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256 lines
8.8 KiB
C
256 lines
8.8 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 <pios_math.h>
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#include "paths.h"
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#include "uavobjectmanager.h" // <--.
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#include "pathdesired.h" // <-- needed only for correct ENUM macro usage with path modes (PATHDESIRED_MODE_xxx,
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// no direct UAVObject usage allowed in this file
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// private functions
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static void path_endpoint(float *start_point, float *end_point, float *cur_point, struct path_status *status);
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static void path_vector(float *start_point, float *end_point, float *cur_point, struct path_status *status);
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static void path_circle(float *start_point, float *end_point, float *cur_point, struct path_status *status, bool clockwise);
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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[in] mode Path following mode
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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, uint8_t mode)
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{
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switch (mode) {
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case PATHDESIRED_MODE_FLYVECTOR:
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case PATHDESIRED_MODE_DRIVEVECTOR:
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return path_vector(start_point, end_point, cur_point, status);
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break;
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case PATHDESIRED_MODE_FLYCIRCLERIGHT:
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case PATHDESIRED_MODE_DRIVECIRCLERIGHT:
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return path_circle(start_point, end_point, cur_point, status, 1);
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break;
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case PATHDESIRED_MODE_FLYCIRCLELEFT:
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case PATHDESIRED_MODE_DRIVECIRCLELEFT:
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return path_circle(start_point, end_point, cur_point, status, 0);
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break;
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case PATHDESIRED_MODE_FLYENDPOINT:
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case PATHDESIRED_MODE_DRIVEENDPOINT:
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default:
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// use the endpoint as default failsafe if called in unknown modes
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return path_endpoint(start_point, end_point, cur_point, status);
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break;
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}
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}
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/**
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* @brief Compute progress towards endpoint. Deviation equals distance
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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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static void path_endpoint(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_path, dist_diff;
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// we do not correct in this mode
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status->correction_direction[0] = status->correction_direction[1] = 0;
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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 end
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diff_north = end_point[0] - cur_point[0];
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diff_east = end_point[1] - cur_point[1];
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dist_diff = sqrtf(diff_north * diff_north + diff_east * diff_east);
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dist_path = sqrtf(path_north * path_north + path_east * path_east);
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if (dist_diff < 1e-6f) {
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status->fractional_progress = 1;
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status->error = 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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status->fractional_progress = 1 - dist_diff / (1 + dist_path);
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status->error = dist_diff;
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// Compute direction to travel
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status->path_direction[0] = diff_north / dist_diff;
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status->path_direction[1] = diff_east / dist_diff;
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}
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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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static void path_vector(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_path;
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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_path = sqrtf(path_north * path_north + path_east * path_east);
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if (dist_path < 1e-6f) {
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// if the path is too short, we cannot determine vector direction.
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// Fly towards the endpoint to prevent flying away,
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// but assume progress=1 either way.
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path_endpoint(start_point, end_point, cur_point, status);
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status->fractional_progress = 1;
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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 / dist_path;
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normal[1] = path_north / dist_path;
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status->fractional_progress = dot / (dist_path * dist_path);
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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 / dist_path;
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status->path_direction[1] = path_east / dist_path;
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}
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/**
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* @brief Compute progress along circular path and deviation from it
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* @param[in] start_point Starting point
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* @param[in] end_point Center 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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static void path_circle(float *start_point, float *end_point, float *cur_point, struct path_status *status, bool clockwise)
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{
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float radius_north, radius_east, diff_north, diff_east;
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float radius, cradius;
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float normal[2];
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float progress;
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float a_diff, a_radius;
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// Radius
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radius_north = end_point[0] - start_point[0];
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radius_east = end_point[1] - start_point[1];
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// Current location relative to center
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diff_north = cur_point[0] - end_point[0];
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diff_east = cur_point[1] - end_point[1];
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radius = sqrtf(powf(radius_north, 2) + powf(radius_east, 2));
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cradius = sqrtf(powf(diff_north, 2) + powf(diff_east, 2));
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if (cradius < 1e-6f) {
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// cradius is zero, just fly somewhere and make sure correction is still a normal
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status->fractional_progress = 1;
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status->error = radius;
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status->correction_direction[0] = 0;
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status->correction_direction[1] = 1;
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status->path_direction[0] = 1;
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status->path_direction[1] = 0;
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return;
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}
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if (clockwise) {
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// Compute the normal to the radius clockwise
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normal[0] = -diff_east / cradius;
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normal[1] = diff_north / cradius;
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} else {
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// Compute the normal to the radius counter clockwise
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normal[0] = diff_east / cradius;
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normal[1] = -diff_north / cradius;
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}
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// normalize progress to 0..1
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a_diff = atan2f(diff_north, diff_east);
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a_radius = atan2f(radius_north, radius_east);
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if (a_diff < 0) {
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a_diff += 2.0f * M_PI_F;
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}
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if (a_radius < 0) {
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a_radius += 2.0f * M_PI_F;
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}
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progress = (a_diff - a_radius + M_PI_F) / (2.0f * M_PI_F);
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if (progress < 0) {
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progress += 1.0f;
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} else if (progress >= 1.0f) {
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progress -= 1.0f;
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}
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if (clockwise) {
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progress = 1 - progress;
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}
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status->fractional_progress = progress;
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// error is current radius minus wanted radius - positive if too close
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status->error = radius - cradius;
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// Compute direction to correct error
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status->correction_direction[0] = (status->error > 0 ? 1 : -1) * diff_north / cradius;
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status->correction_direction[1] = (status->error > 0 ? 1 : -1) * diff_east / cradius;
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// Compute direction to travel
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status->path_direction[0] = normal[0];
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status->path_direction[1] = normal[1];
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status->error = fabs(status->error);
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}
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