2007 IEEE Aerospace Conference最新文献

{"title":"Bearing Line Tracking and Bearing-Only Target Motion Analysis","authors":"F. Bonneton, C. Jauffret","doi":"10.1109/AERO.2007.353037","DOIUrl":"https://doi.org/10.1109/AERO.2007.353037","url":null,"abstract":"The framework of this paper is a passive sonar system, more precisely at the core of bearing estimation and bearings-only target motion analysis (BO-TMA). A cosine of relative bearing estimation and bearings v.s. time image is first obtained by a conventional frequency-domain beam-former [D.H Johnson et al, 1993]. Computing the first two moments of each line of this image, we evaluate the likelihood of the cosine of relative bearing of the target. Then, the cosine of relative bearing and its derivative are considered as the two components of a state vector of a linear dynamic system. This state vector is then estimated (or extracted) by a classical algorithm of the hidden Markov model (HMM) arsenal, whose parameters are adjusted according to the statistical assumptions. Unlike, we consider the presence of one sole target, but the beginning and the end of the line are unknown and must be estimated too. The extracted track is used as measurements set of the BO-TMA. Finally, the confrontation of the TMA results allow us to evaluate the performance of the triplet (beam-former, bearing extraction, BO-TMA).","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"12 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87342369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Self-Supervised Classification for Planetary Rover Terrain Sensing","authors":"Christopher A. Brooks, K. Iagnemma","doi":"10.1109/AERO.2007.352693","DOIUrl":"https://doi.org/10.1109/AERO.2007.352693","url":null,"abstract":"Autonomous mobility in rough terrain is key to enabling increased science data return from planetary rover missions. Current terrain sensing and path planning approaches can be used to avoid geometric hazards, such as rocks and steep slopes, but are unable to remotely identify and avoid non-geometric hazards, such as loose sand in which a rover may become entrenched. This paper proposes a self-supervised classification approach to learning the visual appearance of terrain classes which relies on vibration-based sensing of wheel-terrain interaction to identify these terrain classes. Experimental results from a four-wheeled rover in Mars analog terrain demonstrate the potential for this approach.","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"42 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87710288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automated Classification of Visible and Near-Infrared Spectra Using Self-Organizing Maps","authors":"T. Roush, R. Hogan","doi":"10.1109/AERO.2007.352701","DOIUrl":"https://doi.org/10.1109/AERO.2007.352701","url":null,"abstract":"Existing and planned space missions to planetary and satellite surfaces produce increasing volumes of spectral data. Understanding the scientific content in this large data volume is a daunting task. Various statistical approaches are available to assess such data sets. We apply an automated classification scheme based on Kohonen Self-Organizing maps (SOM) developed originally for the thermal infrared (TIR) and extended here to the visible and near-infrared (VNIR). Available data from spectral libraries are used to train and test the classification in the VNIR. The library spectra are labeled in a hierarchical scheme with class, sub-class, and mineral group names. After training, the test spectra are presented to the SOM output layer and assigned membership to the appropriate cluster. These assignments are then evaluated to assess the robustness, scientific meaning and accuracy of the derived SOM classes as they relate to the spectral labels. We investigate the influence of particle size on our results by training and classifying three particle size separates. We find the SOM results are robust based upon the number of clusters determined from ten independent training/testing efforts. We find the SOM results are most scientifically meaningful for the grossest differences between materials, although some individual groups retain high accuracy even when the overall accuracy of the SOM is low.","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"57 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85987721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Routing In Deep-Space Satellite Networks With Lossy Links","authors":"V. Maramreddy, O. Amadasun, V. Sarangan, J. Thomas","doi":"10.1109/AERO.2007.352898","DOIUrl":"https://doi.org/10.1109/AERO.2007.352898","url":null,"abstract":"This paper proposes routing schemes to forward packets in deep space networks with lossy links. The proposed schemes build on the framework proposed by Clare et. al and are sensitive to the energy consumed and link error rates along a satellite link. In the presence of lossy links, it is a common practice in terrestrial networks to retransmit packets lost due to errors. However, it is not clear if such a strategy will be suitable for deep-space networks, since the long propagation delays associated with the satellite links could hinder the data transfer rate. Further, packet re-transmissions also increase the energy load on a satellite, thereby straining their limited energy reserves. This leads to the following question: \"Is it worthy to retransmit packets lost due to errors in deep space networks to ensure 100% data reliability or is it sufficient to forward the packets along the path with maximum reliability without any re-transmissions?