/**************************************************************************** * * Copyright (c) 2015 Estimation and Control Library (ECL). 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 ECL 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 drag_fusion.cpp * Body frame drag fusion methods used for multi-rotor wind estimation. * equations generated using EKF/python/ekf_derivation/main.py * * @author Paul Riseborough * */ #include "ekf.h" #include #include void Ekf::fuseDrag() { SparseVector24f<0,1,2,3,4,5,6,22,23> Hfusion; // Observation Jacobians Vector24f Kfusion; // Kalman gain vector const float R_ACC = fmaxf(_params.drag_noise, 0.5f); // observation noise variance in specific force drag (m/sec**2)**2 const float rho = fmaxf(_air_density, 0.1f); // air density (kg/m**3) // calculate inverse of ballistic coefficient if (_params.bcoef_x < 1.0f || _params.bcoef_y < 1.0f) { return; } const Vector2f ballistic_coef_inv_xy(1.f / _params.bcoef_x, 1.f / _params.bcoef_y); // get latest estimated orientation const float &q0 = _state.quat_nominal(0); const float &q1 = _state.quat_nominal(1); const float &q2 = _state.quat_nominal(2); const float &q3 = _state.quat_nominal(3); // get latest velocity in earth frame const float &vn = _state.vel(0); const float &ve = _state.vel(1); const float &vd = _state.vel(2); // get latest wind velocity in earth frame const float &vwn = _state.wind_vel(0); const float &vwe = _state.wind_vel(1); // predicted specific forces // calculate relative wind velocity in earth frame and rotate into body frame const Vector3f rel_wind_earth(vn - vwn, ve - vwe, vd); const Dcmf earth_to_body = quatToInverseRotMat(_state.quat_nominal); const Vector3f rel_wind_body = earth_to_body * rel_wind_earth; // perform sequential fusion of XY specific forces for (uint8_t axis_index = 0; axis_index < 2; axis_index++) { // Estimate the airspeed from the measured drag force and ballistic coefficient const float mea_acc = _drag_sample_delayed.accelXY(axis_index) - _state.delta_vel_bias(axis_index) / _dt_ekf_avg; const float airSpd = sqrtf((2.0f * fabsf(mea_acc)) / (ballistic_coef_inv_xy(axis_index) * rho)); // Estimate the derivative of specific force wrt airspeed along the X axis // Limit lower value to prevent arithmetic exceptions const float Kacc = fmaxf(1e-1f, rho * ballistic_coef_inv_xy(axis_index) * airSpd); if (axis_index == 0) { // intermediate variables const float HK0 = vn - vwn; const float HK1 = ve - vwe; const float HK2 = HK0*q0 + HK1*q3 - q2*vd; const float HK3 = 2*Kacc; const float HK4 = HK0*q1 + HK1*q2 + q3*vd; const float HK5 = HK0*q2 - HK1*q1 + q0*vd; const float HK6 = -HK0*q3 + HK1*q0 + q1*vd; const float HK7 = ecl::powf(q0, 2) + ecl::powf(q1, 2) - ecl::powf(q2, 2) - ecl::powf(q3, 2); const float HK8 = HK7*Kacc; const float HK9 = q0*q3 + q1*q2; const float HK10 = HK3*HK9; const float HK11 = q0*q2 - q1*q3; const float HK12 = 2*HK9; const float HK13 = 2*HK11; const float HK14 = 2*HK4; const float HK15 = 2*HK2; const float HK16 = 