ardupilot/libraries/AP_AHRS/AP_AHRS_NavEKF.cpp

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/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* NavEKF based AHRS (Attitude Heading Reference System) interface for
* ArduPilot
*
*/
#include <AP_HAL/AP_HAL.h>
#include "AP_AHRS.h"
#include <AP_Vehicle/AP_Vehicle.h>
#if AP_AHRS_NAVEKF_AVAILABLE
extern const AP_HAL::HAL& hal;
// return the smoothed gyro vector corrected for drift
const Vector3f &AP_AHRS_NavEKF::get_gyro(void) const
{
if (!using_EKF()) {
return AP_AHRS_DCM::get_gyro();
}
return _gyro_estimate;
}
const Matrix3f &AP_AHRS_NavEKF::get_dcm_matrix(void) const
{
if (!using_EKF()) {
return AP_AHRS_DCM::get_dcm_matrix();
}
return _dcm_matrix;
}
const Vector3f &AP_AHRS_NavEKF::get_gyro_drift(void) const
{
if (!using_EKF()) {
return AP_AHRS_DCM::get_gyro_drift();
}
return _gyro_bias;
}
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// reset the current gyro drift estimate
// should be called if gyro offsets are recalculated
void AP_AHRS_NavEKF::reset_gyro_drift(void)
{
// update DCM
AP_AHRS_DCM::reset_gyro_drift();
// reset the EKF gyro bias states
EKF.resetGyroBias();
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}
void AP_AHRS_NavEKF::update(void)
{
// we need to restore the old DCM attitude values as these are
// used internally in DCM to calculate error values for gyro drift
// correction
roll = _dcm_attitude.x;
pitch = _dcm_attitude.y;
yaw = _dcm_attitude.z;
update_cd_values();
AP_AHRS_DCM::update();
// keep DCM attitude available for get_secondary_attitude()
_dcm_attitude(roll, pitch, yaw);
if (!ekf_started) {
// wait 1 second for DCM to output a valid tilt error estimate
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if (start_time_ms == 0) {
start_time_ms = hal.scheduler->millis();
}
if (hal.scheduler->millis() - start_time_ms > startup_delay_ms) {
ekf_started = EKF.InitialiseFilterDynamic();
}
}
if (ekf_started) {
EKF.UpdateFilter();
EKF.getRotationBodyToNED(_dcm_matrix);
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if (using_EKF()) {
Vector3f eulers;
EKF.getEulerAngles(eulers);
roll = eulers.x;
pitch = eulers.y;
yaw = eulers.z;
update_cd_values();
update_trig();
// keep _gyro_bias for get_gyro_drift()
EKF.getGyroBias(_gyro_bias);
_gyro_bias = -_gyro_bias;
// calculate corrected gryo estimate for get_gyro()
_gyro_estimate.zero();
uint8_t healthy_count = 0;
for (uint8_t i=0; i<_ins.get_gyro_count(); i++) {
if (_ins.get_gyro_health(i) && healthy_count < 2) {
_gyro_estimate += _ins.get_gyro(i);
healthy_count++;
}
}
if (healthy_count > 1) {
_gyro_estimate /= healthy_count;
}
_gyro_estimate += _gyro_bias;
float abias1, abias2;
EKF.getAccelZBias(abias1, abias2);
// update _accel_ef_ekf
for (uint8_t i=0; i<_ins.get_accel_count(); i++) {
Vector3f accel = _ins.get_accel(i);
if (i==0) {
accel.z -= abias1;
} else if (i==1) {
accel.z -= abias2;
}
if (_ins.get_accel_health(i)) {
_accel_ef_ekf[i] = _dcm_matrix * accel;
}
}
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if(_ins.use_accel(0) && _ins.use_accel(1)) {
float IMU1_weighting;
EKF.getIMU1Weighting(IMU1_weighting);
_accel_ef_ekf_blended = _accel_ef_ekf[0] * IMU1_weighting + _accel_ef_ekf[1] * (1.0f-IMU1_weighting);
} else {
_accel_ef_ekf_blended = _accel_ef_ekf[_ins.get_primary_accel()];
}
}
}
}
// accelerometer values in the earth frame in m/s/s
const Vector3f &AP_AHRS_NavEKF::get_accel_ef(uint8_t i) const
{
if(!using_EKF()) {
return AP_AHRS_DCM::get_accel_ef(i);
}
return _accel_ef_ekf[i];
}
// blended accelerometer values in the earth frame in m/s/s
const Vector3f &AP_AHRS_NavEKF::get_accel_ef_blended(void) const
{
if(!using_EKF()) {
return AP_AHRS_DCM::get_accel_ef_blended();
}
return _accel_ef_ekf_blended;
}
void AP_AHRS_NavEKF::reset(bool recover_eulers)
{
AP_AHRS_DCM::reset(recover_eulers);
