检索结果-内蒙古大学图书馆

arXiv 2022年

作者： Beckenbach, Lukas Osinenko, Pavel Streif, Stefan The Laboratory for Automatic Control and System Dynamics Technische Universität Chemnitz Chemnitz09107 Germany The Digital Engineering Center Skolkovo Institute of Science and Technology Moscow121205 Russia

Reinforcement learning is commonly associated with training of reward-maximizing (or cost-minimizing) agents, in other words, controllers. It can be applied in model-free or model-based fashion, using a priori or online collected system data to train involved parametric architectures. In general, online reinforcement learning does not guarantee closed loop stability unless special measures are taken, for instance, through learning constraints or tailored training rules. Particularly promising are hybrids of reinforcement learning with "classical" control approaches. In this work, we suggest a method to guarantee practical stability of the system-controller closed loop in a purely online learning setting, i. e., without offline training. Moreover, we assume only partial knowledge of the system model. To achieve the claimed results, we employ techniques of classical adaptive control. The implementation of the overall control scheme is provided explicitly in a digital, sampled setting. That is, the controller receives the state of the system and computes the control action at discrete, specifically, equidistant moments in time. The method is tested in adaptive traction control and cruise control where it proved to significantly reduce the *** Codes 93D15 © 2022, CC BY-NC-ND.

关键词： Reinforcement learning

来源：评论

学校读者我要写书评

暂无评论

Rotating machinery fault diagnosis based on convolutional neural network and infrared thermal imaging

引用

Chinese Journal of Aeronautics 2020年第2期33卷 427-438页

作者： Yongbo LI Xiaoqiang DU Fangyi WAN Xianzhi WANG Huangchao YU MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical UniversityXi’an 710072China School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an 710072China Institute of Unmanned System National University of Defense TechnologyChangsha 410073China

Rotating machinery is widely applied in industrial *** diagnosis of rotating machinery is vital in manufacturing system,which can prevent catastrophic failure and reduce financial ***,Deep Learning(DL)-based fault diagnosis method becomes a hot *** Neural Network(CNN)is an effective DL method to extract the features of raw data *** paper develops a fault diagnosis method using CNN for InfRared Thermal(IRT)***,IRT technique is utilized to capture the IRT images of rotating ***,the CNN is applied to extract fault features from the IRT *** the end,the obtained features are fed into the Softmax Regression(SR)classifier for fault pattern *** effectiveness of the proposed method is validated using two different experimental *** show that the proposed method has a superior performance in identification various faults on rotor and bearings comparing with other deep learning models and traditional vibration-based method.

关键词： Convolutional neural network Feature extraction Infrared thermography(IRT) Intelligent fault diagnosis Rotating machinery

来源：评论

学校读者我要写书评

暂无评论

Observability Analysis for Spacecraft Attitude Determination using a Single Temperature Sensor*

Observability Analysis for Spacecraft Attitude Determination...

引用

European control Conference (ECC)

作者： Tobias Posielek Johann Reger Institute of System Dynamics and Control German Aerospace Center (DLR) Wessling Germany Control Engineering Group Technische Universität Ilmenau Ilmenau Germany

We consider the problem of spacecraft attitude determination using temperature data. Common algorithms fuse multiple temperature measurements to reconstruct the attitude. However, a single sensor already contains a lot of information due to the temperature dynamics inherent to the nonlinear structure. In this work a rigorous observability analysis is carried out to determine the configurations in which the combination of a single temperature sensor with angular velocity measurements is sufficient for estimating the entire attitude. We evaluate the observability properties of the different configurations and give recommendations for the best configurations.

关键词： Temperature measurement Temperature sensors Space vehicles Manifolds Radiation effects Temperature distribution Position measurement

来源：评论

学校读者我要写书评

暂无评论

Robust Path-following control with Anti-Windup for HALE Aircraft

Robust Path-following Control with Anti-Windup for HALE Airc...

引用

Mediterranean Conference on control and Automation (MED)

作者： Christian Weiser Daniel Ossmann Harald Pfifer German Aerospace Center (DLR) Institute of System Dynamics &amp Control We&#x00DF ling Germany Department of Mechanical Automotive &amp Aerospace Engineering Munich University of Applied Sciences HM Munich Germany Chair of Flight Mechanics &amp Control TU Dresden Dresden Germany

ISBN: (数字)9781665406734

ISBN: (纸本)9781665406741

In this paper, a robust path-tracking controller for a High Altitude Long Endurance (HALE) aircraft is presented. The main control paradigm for operating a HALE aircraft consists of a basic path following control, i.e. tracking a reference flight path and airspeed while dealing with very limited thrust. The priority lies in keeping airspeed inside the small flight envelope of HALE aircraft even during saturated thrust. For the basic path following objective, a mixed sensitivity approach is proposed which can easily deal with decoupled tracking and robustness requirements. To deal with saturated control inputs, an anti-windup scheme is incorporated in the control design. A novel observer-based mixed sensitivity design is used which allows directly using classical anti-windup methods based on back-calculation. The control design is verified in nonlinear simulation and compared to a classical total energy control based controller.

