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  • 1
    Publication Date: 2011-08-24
    Description: A method is presented by which measured modes and frequencies from a modal test can be used to determine the location and magnitude of damage in a space struss structure. The damage is located by computing the Euclidean distances between the measured mode shapes and the best achievable eigenvectors. The best achievable eigenvectors are the projection of the measured mode shapes onto the subspace defined by the refined analytical model of the structure and the measured frequencies. Loss of both stiffness and mass properties can be located and quantified. To examine the performance of the method when experimentally measured modes are employed, various damage detection studies using a laboratory eight-bay truss structure were conducted. The method performs well even though the measurement errors inevitably make the damage location more difficult.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA Journal (ISSN 0001-1452); 32; 5; p. 1049-1057
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  • 2
    Publication Date: 2011-08-24
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 15; 6; p. 1427-1433.
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  • 3
    Publication Date: 2011-08-24
    Description: The design, analysis, and simulation of a control law that guarantees a fine pointing performance under external disturbances and model uncertainties are investigated. The authors examine the achievable performance and modeling errors for the control-structure interaction (CSI) evolutionary model structure and highlight the importance of accurate knowledge of structural frequencies and damping values for very lightly damped structures. Numerical results indicate that a limited but significant line-of-sight pointing performance robustness can be attained in spite of modeled structured and unstructured uncertainties in the system. The simulation results reported demonstrate typical performance levels, types of uncertainties and their magnitudes, and design tradeoffs for a realistic laboratory model of a large flexible space structure.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: In: 1992 American Control Conference, 11th, Chicago, IL, June 24-26, 1992, Proceedings. Vol. 3 (A93-22776 07-63); p. 1996-2000.
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  • 4
    Publication Date: 2011-08-24
    Description: The Magellan spacecraft has been aerobraked into a 197 x 541 km near-circular orbit around Venus from which it is conducting a high-resolution gravity mapping mission. This was the first interplanetary aerobrake maneuver and involved flying the spacecraft through the upper reaches of the Venusian atmosphere 730 times over a 70 day period. Round-trip light-time varied from 9.57 to 18.83 minutes during this period. Navigation for this dynamic phase of the Magellan mission was planned and executed in the face of budget-driven down-sizing with all spacecraft safe modes disabled and a flight-team one-third the size of comparable interplanetary missions. Successful execution of this manuever using spacecraft hardware not designed to operate in a planetary atmosphere, demonstrated a practical cost-saving technique for both large and small future interplanetary missions.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: British Interplanetary Society, Journal (ISSN 0007-094X); 48; 3; p. 111-122
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  • 5
    Publication Date: 2011-08-24
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 15; 49-57
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  • 6
    Publication Date: 2013-08-31
    Description: Large orbiting space structures are expected to experience mechanical vibrations arising from several disturbing forces such as those induced by shuttle takeoff or docking and crew movements. The problem is considered of modeling and control of large space structures subject to these and other disturbing forces. The system consists of a (rigid) massive body, which may play the role of experimental modules located at the center of the space station and flexible configurations, consisting of several beams, forming the space structure. A complete dynamic model of the system was developed using Hamilton's principle. This model consists of radial equations describing the translational motion of the central body, rotational equations describing the attitude motions of the body and several beam equations governing the vibration of the flexible members (platform) including appropriate boundary conditions. In summary, the dynamics of the space structure is governed by a complex system of interconnected partial and ordinary differential equations. Using Lyapunov's approach the asymptotic stability of the space structure is investigated. For asymptotic stability of the rest state (nominal trajectory), feedback controls are suggested. In the investigation, stability of the slewing maneuvers is also considered. Several numerical results are presented for illustration of the impact of coupling and the effectiveness of the stabilizing controls. Some insight is provided into the complexity of modeling, analysis and stabilization of actual space structures.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Jet Propulsion Lab., California Inst. of Tech., Proceedings of the 3rd Annual Conference on Aerospace Computational Control, Volume 2; p 900-914
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  • 7
    Publication Date: 2019-06-28
    Description: One concept for a manned mission to Mars uses as a transportation mode an evolutionary version of Space Station Freedom (SSF), termed the Mars Evolution Reference Configuration (MERC). The MERC is configured by adding to SSF dual keels, an upper and lower boom, additional laboratory and habitation modules, increased power, and an assembly platform. A finite-element model of the MERC was formulated to investigate the expected low frequency modes, and its variations with the addition of large payload. A basic reboost procedure using near-continuous firing of reaction control system jets is described with the closed-loop attitude control system. The elastic dynamic behavior at critical points during a reboost of the MERC, both with and without the Mars piloted vehicle installed, is examined.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 90-0746
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  • 8
    Publication Date: 2019-06-28
    Description: In the current design, the Space Station first-flight configuration will be assembled in a LEO and reboosted to a higher altitude such that the orbital decay due to atmospheric drag forces will lower the spacecraft to the proper altitude at the appropriate time to rendezvous with the next-assembly flight of the orbiter. The reboost maneuver will be performed by firing the on/off reaction control system jets to increase the forward velocity. This paper describes the design of a basic orbital reboost maneuver based on a burn-coast-burn scenario and a closed-loop attitude control system which will control the firing sequences of the jets to maintain the spacecraft attitude within required bounds. The design is then used to investigate the infuence of the elastic component response on the reboost jet firing logic.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 90-0747
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  • 9
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: This paper is concerned with the vibration control of the SCOLE structure while it undergoes a slewing maneuver. The control law is designed according to the linear quadratic regulator theory. In view of saturation limits on the actuators, the actual implementation is modified so as to observe these limits, resulting in suboptimal control. State estimation is carried out by means of a Kalman filter. The control and state estimation are carried out in discrete time. Numerical simulations for several cases of interest are presented.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: In: Dynamics and control of large structures; Proceedings of the 8th VPI&SU Symposium, Blacksburg, VA, May 6-8, 1991 (A93-29328 10-63); p. 757-772.
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  • 10
    Publication Date: 2019-07-13
    Description: A method of finding the optimal sensor and actuator locations for the control of flexible structures has been developed. The method is based on the orthogonal projection of structural modes into the intersection subspace of the controllable and observable subspaces. The controllability and observability grammians are then used to weight the projections to reflect the degrees of controllability and observability. This method produces a three-dimensional design space wherein sets of optimal actuator and sensors may be selected.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 90-3466 , AIAA Guidance, Navigation and Control Conference; Aug 20, 1990 - Aug 22, 1990; Portland, OR; United States
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