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fe6ea7e0e2
Refactored coordinate conversion names in order to be clearer, since two identically named functions-- one in revo, one here-- performed very different maths.
262 lines
8.1 KiB
C++
262 lines
8.1 KiB
C++
/**
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******************************************************************************
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*
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* @file coordinateconversions.cpp
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
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* @brief General conversions with different coordinate systems.
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* - all angles in deg
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* - distances in meters
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* - altitude above WGS-84 elipsoid
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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 "coordinateconversions.h"
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#include <stdint.h>
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#include <QDebug>
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#include <math.h>
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#define RAD2DEG (180.0/M_PI)
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#define DEG2RAD (M_PI/180.0)
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namespace Utils {
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CoordinateConversions::CoordinateConversions()
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{
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}
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/**
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* Get rotation matrix from ECEF to NED for that LLA
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* @param[in] LLA Longitude latitude altitude for this location
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* @param[out] Rne[3][3] Rotation matrix
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*/
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void CoordinateConversions::RneFromLLA(double LLA[3], double Rne[3][3]){
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float sinLat, sinLon, cosLat, cosLon;
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sinLat=(float)sin(DEG2RAD*LLA[0]);
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sinLon=(float)sin(DEG2RAD*LLA[1]);
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cosLat=(float)cos(DEG2RAD*LLA[0]);
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cosLon=(float)cos(DEG2RAD*LLA[1]);
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Rne[0][0] = -sinLat*cosLon; Rne[0][1] = -sinLat*sinLon; Rne[0][2] = cosLat;
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Rne[1][0] = -sinLon; Rne[1][1] = cosLon; Rne[1][2] = 0;
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Rne[2][0] = -cosLat*cosLon; Rne[2][1] = -cosLat*sinLon; Rne[2][2] = -sinLat;
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}
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/**
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* Convert from LLA coordinates to ECEF coordinates
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* @param[in] LLA[3] latitude longitude alititude coordinates in
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* @param[out] ECEF[3] location in ECEF coordinates
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*/
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void CoordinateConversions::LLA2ECEF(double LLA[3], double ECEF[3]){
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const double a = 6378137.0; // Equatorial Radius
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const double e = 8.1819190842622e-2; // Eccentricity
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double sinLat, sinLon, cosLat, cosLon;
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double N;
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sinLat=sin(DEG2RAD*LLA[0]);
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sinLon=sin(DEG2RAD*LLA[1]);
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cosLat=cos(DEG2RAD*LLA[0]);
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cosLon=cos(DEG2RAD*LLA[1]);
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N = a / sqrt(1.0 - e*e*sinLat*sinLat); //prime vertical radius of curvature
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ECEF[0] = (N+LLA[2])*cosLat*cosLon;
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ECEF[1] = (N+LLA[2])*cosLat*sinLon;
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ECEF[2] = ((1-e*e)*N + LLA[2]) * sinLat;
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}
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/**
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* Convert from ECEF coordinates to LLA coordinates
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* @param[in] ECEF[3] location in ECEF coordinates
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* @param[out] LLA[3] latitude longitude alititude coordinates
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*/
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int CoordinateConversions::ECEF2LLA(double ECEF[3], double LLA[3])
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{
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const double a = 6378137.0; // Equatorial Radius
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const double e = 8.1819190842622e-2; // Eccentricity
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double x=ECEF[0], y=ECEF[1], z=ECEF[2];
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double Lat, N, NplusH, delta, esLat;
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uint16_t iter;
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LLA[1] = RAD2DEG*atan2(y,x);
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N = a;
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NplusH = N;
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delta = 1;
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Lat = 1;
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iter=0;
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while (((delta > 1.0e-14)||(delta < -1.0e-14)) && (iter < 100))
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{
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delta = Lat - atan(z / (sqrt(x*x + y*y)*(1-(N*e*e/NplusH))));
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Lat = Lat-delta;
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esLat = e*sin(Lat);
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N = a / sqrt(1 - esLat*esLat);
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NplusH = sqrt(x*x + y*y)/cos(Lat);
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iter += 1;
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}
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LLA[0] = RAD2DEG*Lat;
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LLA[2] = NplusH - N;
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if (iter==500) return (0);
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else return (1);
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}
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/**
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* Get the current location in Longitude, Latitude Altitude (above WSG-84 ellipsoid)
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* @param[in] BaseECEF the ECEF of the home location (in m)
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* @param[in] NED the offset from the home location (in m)
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* @param[out] position three element double for position in decimal degrees and altitude in meters
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* @returns
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* @arg 0 success
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* @arg -1 for failure
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*/
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int CoordinateConversions::NED2LLA_HomeECEF(double BaseECEFm[3], double NED[3], double position[3])
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{
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int i;
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// stored value is in cm, convert to m
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double BaseLLA[3];
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double ECEF[3];
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double Rne [3][3];
