Development of a TPS reuse library using COTS tools

In the past, functional test requirements (FTR) or test requirement documents (TRD) and test program sets (TPS) were standalone items developed by individual engineers. In some cases, one engineer would write the FTR/TRD and another would develop the TPS. Commercial ATLAS FTRs are prepared in ARINC 616 and 626 ATLAS. Military TRDs are written in IEEE ATLAS 716 versions. Previous test reuse attempts have not been successful because additional software, like browsers, is required to support these efforts. It was difficult to justify writing new software; for example, browsers to manage the application software. Today, commercial-off-the-shelf (COTS) tools are in place to browse and view information from circuit diagrams to documents to source code. These tools can develop hierarchies to organize the information. These COTS tools are available throughout Boeing on many types of workstations and personal computers on every engineer's desk. This paper discusses how a reusable test library (RTL) is being developed using commercial-off-the-shelf (COTS) tools, such as Mosaic, to address commercial and military test applications. It describes each of the tools and the process to develop TPSs using the reuse library. It defines the metrics and benefits achieved     

利用PHM构建无人机的敏捷保障系统

通过对美国全球鹰无人机系统敏捷保障方案的分析,重点阐明了这一技术和系统设计理念对于我国无人机研制及其飞行保障要求的适用性和实际应用价值,提出了利用故障预测与健康管理、即PHM的手段构建我国无人机敏捷保障系统的一个符合工程实际的技术构架。     

Two-phase visual servoing for capturing tumbling non-cooperative satellites with a space manipulator

In this paper, a visual servoing approach is developed to capture the docking rings of tumbling non-cooperative satellites with a space manipulator. The primary challenge addressed is the potential for the docking ring to leave the monocular camera’s field-of-view as the manipulator approaches the target, due to the ring’s large size. To solve this issue, a two-phase visual servoing scheme combining a monocular camera and a three-line structured light vision system is proposed.In an effort to augment the success rate and safety of capture operations, several constraints are formulated, encompassing manipulator’s kinematics, monocular camera’s field-of-view, obstacle avoidance, structured light’s breakpoints and smooth capture. Subsequently, a nonlinear model predictive controller is proposed to manage these constraints in real-time and regulate the system.System models are established based on image moments and pose for each phase, selecting these features as visual feedback to simplify the formulation of servo constraints and avoid the complex circle-based pose measurement. Furthermore, to ensure unbiased predictions, the model disturbances arising from the imprecise estimation of target motion parameter are observed using an extended Kalman filter, which are then incorporated into the predictive control framework. The simulation results demonstrate the effectiveness of this scheme.     

深刻理解办学指导思想,创造性开展工作

本文从力学指导思想的认识与落实教学改革,师资队伍建设３个方面结合本院实际进行浅议。     

使用LabVIEW和PXI平台开发飞行器结构测试的监测控制系统

<正>西班牙比亚乔航空公司是执行飞行器设计和制造行业中的领导者,我们为该公司开发了应用程序,用于对执行飞行器进行监视和测试。我们将软件程序分为两个部分。一部分在PXI系统上运行,与现     

旋成体表面沟槽减阻试验研究

在旋成体模型表面粘贴铝基沟槽蒙皮,研究沟槽表面对模型阻力的影响。给出基于来流单位雷诺数的沟槽尺寸无量纲公式,用于设计沟槽齿高和齿宽,依据试验风洞的单位雷诺数范围,选定3种尺寸的沟槽进行减阻试验。结果表明,在旋成体表面湍流流动区域顺流向布置沟槽,当沟槽齿高和齿宽的无量纲值h＋、s＋均小于25时,在小迎角下具有减阻作用,当s＋约为15时减阻效果最明显,可减小约3%～4%的阻力。     

SMES benefit analysis using a production cost model for Puget Soundapplication

Superconducting magnetic energy storage (SMES) is an emerging technology that is expected to provide a means of storing electrical energy for use during peak demand periods. Pacific Northwest Laboratory (PNL) has estimated benefits and costs associated with the use of SMES technology and has provided insight into the overall future potential of SMES in the service area of the Bonneville Power Administration (BPA) and on systems that connect and exchange power with BPA     

Robust altitude estimation for over-the-horizon radar using a state-space multipath fading model

In previous work, a matched-field estimate of aircraft altitude from multiple over-the-horizon (OTH) radar dwells was presented. This approach exploits the altitude dependence of direct and surface reflected returns off the aircraft and the relative phase changes of these micro-multipath arrivals across radar dwells. Since this previous approach assumed high dwell-to-dwell predictability, it has been found to be sensitive to mismatch between modeled versus observed micro-multipath phase and amplitude changes from dwell-to-dwell. A generalized matched-field altitude estimate is presented here based on a state-space model that accounts for random ionospheric and target-motion effects that degrade the dwell-to-dwell predictability of target returns. The new formulation results in an efficient, robust recursive maximum likelihood (ML) estimation of aircraft altitude. Simulations suggest that the proposed technique can achieve accuracy within 5,000 ft of the true aircraft altitude, even with relatively high levels of uncertainty in modeling of dwell-to-dwell changes in the target return. A real data result is also presented to illustrate the technique.     

