ekf2: add OF estimator aid src status

2026-10-23 03:33:34 +08:00 · 2022-10-18 14:19:16 -04:00
parent 75c63aee2a
commit 535415a537
15 changed files with 471 additions and 377 deletions
@@ -0,0 +1,230 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2022 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 optical_flow_control.cpp
+ * Control functions for optical flow fusion
+ */
+
+#include "ekf.h"
+
+void Ekf::controlOpticalFlowFusion()
+{
+	// Check if on ground motion is un-suitable for use of optical flow
+	if (!_control_status.flags.in_air) {
+		updateOnGroundMotionForOpticalFlowChecks();
+
+	} else {
+		resetOnGroundMotionForOpticalFlowChecks();
+	}
+
+	// Accumulate autopilot gyro data across the same time interval as the flow sensor
+	const Vector3f delta_angle(_imu_sample_delayed.delta_ang - (getGyroBias() * _imu_sample_delayed.delta_ang_dt));
+	if (_delta_time_of < 0.1f) {
+		_imu_del_ang_of += delta_angle;
+		_delta_time_of += _imu_sample_delayed.delta_ang_dt;
+
+	} else {
+		// reset the accumulators if the time interval is too large
+		_imu_del_ang_of = delta_angle;
+		_delta_time_of = _imu_sample_delayed.delta_ang_dt;
+	}
+
+	if (_flow_data_ready) {
+		const bool is_quality_good = (_flow_sample_delayed.quality >= _params.flow_qual_min);
+		const bool is_magnitude_good = !_flow_sample_delayed.flow_xy_rad.longerThan(_flow_sample_delayed.dt * _flow_max_rate);
+		const bool is_tilt_good = (_R_to_earth(2, 2) > _params.range_cos_max_tilt);
+
+		const float delta_time_min = fmaxf(0.7f * _delta_time_of, 0.001f);
+		const float delta_time_max = fminf(1.3f * _delta_time_of, 0.2f);
+		bool is_delta_time_good = _flow_sample_delayed.dt >= delta_time_min && _flow_sample_delayed.dt <= delta_time_max;
+
+		if (!is_delta_time_good && (_flow_sample_delayed.dt > FLT_EPSILON)) {
+
+			if (fabsf(_imu_sample_delayed.delta_ang_dt - _flow_sample_delayed.dt) < 0.1f) {
+				// reset accumulators to current IMU
+				_imu_del_ang_of = delta_angle;
+				_delta_time_of = _imu_sample_delayed.delta_ang_dt;
+
+				is_delta_time_good = true;
+			 }
+
+			if (is_quality_good && !is_delta_time_good) {
+				ECL_DEBUG("Optical flow: bad delta time: OF dt %.6f s (min: %.3f, max: %.3f), IMU dt %.6f s",
+					(double)_flow_sample_delayed.dt, (double)delta_time_min, (double)delta_time_max, (double)_imu_sample_delayed.delta_ang_dt);
+			}
+		}
+
+		const bool is_body_rate_comp_available = calcOptFlowBodyRateComp();
+
+		// don't allow invalid flow gyro_xyz to propagate
+		if (!PX4_ISFINITE(_flow_sample_delayed.gyro_xyz(0)) || !PX4_ISFINITE(_flow_sample_delayed.gyro_xyz(1)) || !PX4_ISFINITE(_flow_sample_delayed.gyro_xyz(2))) {
+
+			_flow_sample_delayed.gyro_xyz.zero();
+		}
+
+		if (is_quality_good
+		    && is_magnitude_good
+		    && is_tilt_good
+		    && is_body_rate_comp_available
+		    && is_delta_time_good) {
+			// 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 if (!_control_status.flags.in_air) {
+
+			if (!is_delta_time_good) {
+				// handle special case of SITL and PX4Flow where dt is forced to
+				// zero when the quaity is 0
+				_flow_sample_delayed.dt = delta_time_min;
+			}
+
+			// when on the ground with poor flow quality,
+			// assume zero ground relative velocity and LOS rate
+			_flow_compensated_XY_rad.setZero();
+
+		} else {
+			// don't use this flow data and wait for the next data to arrive
+			_flow_data_ready = false;
+			_flow_compensated_XY_rad.setZero();
+		}
+
+		updateOptFlow(_aid_src_optical_flow);
+
+	} else {
+		_flow_compensated_XY_rad.setZero();
+	}
+
+	// New optical flow data is available and is ready to be fused when the midpoint of the sample falls behind the fusion time horizon
+	if (_flow_data_ready) {
+
+		// Inhibit flow use if motion is un-suitable or we have good quality GPS
+		// Apply hysteresis to prevent rapid mode switching
+		const float gps_err_norm_lim = _control_status.flags.opt_flow ? 0.7f : 1.0f;