\" In an attempt to answer the above question, we propose two routing schemes and compare their performance through simulations against a vanilla routing scheme in terms of energy consumption, reliability, and throughput.","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"16 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85993725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aperture Efficiency of Amplitude Weighting Distributions for Array Antennas","authors":"G. Hopkins, J. Ratner, A. Traille, V. Tripp","doi":"10.1109/AERO.2007.352856","DOIUrl":"https://doi.org/10.1109/AERO.2007.352856","url":null,"abstract":"Array antennas offer a wide range of opportunities in the variation of their directivity patterns through amplitude and phase control. Peak sidelobe levels may be reduced via amplitude control or weighting across the array aperture. Several authors have made significant contributions in detailing processes for synthesizing these aperture amplitude distributions for the purpose of sidelobe level control. One of the basic trade-offs when implementing amplitude weighting functions is that a trade between low sidelobe levels and a loss in main beam directivity always results. Some of the commercially available pattern calculation programs that can implement sidelobe level control do not provide calculations of the aperture efficiencies given different amplitude weightings. Calculation of the aperture efficiency can be somewhat confusing, particularly with regards to the difference between tapering via attenuation versus redistribution. The purpose of this paper is to define these terms, to provide a review of the proper normalization technique that is important in obtaining accurate aperture efficiency estimation. Descriptions of the amplitude tapers and their utility will be presented. A design example will be presented which will compare theoretical efficiencies with those obtained via finite element method simulation.","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"48 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90940595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Technology Demonstration of Ka-band Digitally-Beam formed Radar for Ice Topography Mapping","authors":"G. Sadowy, B. Heavey, D. Moller, E. Rignot, M. Zawadzki, S. Rengarajan","doi":"10.1109/AERO.2007.353074","DOIUrl":"https://doi.org/10.1109/AERO.2007.353074","url":null,"abstract":"GLISTIN (Glacier and Land Ice Surface Topography Interferometer) is a spaceborne interferometric synthetic aperture radar for topographic mapping of ice sheets and glaciers. GLISTIN will collect ice topography measurements over a wide swath with sub-seasonal repeat intervals using a Ka-Band digitally-beamformed antenna. This paper will give an overview of the system design and key technology demonstrations including a Im x Im digitally-beamformed Ka-band waveguide slot antenna with integrated digital receivers. We will also detail the experimental scenario that we will use to demonstrate both the beamforming and interferometric performance of this system.","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"129 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86385697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clutter Suppression for Airborne Radar with Cylindrical Array Antennas","authors":"W. Xie, Yongliang Wang","doi":"10.1109/AERO.2007.353070","DOIUrl":"https://doi.org/10.1109/AERO.2007.353070","url":null,"abstract":"Cylindrical array antennas have three merits such as all-orientation space scanning, flexible search and track mode and good beam bearing relative to common planar array antennas. In this paper, firstly the differences between cylindrical array and uniform planar array are discussed in terms of eigenvalue distribution of the clutter covariance matrix and clutter distribution at range, and the conclusion of space-time clutter spectrum nonhomogeneity at range for airborne radar with cylindrical array antennas is gained. Secondly three novel clutter suppression methods are proposed to address the problem of clutter spectrum nonhomogeneity at range. Finally, simulation results verify the correctness of the proposed methods.","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"227 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81667055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Precision Deployable Aperture System Facility","authors":"T. Cwik, G. Agnes, A. Moussessian, C. Norton, F. Zhao","doi":"10.1109/AERO.2007.352862","DOIUrl":"https://doi.org/10.1109/AERO.2007.352862","url":null,"abstract":"Precision deployment is an enabling technology for future NASA large aperture missions. Possible concept missions