A method for constructing an airfoil using a specified chord velocity diagram

A problem of determining a shape of the airfoil being streamlined by a potential incompressible inviscid flow is solved by the successive approximation method using a specified chord velocity diagram. It is shown that a closed airfoil that possesses a specified chord velocity diagram can be constructed with a sufficient accuracy; if the chord diagram is unsuccessfully specified, the closed airfoil may prove to be not univalent, that is, physically unrealizable.     

The Need for a Wholistic Design Approach when using Gallium Arsenide Technology

The emerging Gallium Arsenide digital integrated circuit technology is rapidly becoming well enough established that designers of signal and data processors are planning its incorporation into advanced computational engines of all types. An examination of the characteristics of present and future generation GaAs integrated circuits indicates that they will emphasize moderate on-chip gate counts and high gate speeds. Complete advantage can be taken of GaAs digital technology only if traditional signal processor architectures are completely recast at the memory layout, logic design, arithmetic implementation, and system architecture levels, and if these issues are considered in combination with system, logic board, and chip layout and packaging constraints in a single integrated approach.     

Aeroelastic system identification using transonic CFD data for a wing/store configuration

This paper is part of a study investigating the prediction of the aeroelastic behaviour of aircraft subjected to non-linear aerodynamic forces. The main objective of the work is the characterization of the dynamic response of aeroelastic models resulting from coupled Computational Fluid Dynamic and Finite Element calculations. Of interest here is the identification of the flight condition at which the response bifurcates to limited or divergent amplitude self-sustained oscillations without carrying out a comprehensive set of full, computationally expensive, time-marching calculations. The model treated in this work is a three-dimensional wing in a transonic flowfield. Short datasets of pre-bifurcation behaviour are analysed to determine the system's stability and degree of non-linearity. It is found that the calculated responses on the run-up to a transonic Limit Cycle Oscillation show little or no evidence of non-linearity. The non-linearity appears abruptly at the bifurcation flight condition. The variation of the local Mach number over the wing's surface in the steady-state case is used to demonstrate that the non-linearity is due to a shock wave that can move along the surface. At Mach numbers where this is not possible the system behaves in a linear manner and its stability can be analysed using linear methods.     

Modeling and control for cooperative transport of a slung fluid container using quadrotors

In this paper, dynamic modeling and control problem for transfer of a sloshing liquid container suspended through rigid massless links from a team of quadrotors are investigated. By the proposed solution, pose of the slung container and fluid sloshing modes are stabilized appropriately. Dynamics of the container-liquid-quadrotors system is modeled by Euler-Lagrange method. Fluid slosh dynamics is included using multi-mass-spring model. According to derived model, a proper control law is designed for a system with three or more quadrotors. Implementing the proposed control law, quadrotors can control pose of the container, directions of the links and liquid sloshing modes simultaneously. Stability of closed loop system of tracking errors and sloshing modes are demonstrated using a theory of singularly perturbed systems and Lyapunov stability theorem. Also, the capability of the proposed feedback control laws in solving a formerly organized transport problem of a liquid filled container has been demonstrated in simulations. Moreover, priority of the proposed control scheme to an existing slung load controller in the literature is demonstrated.     

Methodology of using artificial neural networks for imitating the loading of a single-rotor helicopter

A methodology of creating a loading imitation model of a single-rotor helicopter with artificial neural network algorithms is considered. Stages of creation, the structure, and an algorithm of searching for an optimal neural networks configuration of loading imitation model are presented.     