+
+		// Check if we are in-air and require optical flow to control position drift
+		const bool is_flow_required = _control_status.flags.in_air
+					      && (_control_status.flags.inertial_dead_reckoning // is doing inertial dead-reckoning so must constrain drift urgently
+						  || isOnlyActiveSourceOfHorizontalAiding(_control_status.flags.opt_flow)
+						  || (_control_status.flags.gps && (_gps_error_norm > gps_err_norm_lim))); // is using GPS, but GPS is bad
+
+		// inhibit use of optical flow if motion is unsuitable and we are not reliant on it for flight navigation
+		const bool preflight_motion_not_ok = !_control_status.flags.in_air
+						     && ((_imu_sample_delayed.time_us > (_time_good_motion_us + (uint64_t)1E5))
+								     || (_imu_sample_delayed.time_us < (_time_bad_motion_us + (uint64_t)5E6)));
+		const bool flight_condition_not_ok = _control_status.flags.in_air && !isTerrainEstimateValid();
+
+		const bool inhibit_flow_use = ((preflight_motion_not_ok || flight_condition_not_ok) && !is_flow_required)
+				    || !_control_status.flags.tilt_align;
+
+		// Handle cases where we are using optical flow but we should not use it anymore
+		if (_control_status.flags.opt_flow) {
+			if (!(_params.fusion_mode & SensorFusionMask::USE_OPT_FLOW)
+			    || inhibit_flow_use) {
+
+				stopFlowFusion();
+				return;
+			}
+		}
+
+		// optical flow fusion mode selection logic
+		if ((_params.fusion_mode & SensorFusionMask::USE_OPT_FLOW) // optical flow has been selected by the user
+		    && !_control_status.flags.opt_flow // we are not yet using flow data
+		    && !inhibit_flow_use) {
+
+			// set the flag and reset the fusion timeout
+			ECL_INFO("starting optical flow fusion");
+
+			// if we are not using GPS or external vision aiding, then the velocity and position states and covariances need to be set
+			if (!isHorizontalAidingActive()) {
+				resetHorizontalVelocityToOpticalFlow(_flow_sample_delayed);
+				resetHorizontalPositionToOpticalFlow();
+			}
+
+			_control_status.flags.opt_flow = true;
+			_aid_src_optical_flow.time_last_fuse = _imu_sample_delayed.time_us;
+
+			return;
+		}
+
+		if (_control_status.flags.opt_flow) {
+			// Wait until the midpoint of the flow sample has fallen behind the fusion time horizon
+			if (_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 (isRecent(_time_last_hagl_fuse, (uint64_t)10e6)) {
+					fuseOptFlow();
+					_last_known_pos.xy() = _state.pos.xy();
+				}
+
+				_flow_data_ready = false;
+			}
+
+			// handle the case when we have optical flow, are reliant on it, but have not been using it for an extended period
+			if (isTimedOut(_aid_src_optical_flow.time_last_fuse, _params.reset_timeout_max)
+			    && !isOtherSourceOfHorizontalAidingThan(_control_status.flags.opt_flow)) {
+
+				resetHorizontalVelocityToOpticalFlow(_flow_sample_delayed);
+				resetHorizontalPositionToOpticalFlow();
+			}
+		}
+
+	} else if (_control_status.flags.opt_flow && !isRecent(_flow_sample_delayed.time_us, (uint64_t)10e6)) {
+
+		stopFlowFusion();
+	}
+}
+
+void Ekf::updateOnGroundMotionForOpticalFlowChecks()
+{
+	// When on ground check if the vehicle is being shaken or moved in a way that could cause a loss of navigation
+	const float accel_norm = _accel_vec_filt.norm();
+
+	const bool motion_is_excessive = ((accel_norm > (CONSTANTS_ONE_G * 1.5f)) // upper g limit
+					  || (accel_norm < (CONSTANTS_ONE_G * 0.5f)) // lower g limit
+					  || (_ang_rate_magnitude_filt > _flow_max_rate) // angular rate exceeds flow sensor limit
+					  || (_R_to_earth(2, 2) < cosf(math::radians(30.0f)))); // tilted excessively
+
+	if (motion_is_excessive) {
+		_time_bad_motion_us = _imu_sample_delayed.time_us;
+
+	} else {
+		_time_good_motion_us = _imu_sample_delayed.time_us;
+	}
+}
+
+void Ekf::resetOnGroundMotionForOpticalFlowChecks()
+{
+	_time_bad_motion_us = 0;
+	_time_good_motion_us = _imu_sample_delayed.time_us;
+}