From 904bf8ef9fa42003fa13e6a645cfa95a754f3e36 Mon Sep 17 00:00:00 2001 From: bresch Date: Tue, 15 Mar 2022 17:10:25 +0100 Subject: [PATCH] ekf: add range finder kinematic consistency check At each new valid range measurement, the time derivative of the distance to the ground is computed and compared with the estimated velocity. The average of a normalized innovation squared statistic check is used to detect a bias in the derivative of distance measurement, indicating that the distance measurements are kinematically inconsistent with the filter. --- src/modules/ekf2/CMakeLists.txt | 1 + src/modules/ekf2/EKF/CMakeLists.txt | 1 + src/modules/ekf2/EKF/control.cpp | 1 + src/modules/ekf2/EKF/estimator_interface.h | 3 + .../EKF/range_finder_consistency_check.cpp | 64 ++++++++++++++++++ .../EKF/range_finder_consistency_check.hpp | 66 +++++++++++++++++++ 6 files changed, 136 insertions(+) create mode 100644 src/modules/ekf2/EKF/range_finder_consistency_check.cpp create mode 100644 src/modules/ekf2/EKF/range_finder_consistency_check.hpp diff --git a/src/modules/ekf2/CMakeLists.txt b/src/modules/ekf2/CMakeLists.txt index e47d1f2f60..7fdf48dfaf 100644 --- a/src/modules/ekf2/CMakeLists.txt +++ b/src/modules/ekf2/CMakeLists.txt @@ -66,6 +66,7 @@ px4_add_module( EKF/mag_control.cpp EKF/mag_fusion.cpp EKF/optflow_fusion.cpp + EKF/range_finder_consistency_check.cpp EKF/sensor_range_finder.cpp EKF/sideslip_fusion.cpp EKF/terrain_estimator.cpp diff --git a/src/modules/ekf2/EKF/CMakeLists.txt b/src/modules/ekf2/EKF/CMakeLists.txt index 745317d132..3fce773cb0 100644 --- a/src/modules/ekf2/EKF/CMakeLists.txt +++ b/src/modules/ekf2/EKF/CMakeLists.txt @@ -51,6 +51,7 @@ add_library(ecl_EKF mag_control.cpp mag_fusion.cpp optflow_fusion.cpp + range_finder_consistency_check.cpp sensor_range_finder.cpp sideslip_fusion.cpp terrain_estimator.cpp diff --git a/src/modules/ekf2/EKF/control.cpp b/src/modules/ekf2/EKF/control.cpp index 7771b669d4..f36872f28c 100644 --- a/src/modules/ekf2/EKF/control.cpp +++ b/src/modules/ekf2/EKF/control.cpp @@ -140,6 +140,7 @@ void Ekf::controlFusionModes() const Vector3f pos_offset_body = _params.rng_pos_body - _params.imu_pos_body; const Vector3f pos_offset_earth = _R_to_earth * pos_offset_body; _range_sensor.setRange(_range_sensor.getRange() + pos_offset_earth(2) / _range_sensor.getCosTilt()); + _rng_consistency_check.update(_range_sensor.getDistBottom(), getRngHeightVariance(), _state.vel(2), P(6, 6), static_cast(_time_last_imu) * 1e-6f); } } diff --git a/src/modules/ekf2/EKF/estimator_interface.h b/src/modules/ekf2/EKF/estimator_interface.h index c22065be75..328c5fd537 100644 --- a/src/modules/ekf2/EKF/estimator_interface.h +++ b/src/modules/ekf2/EKF/estimator_interface.h @@ -63,6 +63,7 @@ #include "common.h" #include "RingBuffer.h" #include "imu_down_sampler.hpp" +#include "range_finder_consistency_check.hpp" #include "sensor_range_finder.hpp" #include "utils.hpp" @@ -297,6 +298,8 @@ protected: extVisionSample _ev_sample_delayed_prev{}; dragSample _drag_down_sampled{}; // down sampled drag specific force data (filter prediction rate -> observation rate) + RangeFinderConsistencyCheck _rng_consistency_check; + float _air_density{CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C}; // air density (kg/m**3) // Sensor limitations diff --git a/src/modules/ekf2/EKF/range_finder_consistency_check.cpp b/src/modules/ekf2/EKF/range_finder_consistency_check.cpp new file mode 100644 index 0000000000..37a27bfcfa --- /dev/null +++ b/src/modules/ekf2/EKF/range_finder_consistency_check.cpp @@ -0,0 +1,64 @@ +/**************************************************************************** + * + * Copyright (c) 2022 PX4. 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 range_finder_consistency_check.cpp + */ + +#include "range_finder_consistency_check.hpp" + +void RangeFinderConsistencyCheck::update(float dist_bottom, float dist_bottom_var, float vz, float vz_var, float time_s) +{ + const float dt = time_s - _time_last_update_s; + + if ((_time_last_update_s < FLT_EPSILON) + || (dt < 0.001f) || (dt > 0.5f)) { + _time_last_update_s = time_s; + _dist_bottom_prev = dist_bottom; + return; + } + + const float vel_bottom = (dist_bottom - _dist_bottom_prev) / dt; + const float innov = -vel_bottom - vz; // vel_bottom is +up while vz is +down + const float vel_bottom_var = 2.f * dist_bottom_var / (dt * dt); + const float innov_var = vel_bottom_var + vz_var; + const float normalized_innov_sq = (innov * innov) / innov_var; + _vel_bottom_test_ratio = normalized_innov_sq / (_vel_bottom_gate * _vel_bottom_gate); + + _vel_bottom_signed_test_ratio_lpf.setParameters(dt, _vel_bottom_signed_test_ratio_tau); + const float signed_test_ratio = matrix::sign(innov) * normalized_innov_sq / (_vel_bottom_signed_gate * _vel_bottom_signed_gate); + _vel_bottom_signed_test_ratio_lpf.update(signed_test_ratio); + + _time_last_update_s = time_s; + _dist_bottom_prev = dist_bottom; +} diff --git a/src/modules/ekf2/EKF/range_finder_consistency_check.hpp b/src/modules/ekf2/EKF/range_finder_consistency_check.hpp new file mode 100644 index 0000000000..f041d66dbd --- /dev/null +++ b/src/modules/ekf2/EKF/range_finder_consistency_check.hpp @@ -0,0 +1,66 @@ +/**************************************************************************** + * + * Copyright (c) 2022 PX4. 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 range_finder_consistency_check.hpp + * @brief Compute statistical tests of the range finder data + * using the estimated velocity as a reference in order to detect sensor faults + */ + +#pragma once + +#include + +class RangeFinderConsistencyCheck final +{ +public: + RangeFinderConsistencyCheck() = default; + ~RangeFinderConsistencyCheck() = default; + + void update(float dist_bottom, float dist_bottom_var, float vz, float vz_var, float time_s); + + float getTestRatio() const { return _vel_bottom_test_ratio; } + float getSignedTestRatioLpf() const { return _vel_bottom_signed_test_ratio_lpf.getState(); } + bool isKinematicallyConsistent() const { return _vel_bottom_signed_test_ratio_lpf.getState() < 1.f; } + +private: + float _time_last_update_s{}; + float _dist_bottom_prev{}; + + float _vel_bottom_test_ratio{}; + AlphaFilter _vel_bottom_signed_test_ratio_lpf{}; // average signed test ratio used to detect a bias in the data + + static constexpr float _vel_bottom_signed_test_ratio_tau = 2.f; + static constexpr float _vel_bottom_gate = 3.f; + static constexpr float _vel_bottom_signed_gate = 0.1f; +};