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Tracking system for tracking targets with a spacecraft

  • US 5,400,033 A
  • Filed: 02/07/1994
  • Issued: 03/21/1995
  • Est. Priority Date: 02/07/1994
  • Status: Expired due to Fees
First Claim
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1. A tracking system for tracking a target with a spacecraft, comprising:

  • at least one integral pulse frequency modulation reaction jet control system for tracking the target with small tracking errors,said at least one reaction jet control system comprising;

    a) means for utilizing target trajectory data (rT) and spacecraft trajectory data (rS) to determine line of sight trajectory data lI ; and

    line of sight rate lI ;

    b) means for determining spacecraft attitude command (Θ

    C) and rate command (ω

    C) utilizing said lI and said lI ;

    c) means for utilizing said (Θ

    C) and (ω

    C) in conjunction with actual attitude signals (Θ

    ) and rate signals (ω

    ) of said spacecraft for determining spacecraft attitude error (Θ

    e) and error (ω

    e);

    d) means for multiplying said ω

    e with a diagonal rate gain matrix (KD), and adding the resultant value, KD ω

    e, to said Θ

    e to provide a combined error e;

    e) means for integrating said e and comparing the integrated combined error (eI) with a threshold vector (AI), jets of said spacecraft being turned on about an axis if the corresponding element of said (eI) exceeds the corresponding element of said AI, said previous steps being repeated if any element of said AI exceeds the corresponding element of said eI ; and

    f) means for zeroing any element of eI whenever it exceeds the corresponding element of AI and starting its integration afresh, repeating the above steps.

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