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2bafe9df08
This fixes the cases where the yaw message from the GNSS receiver would take more time than the vel/pos. The estimator should wait and not immediately fall back to an other aiding source after 5sec. If it never comes, it will never fall back, but this is ok since the user wants to fly with GPS aiding an not with something else.
1343 lines
53 KiB
C++
1343 lines
53 KiB
C++
/****************************************************************************
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*
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* Copyright (c) 2015-2020 Estimation and Control Library (ECL). All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name ECL nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/**
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* @file control.cpp
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* Control functions for ekf attitude and position estimator.
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*
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* @author Paul Riseborough <p_riseborough@live.com.au>
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*
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*/
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#include "../ecl.h"
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#include "ekf.h"
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#include <mathlib/mathlib.h>
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void Ekf::controlFusionModes()
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{
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// Store the status to enable change detection
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_control_status_prev.value = _control_status.value;
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// monitor the tilt alignment
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if (!_control_status.flags.tilt_align) {
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// whilst we are aligning the tilt, monitor the variances
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const Vector3f angle_err_var_vec = calcRotVecVariances();
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// Once the tilt variances have reduced to equivalent of 3deg uncertainty, re-set the yaw and magnetic field states
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// and declare the tilt alignment complete
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if ((angle_err_var_vec(0) + angle_err_var_vec(1)) < sq(math::radians(3.0f))) {
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_control_status.flags.tilt_align = true;
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_control_status.flags.yaw_align = resetMagHeading(_mag_lpf.getState()); // TODO: is this needed?
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// send alignment status message to the console
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const char* height_source = nullptr;
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if (_control_status.flags.baro_hgt) {
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height_source = "baro";
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} else if (_control_status.flags.ev_hgt) {
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height_source = "ev";
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} else if (_control_status.flags.gps_hgt) {
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height_source = "gps";
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} else if (_control_status.flags.rng_hgt) {
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height_source = "rng";
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} else {
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height_source = "unknown";
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}
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if(height_source){
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ECL_INFO("%llu: EKF aligned, (%s hgt, IMU buf: %i, OBS buf: %i)",
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(unsigned long long)_imu_sample_delayed.time_us, height_source, (int)_imu_buffer_length, (int)_obs_buffer_length);
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}
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}
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}
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// check for intermittent data (before pop_first_older_than)
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const baroSample &baro_init = _baro_buffer.get_newest();
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_baro_hgt_faulty = !isRecent(baro_init.time_us, 2 * BARO_MAX_INTERVAL);
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const gpsSample &gps_init = _gps_buffer.get_newest();
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_gps_hgt_intermittent = !isRecent(gps_init.time_us, 2 * GPS_MAX_INTERVAL);
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// check for arrival of new sensor data at the fusion time horizon
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_time_prev_gps_us = _gps_sample_delayed.time_us;
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_gps_data_ready = _gps_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_gps_sample_delayed);
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_mag_data_ready = _mag_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_mag_sample_delayed);
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if (_mag_data_ready) {
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// if enabled, use knowledge of theoretical magnetic field vector to calculate a synthetic magnetomter Z component value.
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// this is useful if there is a lot of interference on the sensor measurement.
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if (_params.synthesize_mag_z && (_params.mag_declination_source & MASK_USE_GEO_DECL) &&_NED_origin_initialised) {
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const Vector3f mag_earth_pred = Dcmf(Eulerf(0, -_mag_inclination_gps, _mag_declination_gps)) * Vector3f(_mag_strength_gps, 0, 0);
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_mag_sample_delayed.mag(2) = calculate_synthetic_mag_z_measurement(_mag_sample_delayed.mag, mag_earth_pred);
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_control_status.flags.synthetic_mag_z = true;
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} else {
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_control_status.flags.synthetic_mag_z = false;
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}
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}
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_delta_time_baro_us = _baro_sample_delayed.time_us;
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_baro_data_ready = _baro_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_baro_sample_delayed);
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// if we have a new baro sample save the delta time between this sample and the last sample which is
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// used below for baro offset calculations
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if (_baro_data_ready) {
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_delta_time_baro_us = _baro_sample_delayed.time_us - _delta_time_baro_us;
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}
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{
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// Get range data from buffer and check validity
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const bool is_rng_data_ready = _range_buffer.pop_first_older_than(_imu_sample_delayed.time_us, _range_sensor.getSampleAddress());
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_range_sensor.setDataReadiness(is_rng_data_ready);
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_range_sensor.runChecks(_imu_sample_delayed.time_us, _R_to_earth);
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// update range sensor angle parameters in case they have changed
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_range_sensor.setPitchOffset(_params.rng_sens_pitch);
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_range_sensor.setCosMaxTilt(_params.range_cos_max_tilt);
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}
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if (_range_sensor.isDataHealthy()) {
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// correct the range data for position offset relative to the IMU
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Vector3f pos_offset_body = _params.rng_pos_body - _params.imu_pos_body;
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Vector3f pos_offset_earth = _R_to_earth * pos_offset_body;
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_range_sensor.setRange(_range_sensor.getRange() + pos_offset_earth(2) / _range_sensor.getCosTilt());
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}
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// We don't fuse flow data immediately because we have to wait for the mid integration point to fall behind the fusion time horizon.
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// This means we stop looking for new data until the old data has been fused, unless we are not fusing optical flow,
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// in this case we need to empty the buffer
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if (!_flow_data_ready || !_control_status.flags.opt_flow) {
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_flow_data_ready = _flow_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_flow_sample_delayed)
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&& (_R_to_earth(2, 2) > _params.range_cos_max_tilt);
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}
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// check if we should fuse flow data for terrain estimation
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if (!_flow_for_terrain_data_ready && _flow_data_ready && _control_status.flags.in_air) {
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// only fuse flow for terrain if range data hasn't been fused for 5 seconds
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_flow_for_terrain_data_ready = isTimedOut(_time_last_hagl_fuse, (uint64_t)5E6);
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// only fuse flow for terrain if the main filter is not fusing flow and we are using gps
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_flow_for_terrain_data_ready &= (!_control_status.flags.opt_flow && _control_status.flags.gps);
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}
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_ev_data_ready = _ext_vision_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_ev_sample_delayed);
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_tas_data_ready = _airspeed_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_airspeed_sample_delayed);
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// check for height sensor timeouts and reset and change sensor if necessary
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controlHeightSensorTimeouts();
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// control use of observations for aiding
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controlMagFusion();
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controlOpticalFlowFusion();
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controlGpsFusion();
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controlAirDataFusion();
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controlBetaFusion();
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controlDragFusion();
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controlHeightFusion();
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// Additional data odoemtery data from an external estimator can be fused.
