104 lines
2.9 KiB
TeX
104 lines
2.9 KiB
TeX
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% `HeadingHold.tex' -- describes the FGFS Heading Hold
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% Written by Jeff Goeke-Smith
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% $Id$
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%------------------------------------------------------------------------
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\documentclass[12pt]{article}
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\usepackage{anysize}
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\papersize{11in}{8.5in}
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\marginsize{1in}{1in}{1in}{1in}
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\usepackage{amsmath}
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\usepackage{epsfig}
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\usepackage{setspace}
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\onehalfspacing
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\usepackage{url}
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\begin{document}
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\title{
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Flight Gear Autopilot: \\
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Heading Hold Module
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}
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\author{
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Jeff Goeke-Smith \\
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(\texttt{jgoeke@voyager.net})
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}
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\maketitle
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\section{Heading Hold}
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The first autopilot system implemented was a heading hold system. The
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entire point of the system was to hold a single heading by using the
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ailerons only. Currently the system does not use the rudder for
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heading or side slip control. The system of determining how to
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control the ailerons is a fuzzy logic system ( at least according to
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the book I borrowed from the local library) .
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The first stage of the autopilot system determines the relative
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heading by comparing the current heading to the target heading. This
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step allows me to determine what direction I should turn.
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\begin{figure}[hbt]
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\centerline{
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\psfig{file=HeadingHold.eps}
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}
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\caption{Relative heading vs. target roll}
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\label{fig:headinghold}
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\end{figure}
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The next step determines how far I should be rolled and in what
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direction. By luck, or maybe by design, If I want to move to a
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negative relative heading, I need to have a negative roll. And by even
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more luck, To roll in a negative direction, I need to add negative
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aileron. Figure \ref{fig:headinghold} shows how I determine how far I
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should be rolled. The x-axis represents the relative heading. The
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y-axis represents the Target Roll. The specific values where the
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graph changes slope is determined by a series of variables in the
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Autopilot Structure.
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% ___________________________
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% /
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% /
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%0- - - - - - - - - - - - / - - - - - - - - - - - -
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% /
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%_______________________/
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%| | |
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%-180 0 180
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Now that the we know how far the aircraft should be rolled, we now
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determine the Relative roll. This being the current roll compared to
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the target roll. Now that we know how far we need to roll, we employ
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a near identical copy of the above routine to determine where the
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aileron should be by using the x-axis to represent the relative roll
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and the y-axis being the aileron setting. The system then sets the
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aileron to that setting and finishes the procedure.
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If anyone who reads this is interested in more information on how I
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built this system, feel free to e-mail me at
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\texttt{jgoeke@voyager.net} or read the code yourself.
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\end{document}
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%------------------------------------------------------------------------
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