46 lines
2.3 KiB
TeX
46 lines
2.3 KiB
TeX
\section{Ball approach}
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\subsection{Approach from the Side}
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The first possibility is that in the approach planing stage, described in the
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section \ref{j sec approach planing}, the decision was taken to approach the
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ball from the side. In this case the robot will walk the calculated distance in
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the calculated direction. Normally, after the movement the robot should lose
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the sight of the ball. However, the approximate angle, where the ball should be
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relative to the robot after the movement, is known. Therefore, the robot will
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rotate by that angle and will then try to detect the ball and turn to it, using
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the \textbf{Turn to Ball} algorithm, described in the section \ref {j sec turn
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to ball}. Once this was done, the approach planning stage is repeated.
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Normally, the distance to the ball should now be small, and the ball and the
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goal should lie in the same direction, which means that only short direct
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approach at this point will be necessary. That might not always be the case, so
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in rare situations another step of the approach from the side might be
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necessary.
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\begin{figure}[ht]
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\includegraphics[width=\textwidth]{\fig after-sideways}
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\caption{After approach from the side}
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\label{p figure after-sideways}
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\end{figure}
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\subsection{Direct Approach}
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It is also possible that the decision will be taken to approach the ball
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directly, either from the start or after the robot already has approached the
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ball from the side. In this stage the robot will walk towards the ball trying
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to stay centered at it. To do so, it will be constantly checked that the ball
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stays within some tolerance angle from the center of the camera frame. If the
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ball moves from the center further than by some tolerance angle, then the robot
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will stop moving, will adjust the movement direction and then will go further.
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The robot will continue moving until the ball is close enough to start the goal
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alignment. Do determine if that is the case, we don't use trigonometry, but
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simply define a threshold, which the image of the ball in the robot's lower
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camera should reach. Once this happened, the approach stage is over and the
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robot will start aligning itself to the goal.
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\begin{figure}[ht]
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\includegraphics[width=\textwidth]{\fig direct-approach}
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\caption{Approach termination condition}
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\label{p figure direct-approach}
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\end{figure}
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