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controlExternalVisionFusion();
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// Additional horizontal velocity data from an auxiliary sensor can be fused
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controlAuxVelFusion();
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// Fake position measurement for constraining drift when no other velocity or position measurements
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controlFakePosFusion();
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// check if we are no longer fusing measurements that directly constrain velocity drift
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update_deadreckoning_status();
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}
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void Ekf::controlExternalVisionFusion()
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{
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// Check for new external vision data
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if (_ev_data_ready) {
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// if the ev data is not in a NED reference frame, then the transformation between EV and EKF navigation frames
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// needs to be calculated and the observations rotated into the EKF frame of reference
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if ((_params.fusion_mode & MASK_ROTATE_EV) && ((_params.fusion_mode & MASK_USE_EVPOS) || (_params.fusion_mode & MASK_USE_EVVEL)) && !_control_status.flags.ev_yaw) {
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// rotate EV measurements into the EKF Navigation frame
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calcExtVisRotMat();
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}
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// external vision aiding selection logic
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if (_control_status.flags.tilt_align && _control_status.flags.yaw_align) {
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// check for a external vision measurement that has fallen behind the fusion time horizon
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if (isRecent(_time_last_ext_vision, 2 * EV_MAX_INTERVAL)) {
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// turn on use of external vision measurements for position
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if (_params.fusion_mode & MASK_USE_EVPOS && !_control_status.flags.ev_pos) {
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_control_status.flags.ev_pos = true;
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resetHorizontalPosition();
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ECL_INFO_TIMESTAMPED("starting vision pos fusion");
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}
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// turn on use of external vision measurements for velocity
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if (_params.fusion_mode & MASK_USE_EVVEL && !_control_status.flags.ev_vel) {
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_control_status.flags.ev_vel = true;
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resetVelocity();
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ECL_INFO_TIMESTAMPED("starting vision vel fusion");
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}
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}
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}
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// external vision yaw aiding selection logic
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if (!_control_status.flags.gps && (_params.fusion_mode & MASK_USE_EVYAW) && !_control_status.flags.ev_yaw && _control_status.flags.tilt_align) {
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// don't start using EV data unless data is arriving frequently
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if (isRecent(_time_last_ext_vision, 2 * EV_MAX_INTERVAL)) {
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// reset the yaw angle to the value from the vision quaternion
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const Eulerf euler_obs(_ev_sample_delayed.quat);
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const float yaw = euler_obs(2);
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const float yaw_variance = fmaxf(_ev_sample_delayed.angVar, sq(1.0e-2f));
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resetQuatStateYaw(yaw, yaw_variance, true);
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// flag the yaw as aligned
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_control_status.flags.yaw_align = true;
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// turn on fusion of external vision yaw measurements and disable all magnetometer fusion
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_control_status.flags.ev_yaw = true;
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_control_status.flags.mag_dec = false;
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stopMagHdgFusion();
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stopMag3DFusion();
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ECL_INFO_TIMESTAMPED("starting vision yaw fusion");
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}
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}
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// determine if we should use the horizontal position observations
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if (_control_status.flags.ev_pos) {
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Vector3f ev_pos_obs_var;
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Vector2f ev_pos_innov_gates;
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// correct position and height for offset relative to IMU
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const Vector3f pos_offset_body = _params.ev_pos_body - _params.imu_pos_body;
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const Vector3f pos_offset_earth = _R_to_earth * pos_offset_body;
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_ev_sample_delayed.pos -= pos_offset_earth;
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// Use an incremental position fusion method for EV position data if GPS is also used
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if (_params.fusion_mode & MASK_USE_GPS) {
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_fuse_hpos_as_odom = true;
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} else {
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_fuse_hpos_as_odom = false;
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}
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if (_fuse_hpos_as_odom) {
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if (!_hpos_prev_available) {
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// no previous observation available to calculate position change
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_hpos_prev_available = true;
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} else {
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// calculate the change in position since the last measurement
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Vector3f ev_delta_pos = _ev_sample_delayed.pos - _pos_meas_prev;
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// rotate measurement into body frame is required when fusing with GPS
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ev_delta_pos = _R_ev_to_ekf * ev_delta_pos;
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// use the change in position since the last measurement
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_ev_pos_innov(0) = _state.pos(0) - _hpos_pred_prev(0) - ev_delta_pos(0);
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_ev_pos_innov(1) = _state.pos(1) - _hpos_pred_prev(1) - ev_delta_pos(1);
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// observation 1-STD error, incremental pos observation is expected to have more uncertainty
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Matrix3f ev_pos_var = matrix::diag(_ev_sample_delayed.posVar);
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ev_pos_var = _R_ev_to_ekf * ev_pos_var * _R_ev_to_ekf.transpose();
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ev_pos_obs_var(0) = fmaxf(ev_pos_var(0, 0), sq(0.5f));
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ev_pos_obs_var(1) = fmaxf(ev_pos_var(1, 1), sq(0.5f));
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}
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// record observation and estimate for use next time
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_pos_meas_prev = _ev_sample_delayed.pos;
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_hpos_pred_prev = _state.pos.xy();
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} else {
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// use the absolute position
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Vector3f ev_pos_meas = _ev_sample_delayed.pos;
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Matrix3f ev_pos_var = matrix::diag(_ev_sample_delayed.posVar);
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if (_params.fusion_mode & MASK_ROTATE_EV) {
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ev_pos_meas = _R_ev_to_ekf * ev_pos_meas;
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ev_pos_var = _R_ev_to_ekf * ev_pos_var * _R_ev_to_ekf.transpose();
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}
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_ev_pos_innov(0) = _state.pos(0) - ev_pos_meas(0);
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_ev_pos_innov(1) = _state.pos(1) - ev_pos_meas(1);
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ev_pos_obs_var(0) = fmaxf(ev_pos_var(0, 0), sq(0.01f));
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ev_pos_obs_var(1) = fmaxf(ev_pos_var(1, 1), sq(0.01f));
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// check if we have been deadreckoning too long
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if (isTimedOut(_time_last_hor_pos_fuse, _params.reset_timeout_max)) {
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// only reset velocity if we have no another source of aiding constraining it
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if (isTimedOut(_time_last_of_fuse, (uint64_t)1E6) &&
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isTimedOut(_time_last_hor_vel_fuse, (uint64_t)1E6)) {
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resetVelocity();
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}
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resetHorizontalPosition();
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}
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}
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// innovation gate size
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ev_pos_innov_gates(0) = fmaxf(_params.ev_pos_innov_gate, 1.0f);
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fuseHorizontalPosition(_ev_pos_innov, ev_pos_innov_gates, ev_pos_obs_var, _ev_pos_innov_var, _ev_pos_test_ratio);
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}
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// determine if we should use the velocity observations
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if (_control_status.flags.ev_vel) {
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Vector3f ev_vel_obs_var;
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Vector2f ev_vel_innov_gates;
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_ev_vel_innov = _state.vel - getVisionVelocityInEkfFrame();
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// check if we have been deadreckoning too long
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if (isTimedOut(_time_last_hor_vel_fuse, _params.reset_timeout_max)) {
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// only reset velocity if we have no another source of aiding constraining it
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if (isTimedOut(_time_last_of_fuse, (uint64_t)1E6) &&
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isTimedOut(_time_last_hor_pos_fuse, (uint64_t)1E6)) {
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resetVelocity();
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}
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}
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ev_vel_obs_var = matrix::max(getVisionVelocityVarianceInEkfFrame(), sq(0.05f));
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ev_vel_innov_gates.setAll(fmaxf(_params.ev_vel_innov_gate, 1.0f));
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fuseHorizontalVelocity(_ev_vel_innov, ev_vel_innov_gates,ev_vel_obs_var, _ev_vel_innov_var, _ev_vel_test_ratio);
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fuseVerticalVelocity(_ev_vel_innov, ev_vel_innov_gates, ev_vel_obs_var, _ev_vel_innov_var, _ev_vel_test_ratio);
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}
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// determine if we should use the yaw observation
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if (_control_status.flags.ev_yaw) {
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fuseHeading();
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}
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} else if ((_control_status.flags.ev_pos || _control_status.flags.ev_vel)
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&& isTimedOut(_time_last_ext_vision, (uint64_t)_params.reset_timeout_max)) {
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// Turn off EV fusion mode if no data has been received
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stopEvFusion();
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ECL_INFO_TIMESTAMPED("vision data stopped");
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}
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}
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void Ekf::controlOpticalFlowFusion()
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{
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// TODO: These motion checks run all the time. Pull them out of this function
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// Check if on ground motion is un-suitable for use of optical flow
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if (!_control_status.flags.in_air) {
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// When on ground check if the vehicle is being shaken or moved in a way that could cause a loss of navigation
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const float accel_norm = _accel_vec_filt.norm();
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const bool motion_is_excessive = ((accel_norm > (CONSTANTS_ONE_G * 1.5f)) // upper g limit
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|| (accel_norm < (CONSTANTS_ONE_G * 0.5f)) // lower g limit
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|| (_ang_rate_magnitude_filt > _flow_max_rate) // angular rate exceeds flow sensor limit
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|| (_R_to_earth(2,2) < cosf(math::radians(30.0f)))); // tilted excessively
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if (motion_is_excessive) {
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_time_bad_motion_us = _imu_sample_delayed.time_us;
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} else {
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_time_good_motion_us = _imu_sample_delayed.time_us;
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}
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} else {
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_time_bad_motion_us = 0;
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_time_good_motion_us = _imu_sample_delayed.time_us;
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}
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// Accumulate autopilot gyro data across the same time interval as the flow sensor
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_imu_del_ang_of += _imu_sample_delayed.delta_ang - _state.delta_ang_bias;
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_delta_time_of += _imu_sample_delayed.delta_ang_dt;
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// New optical flow data is available and is ready to be fused when the midpoint of the sample falls behind the fusion time horizon
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if (_flow_data_ready) {
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// Inhibit flow use if motion is un-suitable or we have good quality GPS
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// Apply hysteresis to prevent rapid mode switching
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float gps_err_norm_lim;
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if (_control_status.flags.opt_flow) {
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gps_err_norm_lim = 0.7f;
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} else {
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gps_err_norm_lim = 1.0f;
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}
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// Check if we are in-air and require optical flow to control position drift
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bool flow_required = _control_status.flags.in_air &&
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(_is_dead_reckoning // is doing inertial dead-reckoning so must constrain drift urgently
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|| (isOnlyActiveSourceOfHorizontalAiding(_control_status.flags.opt_flow))
|
|
|| (_control_status.flags.gps && (_gps_error_norm > gps_err_norm_lim))); // is using GPS, but GPS is bad
|
|
|
|
if (!_inhibit_flow_use && _control_status.flags.opt_flow) {
|
|
// inhibit use of optical flow if motion is unsuitable and we are not reliant on it for flight navigation
|
|
bool preflight_motion_not_ok = !_control_status.flags.in_air && ((_imu_sample_delayed.time_us - _time_good_motion_us) > (uint64_t)1E5);
|
|
bool flight_motion_not_ok = _control_status.flags.in_air && !isTerrainEstimateValid();
|
|
if ((preflight_motion_not_ok || flight_motion_not_ok) && !flow_required) {
|
|
_inhibit_flow_use = true;
|
|
}
|
|
} else if (_inhibit_flow_use && !_control_status.flags.opt_flow){
|
|
// allow use of optical flow if motion is suitable or we are reliant on it for flight navigation
|
|
bool preflight_motion_ok = !_control_status.flags.in_air && ((_imu_sample_delayed.time_us - _time_bad_motion_us) > (uint64_t)5E6);
|
|
bool flight_motion_ok = _control_status.flags.in_air && isRangeAidSuitable();
|
|
if (preflight_motion_ok || flight_motion_ok || flow_required) {
|
|
_inhibit_flow_use = false;
|
|
}
|
|
}
|
|
|
|
// Handle cases where we are using optical flow but are no longer able to because data is old
|
|
// or its use has been inhibited.
