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Moon-tracking Modes for Star trackers

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2010年第1期33卷 171-185页

作者： Enright, John Ryerson Univ Dept Aerosp Engn Toronto ON M5B 2K3 Canada

We examine the effectiveness and robustness of a moon-tracking backup mode for modern star trackers. This approach can be used to calculate a three-axis attitude solution from overexposed images of the moon. In examining this problem, we carefully consider the operational conditions under which this capability would be necessary and tailor our algorithmic approach appropriately. We describe a detailed simulation of the moon imaging process and outline the required image processing steps required to extract useful information from the moon images. The image processing extracts the moon outline and estimates the moon position and orientation using a nonlinear least-squares fit. Under most lighting conditions, our moon-vector estimates have an error of about 0.001 deg, and our sun-vector estimates have an error less than 0.25 deg. The capability of maintaining moderate accuracy attitude tracking in the presence of moon incursions is an important milestone toward a star-tracker-only attitude control system for microsatellites and nanosatellites.

关键词： Attitude Control System Moon Geostationary Satellites Image Processing Attitude tracking Image Formation Earth algorithm Performance track algorithm Metal Oxide Semiconductors

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OBSERVABILITY ANALYSIS FOR TARGET MANEUVER ESTIMATION VIA BEARING-ONLY AND BEARING-RATE-ONLY MEASUREMENTS

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1990年第6期13卷 977-983页

作者： HEPNER, SAR GEERING, HP Swiss Federal Institute of Technology Zurich Switzerland

The implementation of modern guidance laws requires the design of tracking filters that provide information about the target maneuver. Because of the nonlinearity of the tracking problem, the stability of extended Kalman filters in tracking applications involving bearing-(rate-)only observations is highly dependent on the intercept geometry. This is due mainly to the lack of observability in the absence of range measurements. In this paper, the observability of target maneuvers via bearing-(rate-)only measurements is discussed. Intercept scenarios that result in the loss of observability are identified. They play an important role for both the initialization of tracking filters and the design of missile guidance laws based on bearing-(rate-)only measurements.

关键词： Extended Kalman Filter Guidance Laws Missile Guidance track algorithm Heading Angle Inertial Reference System Proportional Navigation Fixed Wing Aircraft Gaussian White Noise Mathematical Models

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Automated Aerial Docking System Using Onboard Vision-Based Deep Learning

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JOURNAL OF AEROSPACE INFORMATION SYSTEMS 2022年第6期19卷 421-436页

作者： Choi, Andrew Jaeyong Park, Jeonghwan Han, Jae-Hung Korea Adv Inst Sci & Technol Dept Aerosp Engn Daejeon 34141 South Korea

This paper proposes an automated aerial docking system for unmanned aerial vehicles. The proposed automated aerial docking system consists of the following two subsystems: 1) docking mechanical system and 2) vision-based deep learning detection/tracking system. A fundamental challenge during the midair docking phase is integration between the leader and follower vehicles with a robust target detection/tracking strategy. This paper presents not only the design of a probe-and-drogue-type aerial docking system, but it also presents the development of an onboard machine learning system for aerial target detection and tracking, which is limited from 0.1 to 3.5 m. The aerial docking system is designed based on a bistable mechanism to increase the robustness of integration and separation between two vehicles. The prototype of the proposed docking mechanism is built by a 3D printer. To employ effective drogue detection in the air, a deep convolutional neural network-based single-stage detector algorithm, YOLOv4-tiny, is applied. Furthermore, to track the moving drogue in the air simultaneously, a point cloud-based tracking algorithm with an RGB-D camera system is developed. The developed deep learning-based detection/tracking system is implemented to be operated in the Arm architecture-based onboard machine learning computer. For performance validation of the proposed automated aerial docking system, a ground test using two robot arms and an indoor flight test using quadcopter drone and an unmanned ground vehicle were conducted.

关键词： Deep Convolutional Neural Network Micro Air Vehicle Unmanned Ground Vehicle Flight Testing Robot Arms track algorithm Quadcopter Machine Learning Aerial Refueling Defense Advanced Research Projects Agencies

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Continuous Monitoring of a Path-Constrained Moving Target by Multiple Unmanned Aerial Vehicles

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2022年第4期45卷 704-713页

作者： Tabasso, Camilla Kielas-Jensen, Calvin' Cichella, Venanzio Manyam, Satyanarayana Casbeer, David W. Weintraub, Isaac Univ Iowa Dept Mech Engn Iowa City IA 52242 USA Infoscitex Corp Dayton OH 45431 USA Air Force Res Lab Control Sci Ctr Excellence Wright Patterson AFB OH 45433 USA Air Force Res Lab Aerosp Syst Directorate Wright Patterson AFB OH 45433 USA