关键词： State feedback Sensitivity systematics control design Windup Atmospheric modeling Aircraft

来源：评论

学校读者我要写书评

暂无评论

Enhanced carbonate weathering and CO2 release in a typical karst watershed (Southwest China): Evidence from hydrochemical and multi-isotopic data

引用

Science of the Total Environment 2024年 957卷 177372页

作者： Liu, Lei Lan, Jiacheng Ren, Kun Huang, Mingzhi Mao, Ruitao Zhang, Xianwen Yue, Kunqian School of Karst Science / State Engineering Technology Institute for Karst Desertiffcation control Guizhou Normal University Guiyang550001 China Institute of Karst Geology Chinese Academy of Geological Sciences Key Laboratory of Karst Dynamics Ministry of Natural Resources & Guangxi Guilin541004 China International Research Centre on Karst under the Auspices of UNESCO National Center for International Research on Karst Dynamic System and Global Change Guilin541004 China Pingguo Guangxi Karst Ecosystem National Observation and Research Station Pingguo531406 China

Carbon sinks formed by carbonate weathering are a major component of the carbon sink deficit and play a significant role in the carbon cycle. However, exogenous acids (HNO3 and H2SO4) are also involved in carbonate weathering, complicating the overestimation of the formation of carbon sinks and fluxes. In this study, we analyzed the Hongjiadu karst underground river basin in Guizhou using isotopes (δ13C-DIC, δ34S-SO4, δ18O-SO4, δ18O-H2O, and δ2H-H2O) and hydrochemical methods to investigate carbon cycling characteristics and its influencing factors, and quantitatively evaluate the effects of HNO3 + H2SO4 on CO2 sink fluxes in the basin. The following results were obtained: (1) The nitrate in the watershed mainly comes from fertilizers, and the sulfate mainly comes from local coal seams. (2) The relationship between isotopes (δ13C-DIC, δ34S-SO4, δ18O-SO4, δ18O-H2O, and δ2H-H2O) and hydrochemicals (Ca2+, Mg2+, NO3–, HCO3–, and SO42–) indicates that H2CO3, HNO3, and H2SO4 are involved in carbonate rock dissolution. Most of the samples in the watershed, particularly the acid mine drainage water, were affected by acid rain and sulfide oxidation, resulting in increased δ13C-DIC values. Another portion of the springs was affected by soil CO2, resulting in decreased δ13C-DIC values. (3) Quantitative calculations showed that exogenous acids enhanced the weathering rate of carbonate rocks in groundwater by 67.24 % (dry season) and 76.31 % (wet season) while decreasing the carbon sink flux in groundwater by 55.31 % (dry season) and 66.64 % (wet season). Rainfall enhances the weathering of carbonate rocks. In the process, CO2 is released, increasing the carbon source. Our study highlights the influence of anthropogenic, natural, and hydrological changes on karst carbon sinks in mixed-pollution karst basins. This information is important for future studies on the carbonate weathering processes in karst regions. © 2024 Elsevier B.V.

关键词： Groundwater pollution

来源：评论

学校读者我要写书评

暂无评论

control design with guaranteed transient performance: An approach with polyhedral target tubes

arXiv

引用

arXiv 2021年

作者： Esterhuizen, Willem Wang, Qing-Guo Technische Universität Chemnitz Automatic Control & System Dynamics Laboratory Germany Institute for Intelligent Systems Faculty of Engineering and the Built Environment University of Johannesburg South Africa

In this paper a novel approach is presented for control design with guaranteed transient performance for multiple-input multiple-output discrete-time linear polytopic difference inclusions. We establish a theorem that gives necessary and sufficient conditions for the state to evolve from one polyhedral subset of the state-space to another. Then we present an algorithm which constructs a time-varying output feedback law which guarantees that the state evolves within a time-varying polyhedral target-tube specifying the system’s desired transient performance. We present generalisations involving constraints on the control, and a bounded additive disturbance term. Our formulation is very general and includes reference tracking with any desired transient behaviour in the face of disturbances, as specified, for example, by the most popular step response specifications. The approach is demonstrated by an example involving the control of water levels in two coupled *** Codes 93C35, 93C05, 93B52 © 2021, CC BY-NC-ND.

关键词： Transient analysis

来源：评论

学校读者我要写书评

暂无评论

Multi-constraint UAV Fast Path Planning Based on Improved A∗ Algorithm 2

Multi-constraint UAV Fast Path Planning Based on Improved A...

引用

2020 2nd International Conference on Computer Modeling, Simulation and Algorithm, CMSA 2020

作者： Kong, Xiaodi Pan, Bin Cherkashin, Evgeny Zhang, Xiaoyang Liu, Linke Hou, Jian School of Computer and Communication Engineering Liaoning ShiHua University Fushun China School of Science Liaoning ShiHua University Fushun China Matrosov Institute for System Dynamics Control Theoiry of SB RAS Novosibirsk Russia

Path planning is an important part of UAV intelligent control technology. For the current UAV path planning, the A∗ algorithm has a large memory overhead during the planning process, and the search speed is slow. It cannot meet the path planning in a complex three-dimensional environment. The immediacy requirement and considering the constraints are less, this paper made the following improvements to the A∗ algorithm. The first, combining an anytime repair search framework with a weighted A∗ algorithm, it is possible to quickly find a feasible path during the search process. The second, aiming at the defect of relying on low heuristic function weights in the algorithm, a double ranking criterion is proposed to improve the efficiency of the algorithm approaching the optimal path in the iterative process. And third, to reduce the number of node expansions in the planning process, increase list storage constraints have been improved. Finally, the results of simulation experiments show that the improved algorithm proposed in this paper can quickly generate feasible paths, and can continuously optimize the approach to the optimal path within a specified time, which is far superior to the traditional A∗ algorithm in terms of planning efficiency and immediacy. © Published under licence by IOP Publishing Ltd.