|
|
if (_control_status.flags.opt_flow) {
|
|
if (_inhibit_flow_use) {
|
|
stopFlowFusion();
|
|
_time_last_of_fuse = 0;
|
|
|
|
} else if (isTimedOut(_time_last_of_fuse, (uint64_t)_params.reset_timeout_max)) {
|
|
stopFlowFusion();
|
|
}
|
|
}
|
|
|
|
// optical flow fusion mode selection logic
|
|
if ((_params.fusion_mode & MASK_USE_OF) // optical flow has been selected by the user
|
|
&& !_control_status.flags.opt_flow // we are not yet using flow data
|
|
&& _control_status.flags.tilt_align // we know our tilt attitude
|
|
&& !_inhibit_flow_use
|
|
&& isTerrainEstimateValid())
|
|
{
|
|
// If the heading is not aligned, reset the yaw and magnetic field states
|
|
if (!_control_status.flags.yaw_align) {
|
|
_control_status.flags.yaw_align = resetMagHeading(_mag_lpf.getState());
|
|
}
|
|
|
|
// If the heading is valid and use is not inhibited , start using optical flow aiding
|
|
if (_control_status.flags.yaw_align) {
|
|
// set the flag and reset the fusion timeout
|
|
_control_status.flags.opt_flow = true;
|
|
_time_last_of_fuse = _time_last_imu;
|
|
|
|
// if we are not using GPS or external vision aiding, then the velocity and position states and covariances need to be set
|
|
const bool flow_aid_only = !isOtherSourceOfHorizontalAidingThan(_control_status.flags.opt_flow);
|
|
if (flow_aid_only) {
|
|
// TODO: Issue: First time we want to reset the optical flow velocity
|
|
// we will use _flow_compensated_XY_rad in the resetVelocity() function,
|
|
// but _flow_compensated_XY_rad is this zero as it gets updated for the first time below here.
|
|
resetVelocity();
|
|
resetHorizontalPosition();
|
|
|
|
// align the output observer to the EKF states
|
|
alignOutputFilter();
|
|
}
|
|
}
|
|
|
|
} else if (!(_params.fusion_mode & MASK_USE_OF)) {
|
|
_control_status.flags.opt_flow = false;
|
|
}
|
|
|
|
// handle the case when we have optical flow, are reliant on it, but have not been using it for an extended period
|
|
if (isOnlyActiveSourceOfHorizontalAiding(_control_status.flags.opt_flow)) {
|
|
|
|
bool do_reset = isTimedOut(_time_last_of_fuse, _params.reset_timeout_max);
|
|
|
|
if (do_reset) {
|
|
resetVelocity();
|
|
resetHorizontalPosition();
|
|
}
|
|
}
|
|
|
|
// Only fuse optical flow if valid body rate compensation data is available
|
|
if (calcOptFlowBodyRateComp()) {
|
|
|
|
bool flow_quality_good = (_flow_sample_delayed.quality >= _params.flow_qual_min);
|
|
|
|
if (!flow_quality_good && !_control_status.flags.in_air) {
|
|
// when on the ground with poor flow quality, assume zero ground relative velocity and LOS rate
|
|
_flow_compensated_XY_rad.setZero();
|
|
} else {
|
|
// compensate for body motion to give a LOS rate
|
|
_flow_compensated_XY_rad = _flow_sample_delayed.flow_xy_rad - _flow_sample_delayed.gyro_xyz.xy();
|
|
}
|
|
} else {
|
|
// don't use this flow data and wait for the next data to arrive
|
|
_flow_data_ready = false;
|
|
}
|
|
}
|
|
|
|
// Wait until the midpoint of the flow sample has fallen behind the fusion time horizon
|
|
if (_flow_data_ready && (_imu_sample_delayed.time_us > _flow_sample_delayed.time_us - uint32_t(1e6f * _flow_sample_delayed.dt) / 2)) {
|
|
// Fuse optical flow LOS rate observations into the main filter only if height above ground has been updated recently
|
|
// but use a relaxed time criteria to enable it to coast through bad range finder data
|
|
if (_control_status.flags.opt_flow && isRecent(_time_last_hagl_fuse, (uint64_t)10e6)) {
|
|
fuseOptFlow();
|
|
_last_known_posNE = _state.pos.xy();
|
|
}
|
|
|
|
_flow_data_ready = false;
|
|
}
|
|
}
|
|
|
|
void Ekf::controlGpsFusion()
|
|
{
|
|
// Check for new GPS data that has fallen behind the fusion time horizon
|
|
if (_gps_data_ready) {
|
|
|
|
// Detect if coming back after significant time without GPS data
|
|
bool gps_signal_was_lost = isTimedOut(_time_prev_gps_us, 1000000);
|
|
|
|
|
|
if (!(_params.fusion_mode & MASK_USE_GPSYAW)
|
|
|| _is_gps_yaw_faulty) {
|
|
|
|
stopGpsYawFusion();
|
|
|
|
} else {
|
|
if (ISFINITE(_gps_sample_delayed.yaw)) {
|
|
|
|
if (!_control_status.flags.gps_yaw
|
|
&& _control_status.flags.tilt_align
|
|
&& !_gps_hgt_intermittent) {
|
|
|
|
// Activate GPS yaw fusion
|
|
if (resetGpsAntYaw()) {
|
|
_control_status.flags.yaw_align = true;
|
|
|
|
startGpsYawFusion();
|
|
|
|
ECL_INFO_TIMESTAMPED("starting GPS yaw fusion");
|
|
}
|
|
}
|
|
|
|
if (_control_status.flags.gps_yaw) {
|
|
fuseGpsAntYaw();
|
|
}
|
|
}
|
|
|
|
// Check if the data is constantly fused by the estimator,
|
|
// if not, declare the sensor faulty and stop the fusion
|
|
// By doing this, another source of yaw aiding is allowed to start
|
|
if (isTimedOut(_time_last_gps_yaw_fuse, (uint64_t)5e6)
|
|
&& _control_status.flags.gps_yaw) {
|
|
_is_gps_yaw_faulty = true;
|
|
stopGpsYawFusion();
|
|
}
|
|
}
|
|
|
|
// Determine if we should use GPS aiding for velocity and horizontal position
|
|
// To start using GPS we need angular alignment completed, the local NED origin set and GPS data that has not failed checks recently
|
|
bool gps_checks_passing = isTimedOut(_last_gps_fail_us, (uint64_t)5e6);
|
|
bool gps_checks_failing = isTimedOut(_last_gps_pass_us, (uint64_t)5e6);
|
|
if ((_params.fusion_mode & MASK_USE_GPS) && !_control_status.flags.gps) {
|
|
if (_control_status.flags.tilt_align && _NED_origin_initialised && gps_checks_passing) {
|
|
// If the heading is not aligned, reset the yaw and magnetic field states
|
|
// Do not use external vision for yaw if using GPS because yaw needs to be
|
|
// defined relative to an NED reference frame
|
|
const bool want_to_reset_mag_heading = !_control_status.flags.yaw_align ||
|
|
_control_status.flags.ev_yaw ||
|
|
_mag_inhibit_yaw_reset_req;
|
|
if (want_to_reset_mag_heading && canResetMagHeading()) {
|
|
_control_status.flags.ev_yaw = false;
|
|
_control_status.flags.yaw_align = resetMagHeading(_mag_lpf.getState());
|
|
// Handle the special case where we have not been constraining yaw drift or learning yaw bias due
|
|
// to assumed invalid mag field associated with indoor operation with a downwards looking flow sensor.
