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271.
Tetrahedral Robotics for Space Exploration 总被引:2,自引:0,他引:2
Curtis S. Brandt M. Bowers G. Brown G. Cheung C. Cooperider C. Desch M. Desch N. Dorband J. Gregory K. Lee K. Lunsford A. Minetto F. Truszkowski W. Wesenberg R. Vranish J. Abrahantes M. Clark P. Capon T. Weaker M. Watson R. Olivier P. Rilee M.L. 《Aerospace and Electronic Systems Magazine, IEEE》2007,22(6):22-30
A reconfigurable space filling robotic architecture has a wide range of possible applications. One of the more intriguing possibilities is mobility in very irregular and otherwise impassable terrain. NASA Goddard Space Flight Center is developing the third generation of its addressable reconfigurable technology (ART) tetrahedral robotics architecture. An ART-based variable geometry truss consisting of 12 tetrahedral elements made from 26 smart struts on a wireless network has been developed. The primary goal of this development is the demonstration of a new kind of robotic mobility that can provide access and articulation that complement existing capabilities. An initial set of gaits and other behaviors are being tested, and accommodations for payloads such as sensor and telemetry packages are being studied. Herein, we describe our experience with the ART tetrahedral robotics architecture and the improvements implemented in the third generation of this technology. Applications of these robots to space exploration and the tradeoffs involved with this architecture will be discussed. 相似文献
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273.
Szegö Károly Glassmeier Karl-Heinz Bingham Robert Bogdanov Alexander Fischer Christian Haerendel Gerhard Brinca Armando Cravens Tom Dubinin Eduard Sauer Konrad Fisk Len Gombosi Tamas Schwadron Nathan Isenberg Phil Lee Martin Mazelle Christian Möbius Eberhard Motschmann Uwe Shapiro Vitali D. Tsurutani Bruce Zank Gary 《Space Science Reviews》2000,94(3-4):429-671
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275.
D. Zhou E. Semones R. Gaza S. Johnson N. Zapp K. Lee T. George 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Radiation in low Earth orbit (LEO) is mainly composed of galactic cosmic rays (GCR), solar energetic particles and particles in SAA (South Atlantic Anomaly). The biological impact of space radiation to astronauts depends strongly on the particles’ linear energy transfer (LET) and is dominated by high LET radiation. It is important to measure the LET spectrum for the space radiation field and to investigate the influence of radiation on astronauts. At present, the preferred active dosimeters sensitive to all LET are the tissue equivalent proportional counter (TEPC) and the silicon detectors in various configurations; the preferred passive dosimeters are CR-39 plastic nuclear track detectors (PNTDs) sensitive to high LET and thermoluminescence dosimeters (TLDs) as well as optically stimulated luminescence dosimeters (OSLDs) sensitive to low LET. The TEPC, CR-39 PNTDs, TLDs and OSLDs were used to investigate the radiation field for the ISS mission Expedition 13 (ISS-12S) in LEO. LET spectra and radiation quantities (fluence, absorbed dose, dose equivalent and quality factor) were measured for the space mission with different dosimeters. This paper introduces the role of high LET radiation in radiobiology, the operational principles for the different dosimeters, the LET spectrum method using CR-39 detectors, the method to combine the results measured with TLDs/OSLDs and CR-39 PNTDs, and presents the LET spectra and the radiation quantities measured and combined. 相似文献
276.
Kwangwon Lee Chandeok Park Sang-Young Park Daniel J. Scheeres 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
This study presents a semi-analytic approach for optimal tracking and formation keeping with high precision. For a continuous-thrust propulsion system, optimal formation keeping problems near a general Keplerian orbit are formulated with respect to a reference trajectory which is an explicit function of time. A nonlinear optimal tracking control law is then derived in generic form as a function of the states by employing generating functions in the theory of Hamiltonian systems. The applicability of the overall process is not affected by the complexity of dynamics and the selection of coordinates. As it allows us to design a nonlinear optimal feedback controller in the Earth-centered inertial frame, a variety of nonlinear perturbations can be incorporated easily without complicated coordinate transformations. Numerical experiments demonstrate that the nonlinear tracking control logic achieves superior tracking accuracy and cost reduction by accommodating higher-order nonlinearities. 相似文献
277.
据《航空周刊2020年机队及维修市场预测》,2020年商用飞机、军用飞机、公务机和民用直升机的维修市场总价值为1843亿美元,其中仅商用飞机和军用飞机维修业务就达1658亿美元。但是,预测显示商用飞机产生9120万飞行小时,军用飞机仅产生990万飞行小时,因此军用飞机的飞行小时成本要高得多。而且预计军机维修支出中外场维修占49%,位居首位,其次是零部件、机体和发动机维修。 相似文献
278.
美国航空公司成为全球首家在民用飞机的舱门、安定面、方向舵、升降舵等可更换结构部件上安装具有自动识别(AIT)功能的接触式记忆按钮的航空公司。这种接触式记忆按钮的几何外形只有美元的一角硬币那么大,具有大容量和自动化数据采集等特点,可以帮助航空公司高效地监控飞机可更换结构部件的运营历史,为航空公司节约运营成本、提高数据的精确度。据美国航空公司介绍,在这类结构 相似文献
279.
Yoola Hwang Byoung-Sun Lee Haedong Kim Jaehoon Kim 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
In this paper, Global Positioning System-based (GPS) Orbit Determination (OD) for the KOrea-Multi-Purpose-SATellite (KOMPSAT)-2 using single- and double-differenced methods is studied. The requirement of KOMPSAT-2 orbit accuracy is to allow 1 m positioning error to generate 1-m panchromatic images. KOMPSAT-2 OD is computed using real on-board GPS data. However, the local time of the KOMPSAT-2 GPS receiver is not synchronized with the zero fractional seconds of the GPS time internally, and it continuously drifts according to the pseudorange epochs. In order to resolve this problem, an OD based on single-differenced GPS data from the KOMPSAT-2 uses the tagged time of the GPS receiver, and the accuracy of the OD result is assessed using the overlapping orbit solution between two adjacent days. The clock error of the GPS satellites in the KOMPSAT-2 single-differenced method is corrected using International GNSS Service (IGS) clock information at 5-min intervals. KOMPSAT-2 OD using both double- and single-differenced methods satisfies the requirement of 1-m accuracy in overlapping three dimensional orbit solutions. The results of the SAC-C OD compared with JPL’s POE (Precise Orbit Ephemeris) are also illustrated to demonstrate the implementation of the single- and double-differenced methods using a satellite that has independent orbit information available for validation. 相似文献
280.
Sensitivity analyses of satellite propulsion components with their thermal modelling 总被引:1,自引:0,他引:1
Cho Young Han Jae Ho You Kyun Ho Lee Hui Kyung Kim Sung Nam Lee 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Performing the sensitivity analyses of the contact conduction and the position of thermostat on the basis of the thermal model established, the study of thermal design is accomplished for the preparation of possible mechanical interface change of the satellite propulsion system depending on the satellite system design. A relatively simple thermal model is taken into consideration for the convenience of the analysis. A variety of the spacecraft bus voltages and the contact resistances are examined as well as the position of thermostat on propulsion components. As a consequence, even though the mechanical interface condition is changed on the same module, the successful thermal design could be achieved if we design the heater to have sufficiently large power with reference to the heritage value of contact resistance. Besides the reasonable performance on the thermal control is assured with the thermostat location errors, if the uncertainty in the position of thermostat is not quite large when assembling tank module. 相似文献