In this work, a continuous monitoring scenario where multiple unmanned aerial vehicles are tasked to monitor a dynamic target moving along a path with unknown speed profile is addressed. Optimal trajectories based on the nominal trajectory of the target are generated offline. If changes in the speed profile of the target are detected, the agents' trajectories can be modified online to ensure that the monitoring requirements are met, while still maintaining intervehicle safety guarantees. The time-coordination algorithm proposed as a solution to this problem is based on a leader-follower structure. The unmanned aerial vehicles are assumed to exchange information over a communication network where limited quality of service, switching topologies, and data package dropouts are considered. Finally, performance bounds and simulation results to prove the efficacy of our method are provided.

关键词： UAV track algorithm Optimal Control Obstacle Avoidance Vehicle Trajectories Heading Angle Motion Planning MATLAB Unmanned Vehicles

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Black-Box Expectation-Maximization algorithm for Estimating Latent States of High-Speed Vehicles

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JOURNAL OF AEROSPACE INFORMATION SYSTEMS 2021年第4期18卷 175-192页

作者： Kim, Yoon-Yeong Kim, Hyemi Lee, WonSung Choi, Han-Lim Moon, Il-Chul Korea Adv Inst Sci & Technol Dept Ind & Syst Engn Daejeon 34141 South Korea SK Telecom Artificial Intelligence Technol Unit Seoul 04539 South Korea Korea Adv Inst Sci & Technol Dept Aerosp Engn Daejeon 34141 South Korea

tracking an object in a noisy environment is difficult, especially when unknown parameters affect the object's behavior. In the case of a high-speed ballistic object, its trajectory is affected by changes in atmospheric conditions as well as various parameters of the object itself. To filter these latent factors of the dynamics model, this paper proposes a black-box expectation-maximization algorithm to estimate the latent parameters and enhance the accuracy of object tracking. The expectation step involves calculating the likelihood of observations through extended Kalman smoothing, which reflects the forward-backward probability combination. The maximization step involves optimizing the unknown parameter, which is the object mass, to maximize the likelihood through Bayesian optimization with Gaussian process regressions. Our simulation experiments show that our algorithm reduces the error of tracking a ballistic object's position given noisy observations with unknown parameters.

关键词： Black Box Bayesian Optimization Cumulative Distribution Function Atmospheric Conditions Unscented Kalman Filter track algorithm Ballistic Coefficient Interacting Multiple Model Earth Rauch Tung Striebel Smoother

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Low-Cost Laser Range-Measurement-Based Terrain-Following Concept and Error Analysis

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2018年第4期41卷 1006-1014页

作者： Livshitz, Arseny Idan, Moshe Technion Israel Inst Technol Fac Aerosp Engn IL-32000 Haifa Israel

The feasibility of a new, low-cost, low-signature, all-weather, terrain-following concept is presented and evaluated. The terrain altitude is assumed to be modeled as a discrete-Markov process with respect to the longitudinal coordinate x. In addition to the two-dimensional (planar) scenario assumption, a point-mass model is chosen to express the aircraft planar dynamics. Consequently, the aircraft motion is represented by a three-degree-of-freedom model. For trajectory-tracking purposes, as an inner loop for the guidance algorithm, the aircraft is also assumed to be equipped with normal acceleration command autopilot, which, for the assumed negligible angles of attack, is equivalent to a flight-path angle rate autopilot. The suggested system that is based on a few simple laser range sensors was shown to be feasible for terrain-following applications. An error analysis of the suggested system was performed and validated against Monte Carlo simulation results. Finally, the proposed analysis model was then used to obtain optimal configuration parameters, in particular optimal pointing angles of the laser range sensor, and its sensitivity to system variations.

关键词： Flight Path Angle Autopilot Guidance System Monte Carlo Simulation track algorithm Bilinear Transform UAV Electromagnetic Pulse Angle of Attack Kalman Filter

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JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2003年第4期17卷 481-487页

作者： Chung, JD Yoo, HS Sejong Univ Dept Mech Engn Seoul 143747 South Korea Soongsil Univ Dept Mech Engn Seoul 156743 South Korea

This paper deals with a similarity solution for the directional solidification of binary peritectic alloys in the presence of shrinkage-induced flow. The present model encompasses the essential ingredients of alloy solidification, such as temperature-solute coupling, macrosegregation, solid-liquid property difference, and finite back diffusion in the primary phase. A new algorithm for simultaneously determining the peritectic reaction and liquidus positions is developed, which proves to be more efficient and stable than the existing schemes. Sample calculations are performed for both hypo- and hyperperitectic compositions of a typical peritectic alloy. The results show that the present analysis is capable of properly resolving the solidification characteristics of peritectic alloys and that it can be used for validating numerical models as a test solution.