关键词： Motion planning

来源：评论

学校读者我要写书评

暂无评论

A Novel Attitude Representation in View of Spacecraft Attitude Reconstruction using Temperature Data ⁎

引用

IFAC-PapersOnLine 2021年第14期54卷 500-505页

作者： Tobias Posielek Johann Reger Institute of System Dynamics and Control German Aerospace Center (DLR) Münchner Str. 20 D-82234 Weßling Germany Control Engineering Group Technische Universität Ilmenau P.O. Box 10 05 65 D-98684 Ilmenau Germany

There are various different attitude representations that describe the orientation of a rigid body in space and allow the transformation between different coordinate systems. Among others, they differ in number of variables, uniqueness of the representation and their continuity. However, in spite of some of them being based on angles, none of them constitutes a simple representation of an angle between two arbitrary vectors. We tackle this issue by proposing a novel attitude representation that directly incorporates the desired angle. The usefulness of this representation is demonstrated in the attitude reconstruction from temperature data, which then leads to an order reduction of a non-linear system.

关键词： Modeling Identification of Nonlinear systems Aerospace control systems control of Nonlinear systems

来源：评论

学校读者我要写书评

暂无评论

On inf-convolution-based robust practical stabilization under computational uncertainty

arXiv

引用

arXiv 2021年

作者： Schmidt, Patrick Osinenko, Pavel Streif, Stefan Technische Universität Chemnitz Automatic Control and System Dynamics Lab Chemnitz09126 Germany Computational and Data Science and Engineering Center Skolkovo Institute of Science and Technology Moscow143026 Russia

This work is concerned with practical stabilization of nonlinear systems by means of inf-convolution-based sample-and-hold control. It is a fairly general stabilization technique based on a generic non-smooth control Lyapunov function (CLF) and robust to actuator uncertainty, measurement noise, etc. The stabilization technique itself involves computation of descent directions of the CLF. It turns out that non-exact realization of this computation leads not just to a quantitative, but also qualitative obstruction in the sense that the result of the computation might fail to be a descent direction altogether and there is also no straightforward way to relate it to a descent direction. Disturbance, primarily measurement noise, complicate the described issue even more. This work suggests a modified inf-convolution-based control that is robust w. r. t. system and measurement noise, as well as computational uncertainty. The assumptions on the CLF are mild, as, e. g., any piece-wise smooth function, which often results from a numerical LF/CLF construction, satisfies them. A computational study with a three-wheel robot with dynamical steering and throttle under various tolerances w. r. t. computational uncertainty demonstrates the relevance of the addressed issue and the necessity of modifying the used stabilization technique. Similar analyses may be extended to other methods which involve optimization, such as Dini aiming or steepest descent. © 2021, CC BY-NC-ND.

关键词： Nonlinear systems

来源：评论

学校读者我要写书评

暂无评论

Soft-Landing dynamics of a Type of Four-Legged Space Lander

SSRN

引用

SSRN 2024年

作者： Shi, Tengfei Shi, Tengfei Yang, Yinping Zhang, Zhijuan Liu, Cuicui Liu, Caishan Ma, Daolin Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace Engineering Southwest Jiaotong University Chengdu610031 China State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing100871 China Institute of Dynamics and Control College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology Beijing100871 China China Academy of Space Technology Beijing100094 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai200240 China Key Laboratory of Marine Intelligent Equipment and System Ministry of Education Shanghai200240 China

Analyzing the landing dynamics response is essential for enhancing the success rate of surface explorations on Mars, the moon, or asteroids. This paper develops a comprehensive dynamics model for a space lander equipped with four sets of buffer legs, each consisting of a primary strut, two secondary struts, and a footpad, during its soft landing process. The degrees of freedom of the main body and the footpads are defined as generalized coordinates to describe the motion of the space lander. The compression force of the buffer struts is obtained by interpolating real experimental data, and the contact force between the footpad and the ground is calculated using Archimedes law for granular media. Then, the dynamical model for the lander in terms of minimal degrees of freedom can be constructed by applying the Lagrange equations of the second kind. The proposed dynamics model is validated by the experiments of a single-legged lander vertical touchdown and a four-legged lander free touchdown. Moreover, histories of buffer force, acceleration of the main body, and other key physical quantities are computed to investigate the landing process. This highly efficient and accurate dynamics model provides a method to perform extensive simulations to design and optimize a soft landing process. © 2024, The Authors. All rights reserved.

关键词： Landing

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：