Heading Error

Today we noticed that Cook's flight patterns are not as smooth as we would like.  The plots below show the glider's heading error at the peak of each climb and dive.  The scale illustrates only 45 degrees in either direction, but when plotted on a larger scale it can be seen that Cook turns up to 100 degrees away from his expected path.  Cook is capable of correcting himself, but it takes about a quarter of the dive to get back on a straight track.  If this problem can be resolved, we should be able to increase the glider's velocity.

One Response to “Heading Error”

  1. Antonio G. RAMOS Says:

    Hey all !

    The heading error is presented since cook began to swim...

    (http://marine.rutgers.edu/~kerfoot/imagery/auvs/cook/segments).

    WE HAVE at home (ULPGC) 3 SPECULATIONS about

    1. HEADING ERROR LOOKS CLEARLY ASSOCIATED TO THE FLOTABILITY. It could be associated to the creation of a force pair (WHEN THE PUMP ACTIVATES) that causes an angular movement (rigth or left) on cook. It could explain the regularity of the left-right error vs climbing-ascending (when the pump changes the gravity centre of cook).

    2.- Cook IS MORE STABLE WHEN CLIMBS. If the heading error were affected by and increase of its dragging coefficient (barnacles fan club), a similar behaviour during climbing/diving could be expected.. or at least, an apparently, randomic heading error time serie.

    > 3. The PITCH CURVE presents a LITTLE DEFORMATION. The pitch angle increase witth pressure,especially during the diving.

    > http://www.i-cool.org/wp-content/uploads/2010/06/June-15-PRH1.png ,

    A little deformation on the nose is enough to move the gravity centre forward increasing the pitch angle..

    This explanation would be possible if there is not any pitch correction and the error is lower than the dead angle assumed as "not significant effect on navigation".

    It would be interesting to get the numeric data to validate these especulations with a numeric model.

    The artist : J Cabrera/D Hernandez (ULPGC team).

    greetings

    antonio

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