include optical, infrared, sub-millimeter, or microwave apertures too large to fit unfolded in a launch shroud. Dimensional stability is the overriding structural design driver for these large deployable apertures. The stability is driven by constraints derived from the system's mass and structural stability and to thermal and dynamical loads. As the aperture size increases, and the systems mass density is correspondingly decreased, the ability to test the performance of these apertures in a 1-g environment requires both a unique facility and special testing methodologies. This talk will describe a facility under development that includes an enclosure with extreme environmental control, a metrology systems for measuring deployment precision and aspects of an integrated modeling system that will be validated in the facility. Though built to the demanding specifications of deployed optical systems, this talk will focus on components of the facility specific to space-based microwave and millimeter wave antenna systems. The first component of the facility is an enclosure with 10 m times 5 m times 3 m (L times W times H) usable volume that is controlled under ambient temperature to thermal stability of <0.01 Cdeg/Hr, acoustic control of <35 dBA and seismic control of <10 mugs. The enclosure includes a gravity offload system and allows development of single and multi-petal test articles. Instrumentation in the facility includes three-dimensional videogrammetry system capable of absolute measurement accuracy less than 1 millimeter, and a laser vibrometer system for modal testing. The second component of the facility is the development of an optical metrology system for aligning and monitoring large, deployable structures and telescopes to a fraction of a wavelength. A six beam 'optical hexapod' metrology gauge is being built that will measure to 1 micron absolute accuracy with 1 nanometer relative accuracy over a 10 m range. The final component of the facility is comprised of system architecture and modeling components using integrated modeling tools for predictive simulations of aperture systems under orbital loads. These models are being compared to controlled experiments completed in the facility.","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"7 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81842043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2-Dimensional Integrated VCSEL and PiN Photodetector Arrays for a Bidirectional Optical Links","authors":"K. Choquette, A. Giannopoulos, A. Kasten, C. Long, Cheng Chen","doi":"10.1109/AERO.2007.353012","DOIUrl":"https://doi.org/10.1109/AERO.2007.353012","url":null,"abstract":"We have designed, fabricated, and characterized separate and monolithically integrated 2-dimentional vertical cavity surface emitting laser (VCSEL) and photodetector arrays for optical board-to-board communications. The arrays of VCSELs, detectors, and integrated arrays have been fabricated on a hexagonal grid so as to maximize the number of devices that can be coupled to a circular waveguide. The integrated laser/detector arrays are in intermeshed hexagonal grids of the same period but are offset one half of a period. This results in die that have mirror symmetry after a rotation of 60 degrees. The photodetector epilayers are grown epitaxially on top of a conventional VCSEL structure. A novel fabrication process is employed which enables etching down to carefully expose the top laser facet. Device characteristics are observed to be uniform across the entire array. This in addition to the mirror symmetry of the die allow for the usage of these arrays as optical transceivers.","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"49 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84842555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Field Testing of Lunar Access and Navigation Device (LAND)","authors":"C. Liebe, J. Alexander, M. Aung, H. Goldberg, A. Johnson, R. Lam, E. Maize, P. Meras, J. Montgomery, Pilar Tejada Palacios, G. Spiers, M. Wilson","doi":"10.1109/AERO.2007.353018","DOIUrl":"https://doi.org/10.1109/AERO.2007.353018","url":null,"abstract":"A laser radar system has been constructed. It is based on a commercial PC with digitizer, pulse delay instrument, National Instruments IO card and an optical head from a previous laser radar program. The laser radar was mounted on a gyro stabilized gimbal on the nose of a helicopter and flown in the Mojave Desert in September 2006. The collected data will be used to test algorithms for future precision lunar landers, which may be utilizing a laser radar as the primary landing sensor. This paper will describe the laser radar and PC based acquisition system used for the data collection, and provide an overview of the supporting test sensors and architecture. Preliminary data collected during the helicopter field testing will also be presented.","PeriodicalId":6295,"journal":{"name":"2007 IEEE Aerospace Conference","volume":"25 1","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2007-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84889041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}