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84 lines
2.8 KiB
C
84 lines
2.8 KiB
C
/**
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******************************************************************************
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*
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* @file paths.c
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
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* @brief Library path manipulation
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*
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* @see The GNU Public License (GPL) Version 3
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*
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*****************************************************************************/
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "pios.h"
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#include "paths.h"
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/**
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* @brief Compute progress along path and deviation from it
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* @param[in] start_point Starting point
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* @param[in] end_point Ending point
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* @param[in] cur_point Current location
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* @param[out] status Structure containing progress along path and deviation
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*/
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void path_progress(float * start_point, float * end_point, float * cur_point, struct path_status * status)
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{
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float path_north, path_east, diff_north, diff_east;
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float dist_path2;
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float dot;
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float normal[2];
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// Distance to go
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path_north = end_point[0] - start_point[0];
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path_east = end_point[1] - start_point[1];
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// Current progress location relative to start
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diff_north = cur_point[0] - start_point[0];
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diff_east = cur_point[1] - start_point[1];
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dot = path_north * diff_north + path_east * diff_east;
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dist_path2 = path_north * path_north + path_east * path_east;
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if(dist_path2 < 1e-3) {
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status->fractional_progress = 1;
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status->error = 0;
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status->correction_direction[0] = status->correction_direction[1] = 0;
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status->path_direction[0] = status->path_direction[1] = 0;
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return;
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}
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// Compute the normal to the path
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normal[0] = -path_east / sqrtf(dist_path2);
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normal[1] = path_north / sqrtf(dist_path2);
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status->fractional_progress = dot / dist_path2;
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status->error = normal[0] * diff_north + normal[1] * diff_east;
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// Compute direction to correct error
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status->correction_direction[0] = (status->error > 0) ? -normal[0] : normal[0];
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status->correction_direction[1] = (status->error > 0) ? -normal[1] : normal[1];
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// Now just want magnitude of error
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status->error = fabs(status->error);
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// Compute direction to travel
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status->path_direction[0] = path_north / sqrtf(dist_path2);
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status->path_direction[1] = path_east / sqrtf(dist_path2);
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status->error = fabs(status->error);
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}
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