|
|
if (_mag_inhibit_yaw_reset_req) {
|
|
_mag_inhibit_yaw_reset_req = false;
|
|
// Zero the yaw bias covariance and set the variance to the initial alignment uncertainty
|
|
P.uncorrelateCovarianceSetVariance<1>(12, sq(_params.switch_on_gyro_bias * FILTER_UPDATE_PERIOD_S));
|
|
}
|
|
}
|
|
|
|
// If the heading is valid start using gps aiding
|
|
if (_control_status.flags.yaw_align) {
|
|
resetHorizontalPositionToGps();
|
|
|
|
// when adding with optical flow,
|
|
// velocity reset is not necessary
|
|
if (!_control_status.flags.opt_flow) {
|
|
resetVelocityToGps();
|
|
}
|
|
|
|
ECL_INFO_TIMESTAMPED("starting GPS fusion");
|
|
_control_status.flags.gps = true;
|
|
_time_last_gps = _time_last_imu;
|
|
}
|
|
}
|
|
|
|
} else if (!(_params.fusion_mode & MASK_USE_GPS)) {
|
|
_control_status.flags.gps = false;
|
|
|
|
}
|
|
|
|
// Handle the case where we are using GPS and another source of aiding and GPS is failing checks
|
|
if (_control_status.flags.gps && gps_checks_failing && isOtherSourceOfHorizontalAidingThan(_control_status.flags.gps)) {
|
|
stopGpsFusion();
|
|
// Reset position state to external vision if we are going to use absolute values
|
|
if (_control_status.flags.ev_pos && !(_params.fusion_mode & MASK_ROTATE_EV)) {
|
|
resetHorizontalPosition();
|
|
}
|
|
ECL_WARN_TIMESTAMPED("GPS quality poor - stopping use");
|
|
}
|
|
|
|
// handle case where we are not currently using GPS, but need to align yaw angle using EKF-GSF before
|
|
// we can start using GPS
|
|
bool align_yaw_using_gsf = !_control_status.flags.gps && _do_ekfgsf_yaw_reset && isTimedOut(_ekfgsf_yaw_reset_time, 5000000);
|
|
if (align_yaw_using_gsf) {
|
|
if (resetYawToEKFGSF()) {
|
|
_ekfgsf_yaw_reset_time = _time_last_imu;
|
|
_do_ekfgsf_yaw_reset = false;
|
|
}
|
|
}
|
|
|
|
// handle the case when we now have GPS, but have not been fusing it for an extended period
|
|
if (_control_status.flags.gps) {
|
|
// We are relying on aiding to constrain drift so after a specified time
|
|
// with no aiding we need to do something
|
|
bool do_vel_pos_reset = isTimedOut(_time_last_hor_pos_fuse, _params.reset_timeout_max)
|
|
&& isTimedOut(_time_last_delpos_fuse, _params.reset_timeout_max)
|
|
&& isTimedOut(_time_last_hor_vel_fuse, _params.reset_timeout_max)
|
|
&& isTimedOut(_time_last_of_fuse, _params.reset_timeout_max);
|
|
|
|
// We haven't had an absolute position fix for a longer time so need to do something
|
|
do_vel_pos_reset = do_vel_pos_reset || isTimedOut(_time_last_hor_pos_fuse, 2 * _params.reset_timeout_max);
|
|
|
|
/* Logic controlling the reset of navigation filter yaw to the EKF-GSF estimate to recover from loss of
|
|
navigation casued by a bad yaw estimate.
|
|
|
|
A rapid reset to the EKF-GSF estimate is performed after a recent takeoff if horizontal velocity
|
|
innovation checks fail. This enables recovery from a bad yaw estimate. After 30 seconds from takeoff,
|
|
different test criteria are used that take longer to trigger and reduce false positives. A reset is
|
|
not performed if the fault condition was present before flight to prevent triggering due to GPS glitches
|
|
or other sensor errors.
|
|
|
|
The yaw reset to the EKF-GSF estimate can be requested externally at any time during flight.
|
|
|
|
The total number of resets allowed per boot cycle is limited.
|
|
|
|
The minimum time interval between resets to the EKF-GSF estimate is limited to allow the EKF-GSF time
|
|
to improve its estimate if the previous reset was not successful.
|
|
|
|
A reset is not performed when getting GPS back after a significant period of no data because the timeout
|
|
could have been caused by bad GPS.
|
|
*/
|
|
|
|
if (!_control_status.flags.in_air) {
|
|
_time_last_on_ground_us = _time_last_imu;
|
|
}
|
|
|
|
const bool recent_takeoff_nav_failure = _control_status.flags.in_air &&
|
|
!isTimedOut(_time_last_on_ground_us, 30000000) &&
|
|
isTimedOut(_time_last_hor_vel_fuse, _params.EKFGSF_reset_delay) &&
|
|
(_time_last_hor_vel_fuse > _time_last_on_ground_us);
|
|
|
|
const bool inflight_nav_failure = _control_status.flags.in_air &&
|
|
do_vel_pos_reset &&
|
|
(_time_last_hor_vel_fuse > _time_last_on_ground_us) &&
|
|
(_time_last_hor_pos_fuse > _time_last_on_ground_us);
|
|
|
|
const bool do_yaw_vel_pos_reset = (_do_ekfgsf_yaw_reset || recent_takeoff_nav_failure || inflight_nav_failure) &&
|
|
_ekfgsf_yaw_reset_count < _params.EKFGSF_reset_count_limit &&
|
|
isTimedOut(_ekfgsf_yaw_reset_time, 5000000) &&
|
|
!gps_signal_was_lost;
|
|
|
|
if (do_yaw_vel_pos_reset) {
|
|
if (resetYawToEKFGSF()) {
|
|
_ekfgsf_yaw_reset_time = _time_last_imu;
|
|
_do_ekfgsf_yaw_reset = false;
|
|
_ekfgsf_yaw_reset_count++;
|
|
|
|
// Reset the timeout counters
|
|
_time_last_hor_pos_fuse = _time_last_imu;
|
|
_time_last_delpos_fuse = _time_last_imu;
|
|
_time_last_hor_vel_fuse = _time_last_imu;
|
|
_time_last_of_fuse = _time_last_imu;
|
|
}
|
|
|
|
} else if (do_vel_pos_reset) {
|
|
// use GPS velocity data to check and correct yaw angle if a FW vehicle
|
|
if (_control_status.flags.fixed_wing && _control_status.flags.in_air) {
|
|
// if flying a fixed wing aircraft, do a complete reset that includes yaw
|
|
_control_status.flags.mag_aligned_in_flight = realignYawGPS();
|
|
}
|
|
|
|
resetVelocity();
|
|
resetHorizontalPosition();
|
|
_velpos_reset_request = false;
|
|
ECL_WARN_TIMESTAMPED("GPS fusion timeout - reset to GPS");
|
|
|
|
// Reset the timeout counters
|
|
_time_last_hor_pos_fuse = _time_last_imu;
|
|
_time_last_hor_vel_fuse = _time_last_imu;
|
|
}
|
|
}
|
|
|
|
// Only use GPS data for position and velocity aiding if enabled
|
|
if (_control_status.flags.gps) {
|
|
|
|
Vector2f gps_vel_innov_gates; // [horizontal vertical]
|
|
Vector2f gps_pos_innov_gates; // [horizontal vertical]
|
|
Vector3f gps_vel_obs_var;
|
|
Vector3f gps_pos_obs_var;
|
|
|
|
// correct velocity for offset relative to IMU
|
|
const Vector3f pos_offset_body = _params.gps_pos_body - _params.imu_pos_body;
|
|
const Vector3f vel_offset_body = _ang_rate_delayed_raw % pos_offset_body;
|
|
const Vector3f vel_offset_earth = _R_to_earth * vel_offset_body;
|
|
_gps_sample_delayed.vel -= vel_offset_earth;
|
|
|
|
// correct position and height for offset relative to IMU
|
|
const Vector3f pos_offset_earth = _R_to_earth * pos_offset_body;
|
|
_gps_sample_delayed.pos -= pos_offset_earth.xy();
|
|
_gps_sample_delayed.hgt += pos_offset_earth(2);
|
|
|
|
const float lower_limit = fmaxf(_params.gps_pos_noise, 0.01f);
|
|
|
|
if (isOtherSourceOfHorizontalAidingThan(_control_status.flags.gps)) {
|
|
// if we are using other sources of aiding, then relax the upper observation
|
|
// noise limit which prevents bad GPS perturbing the position estimate
|
|
gps_pos_obs_var(0) = gps_pos_obs_var(1) = sq(fmaxf(_gps_sample_delayed.hacc, lower_limit));
|
|
|
|
} else {
|
|
// if we are not using another source of aiding, then we are reliant on the GPS
|
|
// observations to constrain attitude errors and must limit the observation noise value.
