• Author: Urbina Diego
  • Description:

    Star Trackers are devices that provide higher accuracy than other attitude sensors
    with the added bene ts of 3-axis attitude determination. Nevertheless, Star Trackers
    are frequently heavy, complex and costly systems that can not be adopted by small
    satellites such as the Aramis from Politecnico di Torino, which needs high-accuracy
    attitude determination to cover the requirements of certain types of payload.
    In this thesis, the state of the art in attitude sensing is described, specially that
    of Star Trackers. Then, a preliminary design of a low-mass, low-cost, low-power and
    coarse accuracy Star Tracker is proposed to satisfy the requirements of the Aramis
    Di erent available algorithms for identifying the presence of single stars on the
    imager plane are analyzed, as well as those for pattern recognition necessary to
    ultimately measure the spacecraft attitude. One set of such image processing and
    pattern recognition algorithms are chosen for use on board Aramis. Subsequently,
    they are tested with the experimental use of the 3D open source planetarium Celestia,
    while a parallel test of the image processing algorithms is performed on real
    star eld imagery to con rm their capabilities with real-world data.
    A scheme is proposed to reduce the amount of false results thanks to the use
    of attitude approximations coming from other sensors, through the homogeneous
    segmentation of the celestial sphere.
    Commonly used methods to produce the desired quaternion output are described,
    and nally, an assessment of the performance of the tested algorithms is made.

  • Year: 2008
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