检索结果-内蒙古大学图书馆

AIAA SciTech Forum

作者： Kravitz, Eli Ray, Hunter M. Conlon, Nicholas Ahmed, Nisar R. Thomas, Ian Szafir, Danielle Albers Univ Colorado Boulder Smead Aerosp Engn Sci Boulder CO 80309 USA Univ Colorado Boulder Dept Comp Sci Boulder CO 80309 USA Univ North Carolina Chapel Hill Dept Comp Sci Chapel Hill NC USA

ISBN: (数字)9781624107115

ISBN: (纸本)9781624107115

Machine learning models that augment data-intensive human workflows must rely on an understanding of a user's interests and behaviors. By understanding what a user desires, these models can help intuitively prioritize workflow and essential information for decision making, and form the baseline for trusted autonomous systems. This work considers the problem of human interest classification for missile defense surveillance. In this case, users are satellite operators who must prioritize simultaneous processing and characterization of targets across the globe for extended duration while working under strict time and accuracy constraints. Learning human interest in this context is particularly challenging because user interests are generally not static, tracks have a short lifespan, and the user pool is small. Here, we formulated the solution similarly as a binary Bayesian logistic regression problem to classify operator interest in a given candidate track, but with the added complexity of partially observable feature variables and dependencies between these variables. Our approach leverages domain knowledge to instantiate priors on human interest and, using online user interactions with the system, can continuously infer human interest for candidate tracks. We validate our user interest classification algorithm using simulated truth testing across various configurations of expected operator behavior, which overall show that the algorithm can effectively learn relative track interest with minimal training data.

关键词： Satellite Operator Naive Bayes Classifier Missile Defense Autonomous Systems Artificial Intelligence Black Box algorithms ability Monte Carlo Method Computer Vision Geography

来源：评论

学校读者我要写书评

暂无评论

Time Variant Particle Swarm Optimization (TVPSO) for Autonomous Extraterrestrial Rescue and Recovery

Time Variant Particle Swarm Optimization (TVPSO) for Autonom...

引用

AIAA SciTech Forum

作者： Sanders, Kyle Thein, May-Win Univ New Hampshire Durham NH 03824 USA

ISBN: (数字)9781624107115

ISBN: (纸本)9781624107115

Rescue and recovery missions on extraterrestrial sites are an inevitable necessity, especially with increased extraterrestrial exploration. Robotic and crewed missions provide significant challenges from budgetary restrictions and time constraints. Particle Swarm Optimization (PSO) techniques leverage shared swarm knowledge for solution convergence. However, traditional PSO exhibits performance degradation in dynamic scenarios. The authors present Time-Variant Particle Swarm Optimization (TVPSO), which addresses key PSO performance weaknesses for dynamic rescue operations, along with results from numerical simulations in dynamic search environments. The analytical tests confirm TVPSO's marked improvement over that of traditional PSO and indicates its viability for future extraterrestrial missions.

关键词： Particle Swarm Optimization Numerical Simulation Monte Carlo Analysis Astronaut Robots Autonomous Robot Search Algorithm State Space Representation Convergence Analysis algorithms ability

来源：评论

学校读者我要写书评

暂无评论

Geometric Path Following of Underwater Vehicles

Geometric Path Following of Underwater Vehicles

引用

AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Rober, Nicholas Cichella, Venanzio Univ Iowa Dept Mech Engn Iowa City IA 52242 USA

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

This paper addresses the problem of guidance and control of underwater vehicles. The overall control architecture is broken into three different functions: path generation, path following, and vehicle autopilot. The path-generation function creates a 3D path based on mission objectives specified by an operator. A point along the path is tracked by the path-following algorithm, which passes pitch and yaw rate commands to the autopilot. The latter adjusts the vehicle's control surfaces to track the angular rate commands. The introduction of a variable called virtual time allows the target point to be adjusted along the path according to a specified control law. The framework for the path-following algorithm is built upon the Special Orthogonal Group SO(3) with several reference frames relating the vehicle, the virtual target, and the global (inertial) coordinate system. A critical component of the path-following algorithm is the construction of a desired reference frame that specifies the ideal orientation of the vehicle. The desired frame features an adjustable parameter that affects the aggressiveness of the controller, offering the ability to easily adjust its performance. The paper provides guaranteed performance bounds of the path-following algorithm and considers actuation limits on the vehicle's angular rates, as well as limited performance of the on-board autopilot.

关键词： Autopilot Control Surfaces Autonomous Underwater Vehicle Unmanned Aerial Vehicle Computational Fluid Dynamics algorithms ability Motion Planning Track Algorithm Wheeled Robot Euler Angles

来源：评论

学校读者我要写书评

暂无评论

Health Monitoring of Aerospace Structures via Dynamic Strain Measurements: An Experimental Demonstration

Health Monitoring of Aerospace Structures via Dynamic Strain...

