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WIP: Correct velocity frame for fake_gps. #1722

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WIP: Correct velocity frame for fake_gps. #1722

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7ae7cf5
Correct velocity frame for fake_gps.
jgoppert Mar 8, 2022
4c47d53
Improve dcm initialization readability.
jgoppert Mar 8, 2022
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37 changes: 22 additions & 15 deletions mavros_extras/src/plugins/fake_gps.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -227,7 +227,14 @@ class FakeGPSPlugin : public plugin::PluginBase,
ROS_INFO_STREAM("FGPS: Caught exception: " << e.what() << std::endl);
}

Eigen::Vector3d vel = (old_ecef - current_ecef) / (stamp.toSec() - old_stamp); // [m/s]
double lat = geodetic.x();
double lon = geodetic.y();
Eigen::Matrix<double, 3, 3> dcm_ned_ecef;
dcm_ned_ecef << -sin(lat)*cos(lon), -sin(lat)*sin(lon), cos(lat),
-sin(lon), cos(lon), 0,
-cos(lat)*cos(lon), -cos(lat)*sin(lon), -sin(lat);
Eigen::Vector3d vel_ecef = (old_ecef - current_ecef) / (stamp.toSec() - old_stamp); // [m/s]
Eigen::Vector3d vel_ned = dcm_ned_ecef*vel_ecef;

// store old values
old_stamp = stamp.toSec();
Expand All @@ -242,18 +249,18 @@ class FakeGPSPlugin : public plugin::PluginBase,
*/
mavlink::common::msg::HIL_GPS hil_gps {};

vel *= 1e2; // [cm/s]
vel_ned *= 1e2; // [cm/s]

// compute course over ground
double cog;
if (vel.x() == 0 && vel.y() == 0) {
if (vel_ned.x() == 0 && vel_ned.y() == 0) {
cog = 0;
}
else if (vel.x() >= 0 && vel.y() < 0) {
cog = M_PI * 5 / 2 - atan2(vel.x(), vel.y());
else if (vel_ned.x() >= 0 && vel_ned.y() < 0) {
cog = M_PI * 5 / 2 - atan2(vel_ned.x(), vel_ned.y());
}
else {
cog = M_PI / 2 - atan2(vel.x(), vel.y());
cog = M_PI / 2 - atan2(vel_ned.x(), vel_ned.y());
}

// Fill in and send message
Expand All @@ -262,10 +269,10 @@ class FakeGPSPlugin : public plugin::PluginBase,
hil_gps.lon = geodetic.y() * 1e7; // [degrees * 1e7]
hil_gps.alt = (geodetic.z() + GeographicLib::Geoid::ELLIPSOIDTOGEOID *
(*m_uas->egm96_5)(geodetic.x(), geodetic.y())) * 1e3; // [meters * 1e3]
hil_gps.vel = vel.block<2, 1>(0, 0).norm(); // [cm/s]
hil_gps.vn = vel.x(); // [cm/s]
hil_gps.ve = vel.y(); // [cm/s]
hil_gps.vd = vel.z(); // [cm/s]
hil_gps.vel = vel_ned.block<2, 1>(0, 0).norm(); // [cm/s]
hil_gps.vn = vel_ned.x(); // [cm/s]
hil_gps.ve = vel_ned.y(); // [cm/s]
hil_gps.vd = vel_ned.z(); // [cm/s]
hil_gps.cog = cog * 1e2; // [degrees * 1e2]
hil_gps.eph = eph * 1e2; // [cm]
hil_gps.epv = epv * 1e2; // [cm]
Expand All @@ -291,9 +298,9 @@ class FakeGPSPlugin : public plugin::PluginBase,
gps_input.ignore_flags |= utils::enum_value(GPS_INPUT_IGNORE_FLAGS::FLAG_HDOP);
if (epv == 0.0f)
gps_input.ignore_flags |= utils::enum_value(GPS_INPUT_IGNORE_FLAGS::FLAG_VDOP);
if (fabs(vel.x()) <= 0.01f && fabs(vel.y()) <= 0.01f)
if (fabs(vel_ned.x()) <= 0.01f && fabs(vel_ned.y()) <= 0.01f)
gps_input.ignore_flags |= utils::enum_value(GPS_INPUT_IGNORE_FLAGS::FLAG_VEL_HORIZ);
if (fabs(vel.z()) <= 0.01f)
if (fabs(vel_ned.z()) <= 0.01f)
gps_input.ignore_flags |= utils::enum_value(GPS_INPUT_IGNORE_FLAGS::FLAG_VEL_VERT);
int64_t tdiff = (gps_input.time_usec / 1000) - UNIX_OFFSET_MSEC;
gps_input.time_week = tdiff / MSEC_PER_WEEK;
Expand All @@ -305,9 +312,9 @@ class FakeGPSPlugin : public plugin::PluginBase,
gps_input.lon = geodetic.y() * 1e7; // [degrees * 1e7]
gps_input.alt = (geodetic.z() + GeographicLib::Geoid::ELLIPSOIDTOGEOID *
(*m_uas->egm96_5)(geodetic.x(), geodetic.y())); // [meters]
gps_input.vn = vel.x(); // [m/s]
gps_input.ve = vel.y(); // [m/s]
gps_input.vd = vel.z(); // [m/s]
gps_input.vn = vel_ned.x(); // [m/s]
gps_input.ve = vel_ned.y(); // [m/s]
gps_input.vd = vel_ned.z(); // [m/s]
gps_input.hdop = eph; // [m]
gps_input.vdop = epv; // [m]
gps_input.fix_type = utils::enum_value(fix_type);;
Expand Down