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  • 1970-1974  (18)
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Keywords
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Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Lunar orbit determination in the presence of unmodeled accelerations (1974)
    Springer
    Celestial mechanics and dynamical astronomy 9 (1974), S. 191-211 
    Details
    ISSN: 1572-9478
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A technique for estimating the state of an artificial satellite in the presence of unmodeled accelerations is presented. The unmodeled acceleration is approximated by a first-order Gauss-Markov sequence which can be separated into a timewise correlated component and a purely random component. Using this approximation, a sequential procedure for estimating the position, velocity, and the unmodeled acceleration is developed. The method is evaluated by reducing range-rate observations obtained by tracking the Apollo 10 and 11 spacecraft during the lunar orbit phase of the mission. Numerical results are presented which show that the observation residual pattern lies within the observation noise standard deviation. The values of the estimated components of the unmodeled acceleration are repeatable from orbit to orbit within a given mission and from mission to mission when the same ground track is covered. Finally, the variation in the radial component of the unmodeled acceleration shows a high correlation with the reported location of the lunar surface mascons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01260513
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    An extended canonical perturbation method (1973)
    Springer
    Celestial mechanics and dynamical astronomy 7 (1973), S. 77-90 
    Details
    ISSN: 1572-9478
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this investigation, a procedure is described for extending the application of canonical perturbation theories, which have been applied previously to the study of conservative systems only, to the study of non-conservative dynamical systems. The extension is obtained by imbedding then-dimensional non-conservative motion in a 2n-dimensional space can always be specified in canonical form, and, consequently, the motion can be studied by direct application of any canonical perturbation method. The disadvantage of determining a solution to the 2n-dimensional problem instead of the originaln-dimensional problem is minimized if the canonical transformation theory is used to develop the perturbation solution. As examples to illustrate the application of the method, Duffing's equation, the equation for a linear oscillator with cubic damping and the van der Pol equation are solved using the Lie-Hori perturbation algorithm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01243509
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    Paper (German National Licenses)
    Fulltext
  • 3
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    Lunar orbit determination in the presence of unmodeled accelerations (1974)
    Springer
    Details
    Publication Date: 1974-04-01
    Print ISSN: 0923-2958
    Electronic ISSN: 1572-9478
    Topics: Physics
    Published by Springer
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    PAPER CURRENT
  • 4
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    An extended canonical perturbation method (1973)
    Springer
    Details
    Publication Date: 1973-01-01
    Print ISSN: 0923-2958
    Electronic ISSN: 1572-9478
    Topics: Physics
    Published by Springer
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    PAPER CURRENT
  • 5
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    The computation of optimal control programmes using a modified successive sweep method. (1972)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A second-order method for numerically solving control optimization problems has been developed. The method, referred to as the modified sweep method (MSM), differs from the successive sweep method (SSM) proposed by McReynolds and Bryson (1965) in that the conditions for local control optimality are used to determine the control as an explicit function of the state variables and time. The control is eliminated from the problem and the solution to the resulting two-point boundary value problem can be obtained by linear perturbation methods. The modified sweep method proposed here uncouples the perturbation equations for the state variables and the Lagrange multipliers by using a generalized matrix-Riccati transformation of variables. The resulting algorithm for the numerical iteration process is concerned with determining the initial values of a set of Lagrange multipliers rather than correcting a numerical control programme over the entire time interval of interest.
    Keywords: SPACE VEHICLES
    Type: International Journal of Control; vol. 15
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Navigation strategy and filter design for solar electric missions (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Methods which have been proposed to improve the navigation accuracy for the low-thrust space vehicle include modifications to the standard Sequential- and Batch-type orbit determination procedures and the use of inertial measuring units (IMU) which measures directly the acceleration applied to the vehicle. The navigation accuracy obtained using one of the more promising modifications to the orbit determination procedures is compared with a combined IMU-Standard. The unknown accelerations are approximated as both first-order and second-order Gauss-Markov processes. The comparison is based on numerical results obtained in a study of the navigation requirements of a numerically simulated 152-day low-thrust mission to the asteroid Eros. The results obtained in the simulation indicate that the DMC algorithm will yield a significant improvement over the navigation accuracies achieved with previous estimation algorithms. In addition, the DMC algorithms will yield better navigation accuracies than the IMU-Standard Orbit Determination algorithm, except for extremely precise IMU measurements, i.e., gyroplatform alignment .01 deg and accelerometer signal-to-noise ratio .07. Unless these accuracies are achieved, the IMU navigation accuracies are generally unacceptable.
    Keywords: NAVIGATION
    Type: NASA-CR-127860 , AMRL-1040
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    A modified perturbation method for solving optimal control problems with state variable inequality constraints (1971)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Modified perturbation method for solving optimal control boundary value problems with state variable inequality constraints, noting application to reentry trajectories
    Keywords: SPACE VEHICLES
    Type: ; ADEMIE DES SCIENCES
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Lunar orbit determination in the presence of unmodeled accelerations (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A technique for estimating the state of an artificial satellite in the presence of unmodeled accelerations is presented. The unmodeled acceleration is approximated by a first-order Gauss-Markov sequence which can be separated into a timewise-correlated component and a purely random component. Using this approximation, a sequential procedure for estimating the position, velocity, and the unmodeled acceleration is developed. The method is evaluated by reducing range-rate observations obtained by tracking the Apollo 10 and 11 spacecraft during the lunar-orbit phase of the mission. Numerical results are presented which show that the observation residual pattern lies within the observation noise standard deviation. The values of the estimated components of the unmodeled acceleration are repeatable from orbit to orbit within a given mission and from mission to mission when the same ground track is covered. Finally, the variation in the radial component of the unmodeled acceleration shows a high correlation with the reported location of the lunar surface mascons.
    Keywords: SPACE SCIENCES
    Type: Celestial Mechanics; 9; Apr. 197
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Guidance methods for low-thrust space vehicles Cumulative progress report, 1 Jan. 1969 - 31 Jan. 1970 (1970)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Guidance and control schemes for optimal low-thrust Earth-Mars transfer missions
    Keywords: NAVIGATION
    Type: NASA-CR-108235
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Sequential estimation of the state and the observation-error convariance matrix (1971)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Algorithm for simultaneous estimate of spacecraft state and covariance matrix with observation error vector
    Keywords: MATHEMATICS
    Type: ; VUE SCIENTIFIQUE ET
    Format: text
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