmadynamic thruster to verify the feasibility of this method in comparison with the electrostatic probe, and the plasma parameters with a spatial resolution of 0.81 mm/pixel were obtained finally. © 2022, The Authors. All rights reserved.

关键词： Argon

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