if (ekf_started) {
ekf_started = EKF.InitialiseFilterBootstrap();
}
}
// reset the current attitude, used on new IMU calibration
void AP_AHRS_NavEKF::reset_attitude(const float &_roll, const float &_pitch, const float &_yaw)
{
AP_AHRS_DCM::reset_attitude(_roll, _pitch, _yaw);
if (ekf_started) {
ekf_started = EKF.InitialiseFilterBootstrap();
}
}
// dead-reckoning support
bool AP_AHRS_NavEKF::get_position(struct Location &loc) const
{
Vector3f ned_pos;
if (using_EKF() && EKF.getLLH(loc) && EKF.getPosNED(ned_pos)) {
// fixup altitude using relative position from AHRS home, not
// EKF origin
loc.alt = get_home().alt - ned_pos.z*100;
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return true;
}
return AP_AHRS_DCM::get_position(loc);
}
// status reporting of estimated errors
float AP_AHRS_NavEKF::get_error_rp(void) const
{
return AP_AHRS_DCM::get_error_rp();
}
float AP_AHRS_NavEKF::get_error_yaw(void) const
{
return AP_AHRS_DCM::get_error_yaw();
}
// return a wind estimation vector, in m/s
Vector3f AP_AHRS_NavEKF::wind_estimate(void)
{
if (!using_EKF()) {
// EKF does not estimate wind speed when there is no airspeed
// sensor active
return AP_AHRS_DCM::wind_estimate();
}
Vector3f wind;
EKF.getWind(wind);
return wind;
}
// return an airspeed estimate if available. return true
// if we have an estimate
bool AP_AHRS_NavEKF::airspeed_estimate(float *airspeed_ret) const
{
return AP_AHRS_DCM::airspeed_estimate(airspeed_ret);
}
// true if compass is being used
bool AP_AHRS_NavEKF::use_compass(void)
{
if (using_EKF()) {
return EKF.use_compass();
}
return AP_AHRS_DCM::use_compass();
}
// return secondary attitude solution if available, as eulers in radians
bool AP_AHRS_NavEKF::get_secondary_attitude(Vector3f &eulers)
{
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if (using_EKF()) {
// return DCM attitude
eulers = _dcm_attitude;
return true;
}
if (ekf_started) {
// EKF is secondary
EKF.getEulerAngles(eulers);
return true;
}
// no secondary available
return false;
}
// return secondary position solution if available
bool AP_AHRS_NavEKF::get_secondary_position(struct Location &loc)
{
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if (using_EKF()) {
// return DCM position
AP_AHRS_DCM::get_position(loc);
return true;
}
if (ekf_started) {
// EKF is secondary
EKF.getLLH(loc);
return true;
}
// no secondary available
return false;
}
// EKF has a better ground speed vector estimate
Vector2f AP_AHRS_NavEKF::groundspeed_vector(void)
{
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if (!using_EKF()) {
return AP_AHRS_DCM::groundspeed_vector();
}
Vector3f vec;
EKF.getVelNED(vec);
return Vector2f(vec.x, vec.y);
}
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void AP_AHRS_NavEKF::set_home(const Location &loc)
{
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AP_AHRS_DCM::set_home(loc);
}
// return true if inertial navigation is active
bool AP_AHRS_NavEKF::have_inertial_nav(void) const
{
return using_EKF();
}
// return a ground velocity in meters/second, North/East/Down
// order. Must only be called if have_inertial_nav() is true
bool AP_AHRS_NavEKF::get_velocity_NED(Vector3f &vec) const
{
if (using_EKF()) {
EKF.getVelNED(vec);
return true;
}
return false;
}
// return a relative ground position in meters/second, North/East/Down
// order. Must only be called if have_inertial_nav() is true
bool AP_AHRS_NavEKF::get_relative_position_NED(Vector3f &vec) const
{
if (using_EKF()) {
return EKF.getPosNED(vec);
}
return false;
}
bool AP_AHRS_NavEKF::using_EKF(void) const
{
uint8_t ekf_faults;
EKF.getFilterFaults(ekf_faults);
// If EKF is started we switch away if it reports unhealthy. This could be due to bad
// sensor data. If EKF reversion is inhibited, we only switch across if the EKF encounters
// an internal processing error, but not for bad sensor data.