|
|
float upper_limit = fmaxf(_params.pos_noaid_noise, lower_limit);
|
|
gps_pos_obs_var(0) = gps_pos_obs_var(1) = sq(math::constrain(_gps_sample_delayed.hacc, lower_limit, upper_limit));
|
|
}
|
|
|
|
gps_vel_obs_var.setAll(sq(fmaxf(_gps_sample_delayed.sacc, _params.gps_vel_noise)));
|
|
gps_vel_obs_var(2) = sq(1.5f) * gps_vel_obs_var(2);
|
|
|
|
// calculate innovations
|
|
_gps_vel_innov = _state.vel - _gps_sample_delayed.vel;
|
|
_gps_pos_innov.xy() = Vector2f(_state.pos) - _gps_sample_delayed.pos;
|
|
|
|
// set innovation gate size
|
|
gps_pos_innov_gates(0) = fmaxf(_params.gps_pos_innov_gate, 1.0f);
|
|
gps_vel_innov_gates(0) = gps_vel_innov_gates(1) = fmaxf(_params.gps_vel_innov_gate, 1.0f);
|
|
|
|
// fuse GPS measurement
|
|
fuseHorizontalVelocity(_gps_vel_innov, gps_vel_innov_gates,gps_vel_obs_var, _gps_vel_innov_var, _gps_vel_test_ratio);
|
|
fuseVerticalVelocity(_gps_vel_innov, gps_vel_innov_gates, gps_vel_obs_var, _gps_vel_innov_var, _gps_vel_test_ratio);
|
|
fuseHorizontalPosition(_gps_pos_innov, gps_pos_innov_gates, gps_pos_obs_var, _gps_pos_innov_var, _gps_pos_test_ratio);
|
|
}
|
|
|
|
} else if (_control_status.flags.gps && (_imu_sample_delayed.time_us - _gps_sample_delayed.time_us > (uint64_t)10e6)) {
|
|
stopGpsFusion();
|
|
ECL_WARN_TIMESTAMPED("GPS data stopped");
|
|
} else if (_control_status.flags.gps && (_imu_sample_delayed.time_us - _gps_sample_delayed.time_us > (uint64_t)1e6) && isOtherSourceOfHorizontalAidingThan(_control_status.flags.gps)) {
|
|
// Handle the case where we are fusing another position source along GPS,
|
|
// stop waiting for GPS after 1 s of lost signal
|
|
stopGpsFusion();
|
|
ECL_WARN_TIMESTAMPED("GPS data stopped, using only EV or OF");
|
|
}
|
|
}
|
|
|
|
void Ekf::controlHeightSensorTimeouts()
|
|
{
|
|
/*
|
|
* Handle the case where we have not fused height measurements recently and
|
|
* uncertainty exceeds the max allowable. Reset using the best available height
|
|
* measurement source, continue using it after the reset and declare the current
|
|
* source failed if we have switched.
|
|
*/
|
|
|
|
checkVerticalAccelerationHealth();
|
|
|
|
// check if height is continuously failing because of accel errors
|
|
bool continuous_bad_accel_hgt = isTimedOut(_time_good_vert_accel, (uint64_t)_params.bad_acc_reset_delay_us);
|
|
|
|
// check if height has been inertial deadreckoning for too long
|
|
bool hgt_fusion_timeout = isTimedOut(_time_last_hgt_fuse, (uint64_t)5e6);
|
|
|
|
if (hgt_fusion_timeout || continuous_bad_accel_hgt) {
|
|
|
|
bool request_height_reset = false;
|
|
const char* failing_height_source = nullptr;
|
|
const char* new_height_source = nullptr;
|
|
|
|
if (_control_status.flags.baro_hgt) {
|
|
// check if GPS height is available
|
|
const gpsSample &gps_init = _gps_buffer.get_newest();
|
|
const bool gps_hgt_accurate = (gps_init.vacc < _params.req_vacc);
|
|
|
|
// check for inertial sensing errors in the last BADACC_PROBATION seconds
|
|
const bool prev_bad_vert_accel = isRecent(_time_bad_vert_accel, BADACC_PROBATION);
|
|
|
|
// reset to GPS if adequate GPS data is available and the timeout cannot be blamed on IMU data
|
|
const bool reset_to_gps = !_gps_hgt_intermittent &&
|
|
((gps_hgt_accurate && !prev_bad_vert_accel) || _baro_hgt_faulty);
|
|
|
|
if (reset_to_gps) {
|
|
// set height sensor health
|
|
_baro_hgt_faulty = true;
|
|
|
|
startGpsHgtFusion();
|
|
|
|
request_height_reset = true;
|
|
failing_height_source = "baro";
|
|
new_height_source = "gps";
|
|
|
|
} else if (!_baro_hgt_faulty) {
|
|
request_height_reset = true;
|
|
failing_height_source = "baro";
|
|
new_height_source = "baro";
|
|
}
|
|
|
|
} else if (_control_status.flags.gps_hgt) {
|
|
// check if GPS height is available
|
|
const gpsSample &gps_init = _gps_buffer.get_newest();
|
|
const bool gps_hgt_accurate = (gps_init.vacc < _params.req_vacc);
|
|
|
|
// check the baro height source for consistency and freshness
|
|
const baroSample &baro_init = _baro_buffer.get_newest();
|
|
const float baro_innov = _state.pos(2) - (_hgt_sensor_offset - baro_init.hgt + _baro_hgt_offset);
|
|
const bool baro_data_consistent = fabsf(baro_innov) < (sq(_params.baro_noise) + P(9,9)) * sq(_params.baro_innov_gate);
|
|
|
|
// if baro data is acceptable and GPS data is inaccurate, reset height to baro
|
|
const bool reset_to_baro = !_baro_hgt_faulty &&
|
|
((baro_data_consistent && !gps_hgt_accurate) ||
|
|
_gps_hgt_intermittent);
|
|
|
|
if (reset_to_baro) {
|
|
startBaroHgtFusion();
|
|
|
|
request_height_reset = true;
|
|
failing_height_source = "gps";
|
|
new_height_source = "baro";
|
|
|
|
} else if (!_gps_hgt_intermittent) {
|
|
request_height_reset = true;
|
|
failing_height_source = "gps";
|
|
new_height_source = "gps";
|
|
}
|
|
|
|
} else if (_control_status.flags.rng_hgt) {
|
|
|
|
if (_range_sensor.isHealthy()) {
|
|
request_height_reset = true;
|
|
failing_height_source = "rng";
|
|
new_height_source = "rng";
|
|
|
|
} else if (!_baro_hgt_faulty) {
|
|
startBaroHgtFusion();
|
|
|
|
request_height_reset = true;
|
|
failing_height_source = "rng";
|
|
new_height_source = "baro";
|
|
}
|
|
|
|
} else if (_control_status.flags.ev_hgt) {
|
|
// check if vision data is available
|
|
const extVisionSample &ev_init = _ext_vision_buffer.get_newest();
|
|
const bool ev_data_available = isRecent(ev_init.time_us, 2 * EV_MAX_INTERVAL);
|
|
|
|
if (ev_data_available) {
|
|
request_height_reset = true;
|
|
failing_height_source = "ev";
|
|
new_height_source = "ev";
|
|
|
|
} else if (!_baro_hgt_faulty) {
|
|
startBaroHgtFusion();
|
|
|
|
request_height_reset = true;
|
|
failing_height_source = "ev";
|
|
new_height_source = "baro";
|
|
}
|
|
}
|
|
|
|
if (failing_height_source && new_height_source) {
|
|
ECL_WARN("%s hgt timeout - reset to %s", failing_height_source, new_height_source);
|
|
}
|
|
|
|
// Reset vertical position and velocity states to the last measurement
|
|
if (request_height_reset) {
|
|
resetHeight();
|
|
// Reset the timout timer
|
|
_time_last_hgt_fuse = _time_last_imu;
|
|
}
|
|
}
|
|
}
|
|
|
|
void Ekf::checkVerticalAccelerationHealth()
|
|
{
|
|
// Check for IMU accelerometer vibration induced clipping as evidenced by the vertical
|
|
// innovations being positive and not stale.