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// Get LLA address to compute conversion matrix
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ECEF2LLA(BaseECEFm, BaseLLA);
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RneFromLLA(BaseLLA, Rne);
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/* P = ECEF + Rne' * NED */
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for(i = 0; i < 3; i++)
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ECEF[i] = BaseECEFm[i] + Rne[0][i]*NED[0] + Rne[1][i]*NED[1] + Rne[2][i]*NED[2];
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ECEF2LLA(ECEF,position);
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return 0;
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}
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/**
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* Get the current location in Longitude, Latitude, Altitude (above WSG-84 ellipsoid)
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* @param[in] homeLLA the latitude, longitude, and altitude of the home location (in [m])
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* @param[in] NED the offset from the home location (in [m])
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* @param[out] position three element double for position in decimal degrees and altitude in meters
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* @returns
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* @arg 0 success
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* @arg -1 for failure
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*/
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int CoordinateConversions::NED2LLA_HomeLLA(double homeLLA[3], double NED[3], double position[3])
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{
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double T[3];
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T[0] = homeLLA[2]+6.378137E6f * M_PI / 180.0;
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T[1] = cosf(homeLLA[0] * M_PI / 180.0)*(homeLLA[2]+6.378137E6f) * M_PI / 180.0;
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T[2] = -1.0f;
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position[0] = homeLLA[0] + NED[0] / T[0];
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position[1] = homeLLA[1] + NED[1] / T[1];
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position[2] = homeLLA[2] + NED[2] / T[2];
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return 0;
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}
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void CoordinateConversions::LLA2Base(double LLA[3], double BaseECEF[3], float Rne[3][3], float NED[3])
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{
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double ECEF[3];
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float diff[3];
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LLA2ECEF(LLA, ECEF);
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diff[0] = (float)(ECEF[0] - BaseECEF[0]);
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diff[1] = (float)(ECEF[1] - BaseECEF[1]);
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diff[2] = (float)(ECEF[2] - BaseECEF[2]);
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NED[0] = Rne[0][0] * diff[0] + Rne[0][1] * diff[1] + Rne[0][2] * diff[2];
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NED[1] = Rne[1][0] * diff[0] + Rne[1][1] * diff[1] + Rne[1][2] * diff[2];
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NED[2] = Rne[2][0] * diff[0] + Rne[2][1] * diff[1] + Rne[2][2] * diff[2];
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}
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// ****** find roll, pitch, yaw from quaternion ********
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void CoordinateConversions::Quaternion2RPY(const float q[4], float rpy[3])
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{
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float R13, R11, R12, R23, R33;
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float q0s = q[0] * q[0];
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float q1s = q[1] * q[1];
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float q2s = q[2] * q[2];
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float q3s = q[3] * q[3];
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R13 = 2 * (q[1] * q[3] - q[0] * q[2]);
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R11 = q0s + q1s - q2s - q3s;
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R12 = 2 * (q[1] * q[2] + q[0] * q[3]);
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R23 = 2 * (q[2] * q[3] + q[0] * q[1]);
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R33 = q0s - q1s - q2s + q3s;
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rpy[1] = RAD2DEG * asinf(-R13); // pitch always between -pi/2 to pi/2
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rpy[2] = RAD2DEG * atan2f(R12, R11);
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rpy[0] = RAD2DEG * atan2f(R23, R33);
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//TODO: consider the cases where |R13| ~= 1, |pitch| ~= pi/2
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}
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// ****** find quaternion from roll, pitch, yaw ********
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void CoordinateConversions::RPY2Quaternion(const float rpy[3], float q[4])
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{
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float phi, theta, psi;
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float cphi, sphi, ctheta, stheta, cpsi, spsi;
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phi = DEG2RAD * rpy[0] / 2;
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theta = DEG2RAD * rpy[1] / 2;
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psi = DEG2RAD * rpy[2] / 2;
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cphi = cosf(phi);
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sphi = sinf(phi);
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ctheta = cosf(theta);
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stheta = sinf(theta);
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cpsi = cosf(psi);
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spsi = sinf(psi);
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q[0] = cphi * ctheta * cpsi + sphi * stheta * spsi;
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q[1] = sphi * ctheta * cpsi - cphi * stheta * spsi;
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q[2] = cphi * stheta * cpsi + sphi * ctheta * spsi;
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q[3] = cphi * ctheta * spsi - sphi * stheta * cpsi;
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if (q[0] < 0) { // q0 always positive for uniqueness
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q[0] = -q[0];
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q[1] = -q[1];
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q[2] = -q[2];
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q[3] = -q[3];
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}
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}
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//** Find Rbe, that rotates a vector from earth fixed to body frame, from quaternion **
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void CoordinateConversions::Quaternion2R(const float q[4], float Rbe[3][3])
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{
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float q0s = q[0] * q[0], q1s = q[1] * q[1], q2s = q[2] * q[2], q3s = q[3] * q[3];
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Rbe[0][0] = q0s + q1s - q2s - q3s;
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Rbe[0][1] = 2 * (q[1] * q[2] + q[0] * q[3]);
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Rbe[0][2] = 2 * (q[1] * q[3] - q[0] * q[2]);
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Rbe[1][0] = 2 * (q[1] * q[2] - q[0] * q[3]);
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Rbe[1][1] = q0s - q1s + q2s - q3s;
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Rbe[1][2] = 2 * (q[2] * q[3] + q[0] * q[1]);
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Rbe[2][0] = 2 * (q[1] * q[3] + q[0] * q[2]);
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Rbe[2][1] = 2 * (q[2] * q[3] - q[0] * q[1]);
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Rbe[2][2] = q0s - q1s - q2s + q3s;
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}
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}
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