Aerospace Engineering Research Works

Permanent URI for this collectionhttp://hdl.handle.net/1903/1655

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Now showing 1 - 6 of 6
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    Speed and Accuracy Tests of the Variable-Step Störmer-Cowell Integrator
    (Univelt, Inc., 2005-02) Berry, Matthew M.; Healy, Liam M.
    The variable-step Stormer-Cowell integrator is a non-summed, double-integration multi-step integrator derived in variable-step form. The method has been implemented with a Shampine-Gordon style error control algorithm that uses an approximation of the local error at each step to choose the step size for the subsequent step. In this paper, the variable-step Stormer-Cowell method is compared to several other multi-step integrators, including the fixed-step Gauss-Jackson method, the Gauss-Jackson method with s-integration, and the variable-step single-integration Shampine- Gordon method, in both orbit propagation and orbit determination. The results show the variable-step Stormer-Cowell method is comparable with Gauss-Jackson using s-integration, except in high drag cases where the variable-step Stormer-Cowell method has an advantage in speed and accuracy.
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    Accuracy and Speed Effects of Variable Step Integration for Orbit Determination and Propagation
    (Univelt, Inc., 2003-08) Berry, Matthew M.; Healy, Liam M.
    In this paper the fixed step Gauss-Jackson method is compared to two variable step integrators. The first is the variable step, variable order Shampine-Gordon method. The second is s-integration, which may be considered an analytical step regulation. Speed tests are performed for orbit propagation with the integrators set to give equivalent accuracy. The integrators are also tested for orbit determination, to determine the speed benefit of the variable step methods. The tests give an indication of the types of orbits where variable step methods are more efficient than fixed step methods.
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    Orbit propagation with Lie transfer maps in the perturbed Kepler problem
    (Springer Science+Business Media B.V., 2003-02) Healy, Liam M.
    The Lie transfer map method may be applied to orbit propagation problems in celestial mechanics. This method, described in another paper, is a perturbation method applicable to Hamiltonian systems. In this paper, it is used to calculate orbits for zonal perturbations to the Kepler (two-body) problem, in both expansion in the eccentricity and closed form. In contrast with a normal form method like that of Deprit, the Lie transformations here are used to effect a propagation of phase space in time, and not to transform one Hamiltonian into another.
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    Comparison Of Accuracy Assessment Techniques For Numerical Integration
    (Univelt, Inc., 2003-02) Berry, Matt; Healy, Liam
    Knowledge of accuracy of numerical integration is important for composing an overall numerical error budget; in orbit determination and propagation for space surveillance, there is frequently a computation time-accuracy tradeoff that must be balanced. There are several techniques to assess the accuracy of a numerical integrator. In this paper we compare some of those techniques: comparison with two-body results, with step-size halving, with a higher-order integrator, using a reverse test, and with a nearby exactly integrable solution (Zadunaisky's technique). Selection of different kinds of orbits for testing is important, and an RMS error ratio may be constructed to condense results into a compact form. Our results show that step- size halving and higher-order testing give consistent results, that the reverse test does not, and that Zadunaisky's technique performs well with a single-step integrator, but that more work is needed to implement it with a multi-step integrator.
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    The generalized Sundman transformation for propagation of high-eccentricity elliptical orbits
    (Univelt, Inc., 2002-01) Berry, Matthew M.; Healy, Liam M.
    A generalized Sundman transformation dt = cr^n ds for exponent n >= 1 may be used to accelerate the numerical computation of high-eccentricity orbits, by transforming time t to a new independent variable s. Once transformed, the integration in uniform steps of s effectively gives analytic step variation in t with larger time steps at apogee than at perigee, making errors at each point roughly comparable. In this paper, we develop techniques for assessing accuracy of s-integration in the presence of perturbations, and analyze the effectiveness of regularizing the transformed equations. A computational speed comparison is provided.
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    Implementation of Gauss-Jackson Integration for Orbit Propagation
    (American Astronautical Society, 2004) Berry, Matthew M.; Healy, Liam M.
    The Gauss-Jackson multi-step predictor-corrector method is widely used in numerical integration problems for astrodynamics and dynamical astronomy. The U.S. space surveillance centers have used an eighth-order Gauss-Jackson algorithm since the 1960s. In this paper, we explain the algorithm including a derivation from first principals and its relation to other multi-step integration methods. We also study its applicability to satellite orbits including its accuracy and stability.