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Stable and verifiable state estimation methods and systems with spacecraft applications

  • US 6,317,662 B1
  • Filed: 07/24/2000
  • Issued: 11/13/2001
  • Est. Priority Date: 07/24/2000
  • Status: Expired due to Term
First Claim
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1. A method of enhancing the stability of a recursive estimator process that generates estimates X*(tn+) of state parameters X(tn) of a system from measurements Y(tn) wherein tn represents successive times and tn+ represents times that each lag a respective one of said successive times tn, said method comprising the steps of:

  • generating at least one measurement Y(tn);

    with an error covariance P(tn) and a measurement-noise covariance R(tn) of said process, calculating a gain K(tn);

    processing said measurement Y(tn) with the aid of said gain K(tn) to generate at least one estimate X*(tn+);

    recursively repeating said generating, calculating and processing steps to reduce said error covariance P(tn) to operational values Po that are not substantially reduced with further recursion; and

    periodically resetting said error covariance P(tn) to a reset value Pr that exceeds said operational values Po to thereby reset said calculating step and enhance said stability.

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