航行时，计算地球上2个位置的距离，方位角度程序

最新推荐文章于 2023-08-13 21:06:08 发布

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最新推荐文章于 2023-08-13 21:06:08 发布 · 2.1k 阅读

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本文探讨如何在航行过程中，利用编程技术计算地球上两个位置之间的距离和方位角度，以Pixhawk中location.cpp为例进行详细讲解。

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参考Pixhawk中location.cpp

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
 * location.cpp
 * Copyright (C) Andrew Tridgell 2011
 *
 * This file is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This file is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *  this module deals with calculations involving struct Location
 */
#include <AP_HAL/AP_HAL.h>
#include <stdlib.h>
#include "AP_Math.h"
#include "location.h"

// scaling factor from 1e-7 degrees to meters at equater
// == 1.0e-7 * DEG_TO_RAD * RADIUS_OF_EARTH
#define LOCATION_SCALING_FACTOR 0.011131884502145034f
// inverse of LOCATION_SCALING_FACTOR
#define LOCATION_SCALING_FACTOR_INV 89.83204953368922f

float longitude_scale(const struct Location &loc)
{
#if HAL_CPU_CLASS < HAL_CPU_CLASS_150
    static int32_t last_lat;
    static float scale = 1.0;
    // don't optimise on faster CPUs. It causes some minor errors on Replay
    if (labs(last_lat - loc.lat) < 100000) {
        // we are within 0.01 degrees (about 1km) of the
        // same latitude. We can avoid the cos() and return
        // the same scale factor.
        return scale;
    }
    scale = cosf(loc.lat * 1.0e-7f * DEG_TO_RAD);
    scale = constrain_float(scale, 0.01f, 1.0f);
    last_lat = loc.lat;
    return scale;
#else
    float scale = cosf(loc.lat * 1.0e-7f * DEG_TO_RAD);
    return constrain_float(scale, 0.01f, 1.0f);
#endif
}



// return distance in meters between two locations
float get_distance(const struct Location &loc1, const struct Location &loc2)
{
    float dlat              = (float)(loc2.lat - loc1.lat);
    float dlong             = ((float)(loc2.lng - loc1.lng)) * longitude_scale(loc2);
    return pythagorous2(dlat, dlong) * LOCATION_SCALING_FACTOR;
}

// return distance in centimeters to between two locations
uint32_t get_d