bool ret = ekf_started && ((_ekf_use == EKF_USE_WITH_FALLBACK && EKF.healthy()) || (_ekf_use == EKF_USE_WITHOUT_FALLBACK && ekf_faults == 0));
if (!ret) {
return false;
}
if (_vehicle_class == AHRS_VEHICLE_FIXED_WING ||
_vehicle_class == AHRS_VEHICLE_GROUND) {
nav_filter_status filt_state;
EKF.getFilterStatus(filt_state);
if (hal.util->get_soft_armed() && !filt_state.flags.using_gps && _gps.status() >= AP_GPS::GPS_OK_FIX_3D) {
// if the EKF is not fusing GPS and we have a 3D lock, then
// plane and rover would prefer to use the GPS position from
// DCM. This is a safety net while some issues with the EKF
// get sorted out
return false;
}
if (hal.util->get_soft_armed() && filt_state.flags.const_pos_mode) {
return false;
}
if (!filt_state.flags.attitude ||
!filt_state.flags.horiz_vel ||
!filt_state.flags.vert_vel ||
!filt_state.flags.horiz_pos_abs ||
!filt_state.flags.vert_pos) {
return false;
}
}
return ret;
}
/*
check if the AHRS subsystem is healthy
*/
bool AP_AHRS_NavEKF::healthy(void) const
{
// If EKF is started we switch away if it reports unhealthy. This could be due to bad
// sensor data. If EKF reversion is inhibited, we only switch across if the EKF encounters
// an internal processing error, but not for bad sensor data.
if (_ekf_use != EKF_DO_NOT_USE) {
bool ret = ekf_started && EKF.healthy();
if (!ret) {
return false;
}
if ((_vehicle_class == AHRS_VEHICLE_FIXED_WING ||
_vehicle_class == AHRS_VEHICLE_GROUND) &&
!using_EKF()) {
// on fixed wing we want to be using EKF to be considered
// healthy if EKF is enabled
return false;
}
return true;
}
return AP_AHRS_DCM::healthy();
}
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void AP_AHRS_NavEKF::set_ekf_use(bool setting)
{
#if !AHRS_EKF_USE_ALWAYS
_ekf_use.set(setting);
#endif
}
// true if the AHRS has completed initialisation
bool AP_AHRS_NavEKF::initialised(void) const
{
// initialisation complete 10sec after ekf has started
return (ekf_started && (hal.scheduler->millis() - start_time_ms > AP_AHRS_NAVEKF_SETTLE_TIME_MS));
};
// write optical flow data to EKF
void AP_AHRS_NavEKF::writeOptFlowMeas(uint8_t &rawFlowQuality, Vector2f &rawFlowRates, Vector2f &rawGyroRates, uint32_t &msecFlowMeas)
{
EKF.writeOptFlowMeas(rawFlowQuality, rawFlowRates, rawGyroRates, msecFlowMeas);
}
// inhibit GPS useage
uint8_t AP_AHRS_NavEKF::setInhibitGPS(void)
{
return EKF.setInhibitGPS();
}
// get speed limit
void AP_AHRS_NavEKF::getEkfControlLimits(float &ekfGndSpdLimit, float &ekfNavVelGainScaler)
{
EKF.getEkfControlLimits(ekfGndSpdLimit,ekfNavVelGainScaler);
}
// get compass offset estimates
// true if offsets are valid
bool AP_AHRS_NavEKF::getMagOffsets(Vector3f &magOffsets)
{
bool status = EKF.getMagOffsets(magOffsets);
return status;
}
#endif // AP_AHRS_NAVEKF_AVAILABLE