引用

AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Martins, B. L. Kosmatka, J. B. Univ Calif San Diego Dept Mech & Aerosp Engn 9500 Gilman DrMail Code 0085 La Jolla CA 92093 USA Univ Calif San Diego Dept Struct Engn 9500 Gilman DrMail Code 0085 La Jolla CA 92093 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

A methodology has been developed to allow for in-situ structural health monitoring of aerospace vehicles during normal (in flight) operation. The method relies on response only power spectral density measurements derived from a network of fiber optic strain gages. The measured strain power spectral densities are compared to previously correlated finite element models using a residual error function. A developed Bayesian objective function minimizes the system imbalance and in turn provides an estimate of the presence, location, type, and severity of damage within a structural system. The developed algorithm was experimentally demonstrated by studying a pair of cuts collocated along the span of a carbon/epoxy composite testbed. The algorithm was shown to successfully identify the presence of damage and well as provide an estimate of the location, type, and severity of the detected damage. In addition to a damage assessment, a product of the health monitoring algorithm is a correlated finite element model of the structure in the damaged state which was shown to globally represent the dynamic behavior of the testbed.

关键词： Power Spectral Density Structural Health Monitoring Finite Element Modeling Structural System Damage Assessment Structural Response Cantilever Beam algorithms ability Material Properties Bending Vibration

来源：评论

学校读者我要写书评

暂无评论

Adaptive determination of the wall-modeled region in WMLES

Adaptive determination of the wall-modeled region in WMLES

引用

AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Kahraman, Ali Berk Larsson, Johan Univ Maryland Dept Mech Engn College Pk MD 20742 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

algorithms for finding the spatial distribution of the thickness of the wall-modeled region (the location where LES data is used as input to a wall-stress model, or where the modeling interface is located) are developed and assessed. The algorithms are physics-based, derived based on known attributes of the turbulence in attached boundary layers. The algorithms are assessed on a range of flows, including flat plate boundary layers, the NASA wall-mounted hump, and different shock/boundary-layer interactions.

关键词： Boundary Layer Interaction Large Eddy Simulation Residual Stress Law of the Wall Friction Coefficient Accelerating Flow Skin Friction Coefficient algorithms ability Free Stream Dirichlet Boundary Condition

来源：评论

学校读者我要写书评

暂无评论

Control Effector Unsaturation Modification to the Cascading Generalized Inverse Control Allocation Algorithm

Control Effector Unsaturation Modification to the Cascading ...

引用

AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Acheson, Michael J. Gregory, Irene Prasad, J. V. R. NASA Langley Res Ctr Dynam Syst & Control Branch Hampton VA 23681 USA NASA Langley Res Ctr Adv Control Theory & Applicat Dynam Syst & Control Branch Hampton VA 23681 USA Georgia Inst Technol Sch Aerosp Engn Atlanta GA 30332 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

Control allocation has sufficiently progressed such that it is used in front-line fighter aircraft such as the F-18 Super Hornet and the F-35 Joint Strike Fighter. Published literature shows the F-35 utilizes nonlinear Dynamic Inversion in conjunction with an effector blender that incorporates the Cascading Generalized Inverse control allocation algorithm. While the Cascading Generalized Inverse algorithm is one of the premier generalized inverse methods, it does suffer from three deficiencies. In particular, it suffers from an inability to achieve some desired outcomes, it intermittently provides non-optimal solutions and generally fails to preserve moment direction near maximal achievable moments. An effector unsaturation method based on a Scalar Difference Quadratic was first introduced and implemented on the iterative Prediction Method control allocation algorithm which was shown to consistently achieve optimal (weighted) control allocation solutions throughout the entire attainable moment set while preserving desired moment direction. In this paper, the shortcomings of the Cascading Generalized Inverse algorithm are addressed by augmenting the baseline algorithm with Scalar Difference Quadratic unsaturation identification and location at each iteration. Numerical case studies demonstrate that the Modified Cascading Generalized Inverse algorithm resolves the aforementioned deficiencies.

关键词： Nonlinear Dynamic Inversion Fighter Aircraft Optimal Control MATLAB Flight Control System High Alpha Research Vehicle Singular Value Decomposition algorithms ability Aircraft Control Quadratic Programming

来源：评论

学校读者我要写书评

暂无评论

Linear Model for Reentry Time Prediction of Spacecraft in Low-Eccentricity, Low Earth Orbits

引用

JOURNAL OF SPACECRAFT AND ROCKETS 2019年第5期56卷 1300-1311页

作者： Bettinger, Robert A. Air Force Inst Technol Dept Aeronaut & Astronaut 2950 Hobson Way Wright Patterson AFB OH 45433 USA

