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/****************************************************************************
*
* Copyright (C) 2014 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file gnss.cpp
*
* @author Pavel Kirienko <pavel.kirienko@gmail.com>
* @author Andrew Chambers <achamber@gmail.com>
*
*/
#include "gnss.hpp"
#include <systemlib/err.h>
#include <mathlib/mathlib.h>
#define MM_PER_CM 10 // Millimeters per centimeter
const char *const UavcanGnssBridge::NAME = "gnss";
UavcanGnssBridge::UavcanGnssBridge(uavcan::INode &node) :
_node(node),
_sub_fix(node),
_report_pub(-1)
{
}
int UavcanGnssBridge::init()
{
int res = _sub_fix.start(FixCbBinder(this, &UavcanGnssBridge::gnss_fix_sub_cb));
if (res < 0)
{
warnx("GNSS fix sub failed %i", res);
return res;
}
return res;
}
unsigned UavcanGnssBridge::get_num_redundant_channels() const
{
return (_receiver_node_id < 0) ? 0 : 1;
}
void UavcanGnssBridge::print_status() const
{
printf("RX errors: %d, receiver node id: ", _sub_fix.getFailureCount());
if (_receiver_node_id < 0) {
printf("N/A\n");
} else {
printf("%d\n", _receiver_node_id);
}
}
void UavcanGnssBridge::gnss_fix_sub_cb(const uavcan::ReceivedDataStructure<uavcan::equipment::gnss::Fix> &msg)
{
// This bridge does not support redundant GNSS receivers yet.
if (_receiver_node_id < 0) {
_receiver_node_id = msg.getSrcNodeID().get();
warnx("GNSS receiver node ID: %d", _receiver_node_id);
} else {
if (_receiver_node_id != msg.getSrcNodeID().get()) {
return; // This GNSS receiver is the redundant one, ignore it.
}
}
auto report = ::vehicle_gps_position_s();
report.timestamp_position = hrt_absolute_time();
report.lat = msg.lat_1e7;
report.lon = msg.lon_1e7;
report.alt = msg.alt_1e2 * MM_PER_CM; // Convert from centimeter (1e2) to millimeters (1e3)
report.timestamp_variance = report.timestamp_position;
// Check if the msg contains valid covariance information
const bool valid_position_covariance = !msg.position_covariance.empty();
const bool valid_velocity_covariance = !msg.velocity_covariance.empty();
if (valid_position_covariance) {
float pos_cov[9];
msg.position_covariance.unpackSquareMatrix(pos_cov);
// Horizontal position uncertainty
const float horizontal_pos_variance = math::max(pos_cov[0], pos_cov[4]);
report.eph = (horizontal_pos_variance > 0) ? sqrtf(horizontal_pos_variance) : -1.0F;
// Vertical position uncertainty
report.epv = (pos_cov[8] > 0) ? sqrtf(pos_cov[8]) : -1.0F;
} else {
report.eph = -1.0F;
report.epv = -1.0F;
}
if (valid_velocity_covariance) {
float vel_cov[9];
msg.velocity_covariance.unpackSquareMatrix(vel_cov);
report.s_variance_m_s = math::max(math::max(vel_cov[0], vel_cov[4]), vel_cov[8]);
/* There is a nonlinear relationship between the velocity vector and the heading.
* Use Jacobian to transform velocity covariance to heading covariance
*
* Nonlinear equation:
* heading = atan2(vel_e_m_s, vel_n_m_s)
* For math, see http://en.wikipedia.org/wiki/Atan2#Derivative
*
* To calculate the variance of heading from the variance of velocity,
* cov(heading) = J(velocity)*cov(velocity)*J(velocity)^T
*/
float vel_n = msg.ned_velocity[0];
float vel_e = msg.ned_velocity[1];
float vel_n_sq = vel_n * vel_n;
float vel_e_sq = vel_e * vel_e;
report.c_variance_rad =
(vel_e_sq * vel_cov[0] +
-2 * vel_n * vel_e * vel_cov[1] + // Covariance matrix is symmetric
vel_n_sq* vel_cov[4]) / ((vel_n_sq + vel_e_sq) * (vel_n_sq + vel_e_sq));
} else {
report.s_variance_m_s = -1.0F;
report.c_variance_rad = -1.0F;
}
report.fix_type = msg.status;
report.timestamp_velocity = report.timestamp_position;
report.vel_n_m_s = msg.ned_velocity[0];
report.vel_e_m_s = msg.ned_velocity[1];
report.vel_d_m_s = msg.ned_velocity[2];
report.vel_m_s = sqrtf(report.vel_n_m_s * report.vel_n_m_s + report.vel_e_m_s * report.vel_e_m_s + report.vel_d_m_s * report.vel_d_m_s);
report.cog_rad = atan2f(report.vel_e_m_s, report.vel_n_m_s);
report.vel_ned_valid = true;
report.timestamp_time = report.timestamp_position;
report.time_gps_usec = uavcan::UtcTime(msg.gnss_timestamp).toUSec(); // Convert to microseconds
report.satellites_used = msg.sats_used;
if (_report_pub > 0) {
orb_publish(ORB_ID(vehicle_gps_position), _report_pub, &report);
} else {
_report_pub = orb_advertise(ORB_ID(vehicle_gps_position), &report);
}
}
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