|
|
// Clipping causes the average accel reading to move towards zero which makes the INS
|
|
// think it is falling and produces positive vertical innovations
|
|
|
|
const float var_product_lim = sq(_params.vert_innov_test_lim) * sq(_params.vert_innov_test_lim);
|
|
const bool is_fusing_gps_vel = !_gps_hgt_intermittent;
|
|
const bool is_fusing_baro_alt = _control_status.flags.baro_hgt && !_baro_hgt_faulty;
|
|
const bool are_vertical_pos_and_vel_independant = is_fusing_gps_vel && is_fusing_baro_alt; // TODO: should we add range hgt here?
|
|
const float pos_vel_innov_product = _gps_pos_innov(2) * fmaxf(fabsf(_gps_vel_innov(2)),fabsf(_ev_vel_innov(2)));
|
|
const float pos_vel_innov_var_product = _gps_pos_innov_var(2) * fmaxf(fabsf(_gps_vel_innov_var(2)),fabsf(_ev_vel_innov_var(2)));
|
|
const bool are_pos_vel_sensor_in_agreement = sq(pos_vel_innov_product) > var_product_lim * (pos_vel_innov_var_product);
|
|
|
|
// A positive innovation indicates that the inertial nav thinks it is falling
|
|
// This is caused by average of the Z accelerometer being 0, due to clipping
|
|
const bool is_inertial_nav_falling = _gps_vel_innov(2) > 0.0f || _ev_vel_innov(2) > 0.0f;
|
|
|
|
const bool bad_vert_accel = are_vertical_pos_and_vel_independant &&
|
|
are_pos_vel_sensor_in_agreement &&
|
|
is_inertial_nav_falling;
|
|
|
|
if (bad_vert_accel) {
|
|
_time_bad_vert_accel = _time_last_imu;
|
|
|
|
} else {
|
|
_time_good_vert_accel = _time_last_imu;
|
|
}
|
|
|
|
// declare a bad vertical acceleration measurement and make the declaration persist
|
|
// for a minimum of BADACC_PROBATION seconds
|
|
if (_bad_vert_accel_detected) {
|
|
_bad_vert_accel_detected = isRecent(_time_bad_vert_accel, BADACC_PROBATION);
|
|
|
|
} else {
|
|
_bad_vert_accel_detected = bad_vert_accel;
|
|
}
|
|
}
|
|
|
|
void Ekf::controlHeightFusion()
|
|
{
|
|
checkRangeAidSuitability();
|
|
const bool do_range_aid = (_params.range_aid == 1) && isRangeAidSuitable();
|
|
|
|
bool fuse_height = false;
|
|
|
|
switch (_params.vdist_sensor_type) {
|
|
default:
|
|
ECL_ERR("Invalid hgt mode: %d", _params.vdist_sensor_type);
|
|
|
|
// FALLTHROUGH
|
|
case VDIST_SENSOR_BARO:
|
|
if (do_range_aid && _range_sensor.isDataHealthy()) {
|
|
setControlRangeHeight();
|
|
fuse_height = true;
|
|
|
|
// we have just switched to using range finder, calculate height sensor offset such that current
|
|
// measurement matches our current height estimate
|
|
if (_control_status_prev.flags.rng_hgt != _control_status.flags.rng_hgt) {
|
|
_hgt_sensor_offset = _terrain_vpos;
|
|
}
|
|
|
|
} else if (!do_range_aid && _baro_data_ready && !_baro_hgt_faulty) {
|
|
startBaroHgtFusion();
|
|
fuse_height = true;
|
|
|
|
} else if (_control_status.flags.gps_hgt && _gps_data_ready && !_gps_hgt_intermittent) {
|
|
// switch to gps if there was a reset to gps
|
|
fuse_height = true;
|
|
|
|
// we have just switched to using gps height, calculate height sensor offset such that current
|
|
// measurement matches our current height estimate
|
|
if (_control_status_prev.flags.gps_hgt != _control_status.flags.gps_hgt) {
|
|
_hgt_sensor_offset = _gps_sample_delayed.hgt - _gps_alt_ref + _state.pos(2);
|
|
}
|
|
}
|
|
|
|
break;
|
|
|
|
case VDIST_SENSOR_RANGE:
|
|
if (_range_sensor.isDataHealthy()) {
|
|
setControlRangeHeight();
|
|
fuse_height = true;
|
|
|
|
if (_control_status_prev.flags.rng_hgt != _control_status.flags.rng_hgt) {
|
|
// we have just switched to using range finder, calculate height sensor offset such that current
|
|
// measurement matches our current height estimate
|
|
// use the parameter rng_gnd_clearance if on ground to avoid a noisy offset initialization (e.g. sonar)
|
|
if (_control_status.flags.in_air && isTerrainEstimateValid()) {
|
|
_hgt_sensor_offset = _terrain_vpos;
|
|
|
|
} else if (_control_status.flags.in_air) {
|
|
_hgt_sensor_offset = _range_sensor.getDistBottom() + _state.pos(2);
|
|
|
|
} else {
|
|
_hgt_sensor_offset = _params.rng_gnd_clearance;
|
|
}
|
|
}
|
|
|
|
} else if (_baro_data_ready && !_baro_hgt_faulty) {
|
|
startBaroHgtFusion();
|
|
fuse_height = true;
|
|
}
|
|
|
|
break;
|
|
|
|
case VDIST_SENSOR_GPS:
|
|
|
|
// NOTE: emergency fallback due to extended loss of currently selected sensor data or failure
|
|
// to pass innovation cinsistency checks is handled elsewhere in Ekf::controlHeightSensorTimeouts.
|
|
// Do switching between GPS and rangefinder if using range finder as a height source when close
|
|
// to ground and moving slowly. Also handle switch back from emergency Baro sensor when GPS recovers.
