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Diffstat (limited to 'src/modules/uavcan/gnss_receiver.cpp')
| -rw-r--r-- | src/modules/uavcan/gnss_receiver.cpp | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/src/modules/uavcan/gnss_receiver.cpp b/src/modules/uavcan/gnss_receiver.cpp new file mode 100644 index 000000000..ba1fe5e49 --- /dev/null +++ b/src/modules/uavcan/gnss_receiver.cpp @@ -0,0 +1,153 @@ +/**************************************************************************** + * + * 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> +#include <mathlib/mathlib.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; + + + // 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); + } + +} |