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  • 1
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    Large Space Telescope oscillations induced by CMG friction (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Conditions are predicted under which limit cycles may be caused by the friction torque of the control moment gyroscope (CMG) output gimbal used in the Large Space Telescope (LST). The parameter plane analysis technique is described, and three separate models of the CMG output friction nonlinearity are used in three separate analyses. The results suggest that the Dahl model (included in model 3) is the best available friction model for use in dynamic analysis. The analysis and analog simulation indicate the absence of limit cycle behavior due to the CMG output gimbal friction nonlinearity for presently estimated LST numerical parameters and the occurrence of one stable and one unstable limit cycle if substantially larger numerical values are allowed for the CMG gimbal pivot friction parameter and/or the running friction torque.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Spacecraft and Rockets; 12; Feb. 197
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Electron, electron-bremsstrahlung and proton depth-dose data for space-shielding applications (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A data set has been developed, consisting of depth-dose distributions for omni-directional electron and proton fluxes incident on aluminum shields. The principal new feature of this work is the accurate treatment, based on detailed Monte Carlo calculations, of the electron-produced bremsstrahlung component. Results covering the energy region of interest in space-shielding calculations have been obtained for the absorbed dose (a) as a function of depth in a semi-infinite medium, (b) at the edge of slab shields, and (c) at the center of a solid sphere. The dose to a thin tissue-equivalent detector was obtained as well as that in aluminum. Various results and comparisons with other work are given.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    NASA/MSFC ground experiment for large space structure control verification (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Marshall Space Flight Center has developed a facility in which closed loop control of Large Space Structures (LSS) can be demonstrated and verified. The main objective of the facility is to verify LSS control system techniques so that on orbit performance can be ensured. The facility consists of an LSS test article which is connected to a payload mounting system that provides control torque commands. It is attached to a base excitation system which will simulate disturbances most likely to occur for Orbiter and DOD payloads. A control computer will contain the calibration software, the reference system, the alignment procedures, the telemetry software, and the control algorithms. The total system will be suspended in such a fashion that LSS test article has the characteristics common to all LSS.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-86496 , NAS 1.15:86496
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    An application of high authority/low authority control and positivity (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Control Dynamics Company (CDy), in conjunction with NASA Marshall Space Flight Center (MSFC), has supported the U.S. Air Force Wright Aeronautical Laboratory (AFWAL) in conducting an investigation of the implementation of several DOD controls techniques. These techniques are to provide vibration suppression and precise attitude control for flexible space structures. AFWAL issued a contract to Control Dynamics to perform this work under the Active Control Technique Evaluation for Spacecraft (ACES) Program. The High Authority Control/Low Authority Control (HAC/LAC) and Positivity controls techniques, which were cultivated under the DARPA Active Control of Space Structures (ACOSS) Program, were applied to a structural model of the NASA/MSFC Ground Test Facility ACES configuration. The control systems design were accomplished and linear post-analyses of the closed-loop systems are provided. The control system designs take into account effects of sampling and delay in the control computer. Nonlinear simulation runs were used to verify the control system designs and implementations in the facility control computers. Finally, test results are given to verify operations of the control systems in the test facility.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-100338 , NAS 1.15:100338
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Cost effective development of a national test bed (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: For several years, the Marshall Space Flight Center has pursued the coordinated development of a Large Space Structures (LSS) National Test Bed for the investigation of numerous technical issues involved in the use of LSS in space. The origins of this development, the current status of the various test facilities and the plans laid down for the next five years' activities are described. Particular emphasis on the control and structural interaction issues has been paid so far; however, immediately emerging are user applications (such as the proposed pinhole occulter facility). In the immediate future, such emerging technologies as smart robots and multibody interactions will be studied. These areas are covered.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-100321 , NAS 1.15:100321
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Flight performance of Skylab attitude and pointing control system (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The Skylab attitude and pointing control system (APCS) requirements are briefly reviewed and the way in which they became altered during the prelaunch phase of development is noted. The actual flight mission (including mission alterations during flight) is described. The serious hardware failures that occurred, beginning during ascent through the atmosphere, also are described. The APCS's ability to overcome these failures and meet mission changes are presented. The large around-the-clock support effort on the ground is discussed. Salient design points and software flexibility that should afford pertinent experience for future spacecraft attitude and pointing control system designs are included.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TN-D-8003 , M-136
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    A satellite digital controller or 'play that PID tune again, Sam' (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The problem discussed is to design a digital controller for a typical satellite. The controlled plant is considered to be a rigid body acting in a plane. The controller is assumed to be a digital computer which, when combined with the proposed control algorithm, can be represented as a sampled-data system. The objective is to present a design strategy and technique for selecting numerical values for the control gains (assuming position, integral, and derivative feedback) and the sample rate. The technique is based on the parameter plane method and requires that the system be amenable to z-transform analysis.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 76-1947 , Guidance and Control Conference; Aug 16, 1976 - Aug 18, 1976; San Diego, CA
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Specifying spacecraft flexible appendage rigidity (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: As a method for specifying the required degree of rigidity of spacecraft flexible appendages, an analytical technique is proposed for establishing values for the frequency, damping ratio, and modal gain (deflection) of the first several bending modes. The shortcomings of the technique result from the limitations associated with the order of the equations that can be handled practically. An iterative method is prescribed for handling a system whose structural flexibility is described by more than one normal mode. The analytical technique is applied to specifying solar panel rigidity constraints for the NASA Space Telescope. The traditional nonanalytic procedure for specifying the required degree of rigidity of spacecraft flexible appendages has been to set a lower limit below which bending mode frequencies may not lie.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 77-1098 , Guidance and Control Conference; Aug 08, 1977 - Aug 10, 1977; Hollywood, FL
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Stability analysis of the discrete-data Large-Space-Telescope system (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: This paper considers the application of the discrete describing function to the stability analysis of the Large-Space Telescope (LST) system. An analytical model of the CMG gimbal friction is derived, which is then used to arrive at a closed-form analytical expression for the discrete describing function of the nonlinearity. The analysis is used for the study of the fine-pointing stability of the LST vehicle. Simulation results corroborate the conclusions from the analytical analysis.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Spacecraft and Rockets; 13; June 197
    Format: text
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  • 10
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    Definition of ground test for verification of large space structure control (1985)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Directions regarding the analytical models were received. A counter balance arm with weights was added at the top of the ASTROMAST to offset the arm with the gimbals. In addition to this model, three more models were requested from MSFC: structure as in the revised model with the addition of lumped masses at bays 46 and 91 of the ASTROMAST; cantilevered cruciform structure with lumped masses at bays 46 and 91, and an all up cruciform structure with lumped masses at bays 46 and 91. Figures for each model and their corresponding natural frequencies and general mode shapes associated with these frequencies are included. The drawbar in use in the cruciform models must be incorporated into the antenna and ASTROMAST models. The total tensile load carrying capability of the ASTROMAST is approximately 840 pounds.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-171438 , NAS 1.26:171438 , PR-10
    Format: application/pdf
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