|
|
if (!_control_status_prev.flags.rng_hgt && do_range_aid && _range_sensor.isDataHealthy()) {
|
|
setControlRangeHeight();
|
|
|
|
// we have just switched to using range finder, calculate height sensor offset such that current
|
|
// measurement matches our current height estimate
|
|
_hgt_sensor_offset = _terrain_vpos;
|
|
|
|
} else if (_control_status_prev.flags.rng_hgt && !do_range_aid) {
|
|
// must stop using range finder so find another sensor now
|
|
if (!_gps_hgt_intermittent && _gps_checks_passed) {
|
|
// GPS quality OK
|
|
startGpsHgtFusion();
|
|
} else if (!_baro_hgt_faulty) {
|
|
// Use baro as a fallback
|
|
startBaroHgtFusion();
|
|
}
|
|
} else if (_control_status.flags.baro_hgt && !do_range_aid && !_gps_hgt_intermittent && _gps_checks_passed) {
|
|
// In baro fallback mode and GPS has recovered so start using it
|
|
startGpsHgtFusion();
|
|
}
|
|
if (_control_status.flags.gps_hgt && _gps_data_ready) {
|
|
fuse_height = true;
|
|
} else if (_control_status.flags.rng_hgt && _range_sensor.isDataHealthy()) {
|
|
fuse_height = true;
|
|
} else if (_control_status.flags.baro_hgt && _baro_data_ready && !_baro_hgt_faulty) {
|
|
fuse_height = true;
|
|
}
|
|
break;
|
|
|
|
case VDIST_SENSOR_EV:
|
|
|
|
// don't start using EV data unless data is arriving frequently
|
|
if (!_control_status.flags.ev_hgt && isRecent(_time_last_ext_vision, 2 * EV_MAX_INTERVAL)) {
|
|
fuse_height = true;
|
|
setControlEVHeight();
|
|
resetHeight();
|
|
}
|
|
|
|
if (_control_status.flags.baro_hgt && _baro_data_ready && !_baro_hgt_faulty) {
|
|
// switch to baro if there was a reset to baro
|
|
fuse_height = true;
|
|
}
|
|
|
|
// determine if we should use the vertical position observation
|
|
if (_control_status.flags.ev_hgt) {
|
|
fuse_height = true;
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
updateBaroHgtOffset();
|
|
|
|
if (isTimedOut(_time_last_hgt_fuse, 2 * RNG_MAX_INTERVAL) && _control_status.flags.rng_hgt
|
|
&& (!_range_sensor.isDataHealthy())) {
|
|
|
|
// If we are supposed to be using range finder data as the primary height sensor, have missed or rejected measurements
|
|
// and are on the ground, then synthesise a measurement at the expected on ground value
|
|
if (!_control_status.flags.in_air) {
|
|
_range_sensor.setRange(_params.rng_gnd_clearance);
|
|
_range_sensor.setDataReadiness(true);
|
|
_range_sensor.setValidity(true); // bypass the checks
|
|
}
|
|
|
|
fuse_height = true;
|
|
}
|
|
|
|
if (fuse_height) {
|
|
if (_control_status.flags.baro_hgt) {
|
|
Vector2f baro_hgt_innov_gate;
|
|
Vector3f baro_hgt_obs_var;
|
|
|
|
// vertical position innovation - baro measurement has opposite sign to earth z axis
|
|
_baro_hgt_innov(2) = _state.pos(2) + _baro_sample_delayed.hgt - _baro_hgt_offset;
|
|
// observation variance - user parameter defined
|
|
baro_hgt_obs_var(2) = sq(fmaxf(_params.baro_noise, 0.01f));
|
|
// innovation gate size
|
|
baro_hgt_innov_gate(1) = fmaxf(_params.baro_innov_gate, 1.0f);
|
|
|
|
// Compensate for positive static pressure transients (negative vertical position innovations)
|
|
// caused by rotor wash ground interaction by applying a temporary deadzone to baro innovations.
|
|
float deadzone_start = 0.0f;
|
|
float deadzone_end = deadzone_start + _params.gnd_effect_deadzone;
|
|
|
|
if (_control_status.flags.gnd_effect) {
|
|
if (_baro_hgt_innov(2) < -deadzone_start) {
|
|
if (_baro_hgt_innov(2) <= -deadzone_end) {
|
|
_baro_hgt_innov(2) += deadzone_end;
|
|
|
|
} else {
|
|
_baro_hgt_innov(2) = -deadzone_start;
|
|
}
|
|
}
|
|
}
|
|
// fuse height information
|
|
fuseVerticalPosition(_baro_hgt_innov,baro_hgt_innov_gate,
|
|
baro_hgt_obs_var, _baro_hgt_innov_var,_baro_hgt_test_ratio);
|
|
|
|
} else if (_control_status.flags.gps_hgt) {
|
|
Vector2f gps_hgt_innov_gate;
|
|
Vector3f gps_hgt_obs_var;
|
|
// vertical position innovation - gps measurement has opposite sign to earth z axis
|
|
_gps_pos_innov(2) = _state.pos(2) + _gps_sample_delayed.hgt - _gps_alt_ref - _hgt_sensor_offset;
|
|
// observation variance - receiver defined and parameter limited
|
|
// use scaled horizontal position accuracy assuming typical ratio of VDOP/HDOP
|
|
const float lower_limit = fmaxf(_params.gps_pos_noise, 0.01f);
|
|
const float upper_limit = fmaxf(_params.pos_noaid_noise, lower_limit);
|
|
gps_hgt_obs_var(2) = sq(1.5f * math::constrain(_gps_sample_delayed.vacc, lower_limit, upper_limit));
|
|
// innovation gate size
|
|
gps_hgt_innov_gate(1) = fmaxf(_params.baro_innov_gate, 1.0f);
|
|
// fuse height information
|
|
fuseVerticalPosition(_gps_pos_innov,gps_hgt_innov_gate,
|
|
gps_hgt_obs_var, _gps_pos_innov_var,_gps_pos_test_ratio);
|
|
|
|
} else if (_control_status.flags.rng_hgt) {
|
|
Vector2f rng_hgt_innov_gate;
|
|
Vector3f rng_hgt_obs_var;
|
|
// use range finder with tilt correction
|
|
_rng_hgt_innov(2) = _state.pos(2) - (-math::max(_range_sensor.getDistBottom(),
|
|
_params.rng_gnd_clearance)) - _hgt_sensor_offset;
|
|
// observation variance - user parameter defined
|
|
rng_hgt_obs_var(2) = fmaxf(sq(_params.range_noise)
|
|
+ sq(_params.range_noise_scaler * _range_sensor.getDistBottom()), 0.01f);
|
|
// innovation gate size
|
|
rng_hgt_innov_gate(1) = fmaxf(_params.range_innov_gate, 1.0f);
|
|
// fuse height information
|
|
fuseVerticalPosition(_rng_hgt_innov,rng_hgt_innov_gate,
|
|
rng_hgt_obs_var, _rng_hgt_innov_var,_rng_hgt_test_ratio);
|
|
|
|
} else if (_control_status.flags.ev_hgt) {
|
|
Vector2f ev_hgt_innov_gate;
|
|
Vector3f ev_hgt_obs_var;
|
|
// calculate the innovation assuming the external vision observation is in local NED frame
|
|
_ev_pos_innov(2) = _state.pos(2) - _ev_sample_delayed.pos(2);
|
|
// observation variance - defined externally
|
|
ev_hgt_obs_var(2) = fmaxf(_ev_sample_delayed.posVar(2), sq(0.01f));
|
|
// innovation gate size
|
|
ev_hgt_innov_gate(1) = fmaxf(_params.ev_pos_innov_gate, 1.0f);
|
|
// fuse height information
|
|
fuseVerticalPosition(_ev_pos_innov,ev_hgt_innov_gate,
|
|
ev_hgt_obs_var, _ev_pos_innov_var,_ev_pos_test_ratio);
|
|
}
|
|
}
|
|
}
|
|
|
|
void Ekf::checkRangeAidSuitability()
|
|
{
|
|
if (_control_status.flags.in_air
|
|
&& _range_sensor.isHealthy()
|
|
&& isTerrainEstimateValid()
|
|
&& isHorizontalAidingActive()) {
|
|
// check if we can use range finder measurements to estimate height, use hysteresis to avoid rapid switching
|
|
// Note that the 0.7 coefficients and the innovation check are arbitrary values but work well in practice
|
|
const bool is_in_range = _is_range_aid_suitable
|
|
? (_terrain_vpos - _state.pos(2) < _params.max_hagl_for_range_aid)
|
|
: (_terrain_vpos - _state.pos(2) < _params.max_hagl_for_range_aid * 0.7f);
|
|
|
|
const float ground_vel = sqrtf(_state.vel(0) * _state.vel(0) + _state.vel(1) * _state.vel(1));
|
|
const bool is_below_max_speed = _is_range_aid_suitable
|
|
? ground_vel < _params.max_vel_for_range_aid
|
|
: ground_vel < _params.max_vel_for_range_aid * 0.7f;
|
|
|
|
const bool is_hagl_stable = _is_range_aid_suitable
|
|
? ((_hagl_innov * _hagl_innov / (sq(_params.range_aid_innov_gate) * _hagl_innov_var)) < 1.0f)
|
|
: ((_hagl_innov * _hagl_innov / (sq(_params.range_aid_innov_gate) * _hagl_innov_var)) < 0.01f);
|
|
|
|
_is_range_aid_suitable = is_in_range && is_below_max_speed && is_hagl_stable;
|
|
|
|
} else {
|
|
_is_range_aid_suitable = false;
|
|
}
|
|
}
|
|
|
|
void Ekf::controlAirDataFusion()
|
|
{
|
|
// control activation and initialisation/reset of wind states required for airspeed fusion
|
|
|
|
// If both airspeed and sideslip fusion have timed out and we are not using a drag observation model then we no longer have valid wind estimates
|
|
const bool airspeed_timed_out = isTimedOut(_time_last_arsp_fuse, (uint64_t)10e6);
|
|
const bool sideslip_timed_out = isTimedOut(_time_last_beta_fuse, (uint64_t)10e6);