关键词： Solidification Newton Raphson Method Magnetic Materials Eutectic Alloys Convection track algorithm Thermal Diffusivity Thermodynamic Equilibrium Superconductor Phase Diagram

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Flame Imaging of Gas-Turbine Relight

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AIAA JOURNAL 2010年第9期48卷 1916-1927页

作者： Read, R. W. Rogerson, J. W. Hochgreb, S. Univ Cambridge Dept Engn Cambridge CB2 1PZ England

High-altitude relight inside a lean-direct-injection gas-turbine combustor is investigated experimentally by highspeed imaging. Realistic operating conditions are simulated in a ground-based test facility, with two conditions being studied: one inside and one outside the combustor ignition loop. The motion of hot gases during the early stages of relight is recorded using a high-speed camera. An algorithm is developed to track the flame movement and breakup, revealing important characteristics of the flame development process, including stabilization timescales, spatial trajectories. and typical velocities of hot gas motion. Although the observed patterns of ignition failure are in broad agreement with results from laboratory-scale studies, other aspects of relight behavior are not reproduced in laboratory experiments employing simplified flow geometries and operating conditions. For example, when the spark discharge occurs, the air velocity below the igniter in a real combustor is much less strongly correlated to ignition outcome than laboratory studies would suggest. Nevertheless, later flame development and stabilization are largely controlled by the cold flowfield, implying that the location of the igniter may, in the first instance, be selected based on the combustor cold flow.

关键词： Gas Turbine Combustor Combustor Design Large Eddy Simulation Fuel Injector Gas Turbine Combustion Chamber Chemiluminescence track algorithm Convection Mass Flow Rate Power Spectral Density

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Standalone Extraction of Tonal Components from Aeroacoustic Signals

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AIAA JOURNAL 2022年第2期60卷 844-859页

作者： Antoni, Jerome Leclere, Quentin Dinsenmeyer, Alice Julliard, Emmanuel Bouley, Simon Picard, Christophe Sijtsma, Pieter Univ Lyon INSA Lyon Lab Vibrat Acoust LVA EA677 F-69621 Villeurbanne France Airbus Operat SAS Acoust Dept F-31300 Toulouse France MicrodB F-69134 Ecully France PSA3 NL-9493 TE De Punt Netherlands

Aeroacoustic signals, as typically returned by recordings of pressure fluctuations generated by rotating machines, often exhibit rich mixtures of tonal and broadband components. The separate analysis of these constituents is important from an engineering point of view, as they relate to different physical mechanisms. This paper is concerned with the extraction of tonal components. The characteristics of aeroacoustic signals can make this task challenging, because tones are numerous, nonharmonically related, and subjected to random modulations. A solution is proposed based on the theory of angle-time cyclostationarity, which seems flexible enough to deal with these constraints. A special effort is made to render the methodology as standalone as possible. This is achieved by automatically setting up the leading parameters with data-driven strategies. The methodology is illustrated on counter-rotating open rotor data that are known to be challenging.

关键词： Short Time Fourier Transform Kalman Filter Blade Passing Frequency Turbulent Boundary Layer Energy Distribution Spectral Analysis Probability Density Functions track algorithm Bias Variance Tradeoff Turbulent Flow

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Aeromaneuvering in the Martian atmosphere: Simulation-based analyses

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JOURNAL OF SPACECRAFT AND ROCKETS 2000年第1期37卷 139-142页

作者： Smith, RS Mease, KD Bayard, DS Farless, DL Univ Calif Santa Barbara Santa Barbara CA 93106 USA Univ Calif Irvine Irvine CA 92697 USA CALTECH Jet Prop Lab Pasadena CA 91109 USA

The development of a MATLAB/SIMULINK-based simulation for Mars precision landings is considered. The modular nature of the simulation makes it readily adaptable to other landing problems and enables straightforward enhancement of the underlying models. It has been used for lift/drag ratio actuation authority and entry condition knowledge error trade-off studies, as well as the development of closed-loop guidance and control algorithms in support of the Mars Surveyor Program 2001 Landing mission. (AIAA)

关键词： Bank Angle Planets Sample Return Missions Yaw Gain Scheduling Spacecraft Modules IMU Thermal Conductivity Pioneer Venus Probes track algorithm

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