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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_receiver.cpp
*
* @author Pavel Kirienko <pavel.kirienko@gmail.com>
* @author Andrew Chambers <achamber@gmail.com>
*
*/
#include "gnss_receiver.hpp"
#include <systemlib/err.h>
#define MM_PER_CM 10 // Millimeters per centimeter
UavcanGnssReceiver::UavcanGnssReceiver(uavcan::INode &node) :
_node(node),
_uavcan_sub_status(node),
_report_pub(-1)
{
}
int UavcanGnssReceiver::init()
{
int res = -1;
// GNSS fix subscription
res = _uavcan_sub_status.start(FixCbBinder(this, &UavcanGnssReceiver::gnss_fix_sub_cb));
if (res < 0)
{
warnx("GNSS fix sub failed %i", res);
return res;
}
// Clear the uORB GPS report
memset(&_report, 0, sizeof(_report));
return res;
}
void UavcanGnssReceiver::gnss_fix_sub_cb(const uavcan::ReceivedDataStructure<uavcan::equipment::gnss::Fix> &msg)
{
_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;
_report.s_variance_m_s = msg.velocity_covariance[0] + msg.velocity_covariance[4] + msg.velocity_covariance[8];
_report.p_variance_m = msg.position_covariance[0] + msg.position_covariance[4];
/* Use Jacobian to transform velocity covariance to heading covariance
* 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,
* var(heading) = J(velocity)*var(velocity)*J(velocity)^T
*/
_report.c_variance_rad =
msg.ned_velocity[1] * msg.ned_velocity[1] * msg.velocity_covariance[0] +
-2*msg.ned_velocity[1] * msg.ned_velocity[0] * msg.velocity_covariance[1] +
msg.ned_velocity[0] * msg.ned_velocity[0] * msg.velocity_covariance[4];
_report.fix_type = msg.status;
_report.eph_m = sqrtf(_report.p_variance_m);
_report.epv_m = sqrtf(msg.position_covariance[8]);
_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 = msg.timestamp.husec * msg.timestamp.USEC_PER_LSB; // Convert to microseconds
_report.timestamp_satellites = _report.timestamp_position;
_report.satellites_visible = msg.sats_used;
_report.satellite_info_available = 0; // Set to 0 for no info available
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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