|
|
|
|
if (_control_status.flags.wind && airspeed_timed_out && sideslip_timed_out && !(_params.fusion_mode & MASK_USE_DRAG)) {
|
|
_control_status.flags.wind = false;
|
|
}
|
|
|
|
if (_control_status.flags.fuse_aspd && airspeed_timed_out) {
|
|
_control_status.flags.fuse_aspd = false;
|
|
}
|
|
|
|
// Always try to fuse airspeed data if available and we are in flight
|
|
if (_tas_data_ready && _control_status.flags.in_air) {
|
|
// always fuse airsped data if we are flying and data is present
|
|
if (!_control_status.flags.fuse_aspd) {
|
|
_control_status.flags.fuse_aspd = true;
|
|
}
|
|
|
|
// If starting wind state estimation, reset the wind states and covariances before fusing any data
|
|
if (!_control_status.flags.wind) {
|
|
// activate the wind states
|
|
_control_status.flags.wind = true;
|
|
// reset the timout timer to prevent repeated resets
|
|
_time_last_arsp_fuse = _time_last_imu;
|
|
_time_last_beta_fuse = _time_last_imu;
|
|
// reset the wind speed states and corresponding covariances
|
|
resetWindStates();
|
|
resetWindCovariance();
|
|
}
|
|
|
|
fuseAirspeed();
|
|
}
|
|
}
|
|
|
|
void Ekf::controlBetaFusion()
|
|
{
|
|
// control activation and initialisation/reset of wind states required for synthetic sideslip fusion fusion
|
|
|
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// If both airspeed and sideslip fusion have timed out and we are not using a drag observation model then we no longer have valid wind estimates
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const bool sideslip_timed_out = isTimedOut(_time_last_beta_fuse, (uint64_t)10e6);
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const bool airspeed_timed_out = isTimedOut(_time_last_arsp_fuse, (uint64_t)10e6);
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if (_control_status.flags.wind && airspeed_timed_out && sideslip_timed_out && !(_params.fusion_mode & MASK_USE_DRAG)) {
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_control_status.flags.wind = false;
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}
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// Perform synthetic sideslip fusion when in-air and sideslip fuson had been enabled externally in addition to the following criteria:
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// Sufficient time has lapsed sice the last fusion
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bool beta_fusion_time_triggered = isTimedOut(_time_last_beta_fuse, _params.beta_avg_ft_us);
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if (beta_fusion_time_triggered && _control_status.flags.fuse_beta && _control_status.flags.in_air) {
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// If starting wind state estimation, reset the wind states and covariances before fusing any data
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if (!_control_status.flags.wind) {
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// activate the wind states
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_control_status.flags.wind = true;
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// reset the timeout timers to prevent repeated resets
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_time_last_beta_fuse = _time_last_imu;
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_time_last_arsp_fuse = _time_last_imu;
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// reset the wind speed states and corresponding covariances
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resetWindStates();
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resetWindCovariance();
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}
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fuseSideslip();
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}
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}
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void Ekf::controlDragFusion()
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{
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if (_params.fusion_mode & MASK_USE_DRAG) {
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if (_control_status.flags.in_air
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&& !_mag_inhibit_yaw_reset_req) {
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if (!_control_status.flags.wind) {
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// reset the wind states and covariances when starting drag accel fusion
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_control_status.flags.wind = true;
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resetWindStates();
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resetWindCovariance();
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|
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} else if (_drag_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_drag_sample_delayed)) {
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fuseDrag();
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}
|
|
|
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} else {
|
|
_control_status.flags.wind = false;
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}
|
|
}
|
|
}
|
|
|
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void Ekf::controlFakePosFusion()
|
|
{
|
|
// if we aren't doing any aiding, fake position measurements at the last known position to constrain drift
|
|
// Coincide fake measurements with baro data for efficiency with a minimum fusion rate of 5Hz
|
|
|
|
if (!isHorizontalAidingActive()
|
|
&& !(_control_status.flags.fuse_aspd && _control_status.flags.fuse_beta)) {
|
|
|
|
// We now need to use a synthetic position observation to prevent unconstrained drift of the INS states.
|
|
_using_synthetic_position = true;
|
|
|
|
// Fuse synthetic position observations every 200msec
|
|
if (isTimedOut(_time_last_fake_pos, (uint64_t)2e5)) {
|
|
|
|
Vector3f fake_pos_obs_var;
|
|
|
|
// Reset position and velocity states if we re-commence this aiding method
|
|
if (isTimedOut(_time_last_fake_pos, (uint64_t)4e5)) {
|
|
resetHorizontalPosition();
|
|
resetVelocity();
|
|
_fuse_hpos_as_odom = false;
|
|
|
|
if (_time_last_fake_pos != 0) {
|
|
ECL_WARN_TIMESTAMPED("stopping navigation");
|
|
}
|
|
|
|
}
|
|
_time_last_fake_pos = _time_last_imu;
|
|
|
|
if (_control_status.flags.in_air && _control_status.flags.tilt_align) {
|
|
fake_pos_obs_var(0) = fake_pos_obs_var(1) = sq(fmaxf(_params.pos_noaid_noise, _params.gps_pos_noise));
|
|
|
|
} else {
|
|
fake_pos_obs_var(0) = fake_pos_obs_var(1) = sq(0.5f);
|
|
}
|
|
|
|
_gps_pos_innov.xy() = Vector2f(_state.pos) - _last_known_posNE;
|
|
|
|
// glitch protection is not required so set gate to a large value
|
|
const Vector2f fake_pos_innov_gate(100.0f, 100.0f);
|
|
|
|
fuseHorizontalPosition(_gps_pos_innov, fake_pos_innov_gate, fake_pos_obs_var,
|
|
_gps_pos_innov_var, _gps_pos_test_ratio);
|
|
}
|
|
|
|
} else {
|
|
_using_synthetic_position = false;
|
|
}
|
|
|
|
}
|
|
|
|
void Ekf::controlAuxVelFusion()
|
|
{
|
|
const bool data_ready = _auxvel_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_auxvel_sample_delayed);
|
|
|
|
if (data_ready && isHorizontalAidingActive()) {
|
|
|
|
const Vector2f aux_vel_innov_gate(_params.auxvel_gate, _params.auxvel_gate);
|
|
|
|
_aux_vel_innov = _state.vel - _auxvel_sample_delayed.vel;
|
|
|
|
fuseHorizontalVelocity(_aux_vel_innov, aux_vel_innov_gate, _auxvel_sample_delayed.velVar,
|
|
_aux_vel_innov_var, _aux_vel_test_ratio);
|
|
|
|
// Can be enabled after bit for this is added to EKF_AID_MASK
|
|
// fuseVerticalVelocity(_aux_vel_innov, aux_vel_innov_gate, _auxvel_sample_delayed.velVar,
|
|
// _aux_vel_innov_var, _aux_vel_test_ratio);
|
|
|
|
}
|
|
}
|