Achieving a hands-free computer interface using voice recognitionand speech synthesis [for Windows-based ATE]

Software designers at Hill Air Force Base have developed a voice recognition and speech synthesis system (Voice Control) for use with the F-16 Analog Test Station Sustainment (FATSS) project. The Voice Control system is reliable, speaker independent, and has a total added hardware price tag of under $50.00 per station. In contrast to traditional voice recognition systems, operator training is not required. OO-ALC has developed a general-purpose internal interface (Voice Control) to the Speech Recognition and Text-To-Speech engines provided by Microsoft. Voice Control can be accessed by any 32-bit Windows software, which has windows messaging capability. This is available to standard programming languages such as LabWindows CVI, Borland or Microsoft C/C++, Visual Basic, or even commercial packages such as Lotus Notes and Microsoft Word. Through Voice Control, the computer uses both video and voice prompts to request input from the operator. The operator is allowed to enter data and to control the software flow by voice command or from the keyboard or mouse. The Voice Control system allows for dynamic specification of a grammar set, or legal set of commands. The use of a reduced grammar set greatly increases recognition accuracy. The computer voice enables the operator to focus his attention away from the computer screen, which is required for activities such as probing a circuit card and taking readings. When the operator takes readings, the computer, to insure reliable entry, echoes his voice entries. With electronic tuning, speech synthesis allows the operator to hear the resulting reading, enabling him to focus on the circuit card instead of constantly turning his head to see the computer screen. This paper describes the capability and functionality of the Voice Control system     

High-resolution simulation for rotorcraft aerodynamics in hovering and vertical descending flight using a hybrid method

A high-resolution simulation tool for rotorcraft aerodynamics is developed by coupling CFD with a Vorticity Transport Model (VTM). An Eulerian-based CFD module is used to model the blade near body flowfield, and a Lagrangian-based VTM module is employed for vortex tracking in the far wake. The coupling procedure is implemented by transmitting vortex sources to the VTM module and feeding boundary conditions back to the CFD module. The presented CFD/VTM hybrid solver is firstly validated by hover cases of three different rotor configurations. Simulation results, including the blade surface pressure distribution, rotor downwash, and hover figure of merit, exhibit favorable correlations with available experimental data. Then, a rotor operated in vertical descending flight with a fixed collective pitch is investigated. It is shown that the CFD/VTM coupling method is suitable for rotor wake simulation. Wake instabilities (far wake breakdown in hover and toroidal wake pattern in the vortex ring state) are successfully demonstrated with a moderate computational cost.     

Online condition diagnosis for a two-stage gearbox machinery of an aerospace utilization system using an ensemble multi-fault features indexing approach

China manned space station is designed to operate for over ten years. Long-term and sustainable research on space science and technology will be conducted during its operation. The application payloads must meet the ‘‘long life and high reliability" mission requirement. Gearbox machinery is one of the essential devices in an aerospace utilization system, failure of which may lead to downtime loss even during some disastrous catastrophes. A fault diagnosis of gearbox has attracted attentions for its significance in preventing catastrophic accidents and guaranteeing sufficient maintenance. A novel fault diagnosis method based on the Ensemble Multi-Fault Features Indexing(EMFFI) approach is proposed for the condition monitoring of gearboxes. Different from traditional methods of signal analysis in the one-dimensional space, this study employs a supervised learning method to determine the faults of a gearbox in a two-dimensional space using the classification model established by training the features extracted automatically from diagnostic vibration signals captured. The proposed method mainly includes the following steps. First, the vibration signals are transformed into a bi-spectrum contour map utilizing bi-spectrum technology,which provides a basis for the following image-based feature extraction. Then, Speeded-Up Robustness Feature(SURF) is applied to automatically extract the image feature points of the bi-spectrum contour map using a multi-fault features indexing theory, and the feature dimension is reduced by Linear Discriminant Analysis(LDA). Finally, Random Forest(RF) is introduced to identify the fault types of the gearbox. The test results verify that the proposed method based on the multi-fault features indexing approach achieves the target of high diagnostic accuracy and can serve as a highly effective technique to discover faults in a gearbox machinery such as a two-stage one.     

A new iterative algorithm for geolocating a known altitude target using TDOA and FDOA measurements in the presence of satellite location uncertainty

This paper considers the problem of geolocating a target on the Earth surface whose altitude is known previously using the target signal time difference of arrival(TDOA) and frequency difference of arrival(FDOA) measurements obtained at satellites. The number of satellites available for the geolocation task is more than sufficient and their locations are subject to random errors. This paper derives the constrained Crame′r-Rao lower bound(CCRLB) of the target position, and on the basis of the CCRLB analysis, an approximately efficient constrained maximum likelihood estimator(CMLE) for geolocating the target is established. A new iterative algorithm for solving the CMLE is then proposed, where the updated target position estimate is shown to be the globally optimal solution to a generalized trust region sub-problem(GTRS) which can be found via a simple bisection search. First-order mean square error(MSE) analysis is conducted to quantify the performance degradation when the known target altitude is assumed to be precise but indeed has an unknown but deterministic error. Computer simulations are used to compare the performance of the proposed iterative geolocation technique with those of two benchmark algorithms. They verify the approximate efficiency of the proposed algorithm and the validity of the MSE analysis.