A linear model and associated algorithm for the time prediction of uncontrolled atmospheric reentries is presented for spacecraft in low-eccentricity, near-circular low Earth orbits, specifically at altitudes of 300 km and lower. The primary objective of the present research was to develop a comparatively high-accuracy reentry time prediction algorithm by reducing the complexity of the dynamics model, spacecraft physical model, and the overall computation methodology. As opposed to contemporary higher-fidelity prediction methods, reentry trajectories within the presented model are propagated with reduced three-degree-of-freedom equations of motion. In addition to two-line element data for initial orbit conditions, a solar-cycle-independent pseudo-exponential atmospheric density model with variable inverse scale height is used, coupled with coarse estimates for spacecraft aerodynamic characteristics and shape. The algorithm requires the execution of a series of parametric simulations to determine the reentry time for variations in spacecraft aerodynamic coefficients and drag reference area. When implemented, the linear model yields a mean time prediction accuracy deviation of less than 8 h approximately 5 days before reentry as shown by analysis of the Tiangong-1 reentry, as well as 5 additional example reentry cases from 1979 to 2018. All cases were selected to demonstrate the algorithm's ability to deliver accurate reentry time predictions for spacecraft with varying physical size and mass, and reentering during different periods of solar cycle activity.

关键词： Geostationary Transfer Orbit Spacecrafts Aerodynamic Characteristics Atmospheric Density Prediction algorithms Solar Cycles Three Degrees of Freedom algorithms ability Rossi X Ray Timing Explorer Ballistic Coefficient

来源：评论

学校读者我要写书评

暂无评论

Adaptive Control of Precision Guided Airdrop Systems with Highly Uncertain Dynamics

引用

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2018年第5期41卷 1025-1035页

作者： Cacan, Martin R. Costello, Mark Georgia Inst Technol Woodruff Sch Mech Engn Ctr Adv Machine Mobil Atlanta GA 30322 USA Georgia Inst Technol Auton Guggenheim Sch Aerosp Engn Atlanta GA 30322 USA

The bulk of research in the field of precision guided airdrop systems has focused on improving landing accuracy in the presence of atmospheric winds that can exceed vehicle airspeed. One important challenge of parafoil systems is their highly uncertain flight dynamic behavior and control response, which can result from canopy degradation or an offnominal inflation event. This significantly impacts the ability to reach the target and can often lead to very large miss distances. This work addresses guided airdrop system model uncertainty with a novel combined direct and indirect adaptive control strategy to quickly characterize vehicle dynamics and lateral control sensitivity in flight. Extensive simulation and experimental flight testing indicate that the proposed adaptive algorithm is capable of high-accuracy landing in a large variety of degraded conditions, including unknown nonlinear changes in control sensitivity as well as control reversals. In comparison, current industry standard algorithms experience over an order of magnitude decrease in accuracy when tested under identical scenarios.

关键词： Adaptive Control Algorithm Parafoil Experimental Flight Test Airspeed Control Reversal Adaptive Algorithm Navigation Algorithm GPS Multiple Input Multiple Output algorithms ability

来源：评论

学校读者我要写书评

暂无评论

Instantaneous Quadratic Power-Optimal Attitude Tracking with N Control Moment Gyroscopes

引用

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2017年第3期40卷 701-708页

作者： Lubey, Daniel P. Schaub, Hanspeter Univ Colorado Aerosp Engn Sci Boulder CO 80309 USA

A new globally asymptotically stable tracking control policy that instantaneously optimized a power analogous cost for systems with N control moment gyroscopes (CMGs). This development fills a hole by providing an instantaneous power-optimal infinite-horizon control policy for N CMG systems that is computationally simple to implement for real-time applications. The method developed may be solved via an iterative approach when the system has more than four CMGs, but for systems with four CMGs, an analytical solution was derived. Through a numerical simulation, a comparison between the performance of this power-optimal policy and a more standard minimum norm solution was made. This revealed that both control policies accurately track a moving reference and that the optimal power policy minimizes power usage in the system, with the ability to yield drastic energy savings over the course of an entire maneuver. Because these control policies are optimized instantaneously, there is no guarantee that the power-optimal solution will outperform the minimum norm solution for a given set of gains since they provide convergence via two separate state trajectories.

关键词： Control Moment Gyroscope Attitude Tracking Lyapunov Analysis Lagrange Multipliers Optimal Control Energy Storage Numerical Simulation Reaction Wheels Propellant algorithms ability

来源：评论

学校读者我要写书评

暂无评论

Multiple Horizon Model Predictive Flight Control

引用

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2014年第3期37卷 946-951页

作者： Medagoda, Eran D. B. Gibbens, Peter W. Univ Sydney Sch Aerosp Mech & Mechatron Engn Sydney NSW 2006 Australia

No abstract available.

关键词： Flight Control System Model Predictive Control Airspeed Phugoid Elevator Optimal Control Multiple Input Multiple Output Systems Quadratic Programming Spacecraft Control algorithms ability

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：