2*HK5; const float HK17 = 2*HK6; const float HK18 = -HK12*P(0,23) + HK12*P(0,5) - HK13*P(0,6) + HK14*P(0,1) + HK15*P(0,0) - HK16*P(0,2) + HK17*P(0,3) - HK7*P(0,22) + HK7*P(0,4); const float HK19 = HK12*P(5,23); const float HK20 = -HK12*P(23,23) - HK13*P(6,23) + HK14*P(1,23) + HK15*P(0,23) - HK16*P(2,23) + HK17*P(3,23) + HK19 - HK7*P(22,23) + HK7*P(4,23); const float HK21 = ecl::powf(Kacc, 2); const float HK22 = HK12*HK21; const float HK23 = HK12*P(5,5) - HK13*P(5,6) + HK14*P(1,5) + HK15*P(0,5) - HK16*P(2,5) + HK17*P(3,5) - HK19 + HK7*P(4,5) - HK7*P(5,22); const float HK24 = HK12*P(5,6) - HK12*P(6,23) - HK13*P(6,6) + HK14*P(1,6) + HK15*P(0,6) - HK16*P(2,6) + HK17*P(3,6) + HK7*P(4,6) - HK7*P(6,22); const float HK25 = HK7*P(4,22); const float HK26 = -HK12*P(4,23) + HK12*P(4,5) - HK13*P(4,6) + HK14*P(1,4) + HK15*P(0,4) - HK16*P(2,4) + HK17*P(3,4) - HK25 + HK7*P(4,4); const float HK27 = HK21*HK7; const float HK28 = -HK12*P(22,23) + HK12*P(5,22) - HK13*P(6,22) + HK14*P(1,22) + HK15*P(0,22) - HK16*P(2,22) + HK17*P(3,22) + HK25 - HK7*P(22,22); const float HK29 = -HK12*P(1,23) + HK12*P(1,5) - HK13*P(1,6) + HK14*P(1,1) + HK15*P(0,1) - HK16*P(1,2) + HK17*P(1,3) - HK7*P(1,22) + HK7*P(1,4); const float HK30 = -HK12*P(2,23) + HK12*P(2,5) - HK13*P(2,6) + HK14*P(1,2) + HK15*P(0,2) - HK16*P(2,2) + HK17*P(2,3) - HK7*P(2,22) + HK7*P(2,4); const float HK31 = -HK12*P(3,23) + HK12*P(3,5) - HK13*P(3,6) + HK14*P(1,3) + HK15*P(0,3) - HK16*P(2,3) + HK17*P(3,3) - HK7*P(3,22) + HK7*P(3,4); //const float HK32 = Kacc/(-HK13*HK21*HK24 + HK14*HK21*HK29 + HK15*HK18*HK21 - HK16*HK21*HK30 + HK17*HK21*HK31 - HK20*HK22 + HK22*HK23 + HK26*HK27 - HK27*HK28 + R_ACC); // calculate innovation variance and exit if badly conditioned _drag_innov_var(0) = (-HK13*HK21*HK24 + HK14*HK21*HK29 + HK15*HK18*HK21 - HK16*HK21*HK30 + HK17*HK21*HK31 - HK20*HK22 + HK22*HK23 + HK26*HK27 - HK27*HK28 + R_ACC); if (_drag_innov_var(0) < R_ACC) { return; } const float HK32 = Kacc / _drag_innov_var(0); // Observation Jacobians Hfusion.at<0>() = -HK2*HK3; Hfusion.at<1>() = -HK3*HK4; Hfusion.at<2>() = HK3*HK5; Hfusion.at<3>() = -HK3*HK6; Hfusion.at<4>() = -HK8; Hfusion.at<5>() = -HK10; Hfusion.at<6>() = HK11*HK3; Hfusion.at<22>() = HK8; Hfusion.at<23>() = HK10; // Kalman gains // Don't allow modification of any states other than wind velocity at this stage of development - we only need a wind estimate. // Kfusion(0) = -HK18*HK32; // Kfusion(1) = -HK29*HK32; // Kfusion(2) = -HK30*HK32; // Kfusion(3) = -HK31*HK32; // Kfusion(4) = -HK26*HK32; // Kfusion(5) = -HK23*HK32; // Kfusion(6) = -HK24*HK32; // Kfusion(7) = -HK32*(HK12*P(5,7) - HK12*P(7,23) - HK13*P(6,7) + HK14*P(1,7) + HK15*P(0,7) - HK16*P(2,7) + HK17*P(3,7) + HK7*P(4,7) - HK7*P(7,22)); // Kfusion(8) = -HK32*(HK12*P(5,8) - HK12*P(8,23) - HK13*P(6,8) + HK14*P(1,8) + HK15*P(0,8) - HK16*P(2,8) + HK17*P(3,8) + HK7*P(4,8) - HK7*P(8,22)); // Kfusion(9) = -HK32*(HK12*P(5,9) - HK12*P(9,23) - HK13*P(6,9) + HK14*P(1,9) + HK15*P(0,9) - HK16*P(2,9) + HK17*P(3,9) + HK7*P(4,9) - HK7*P(9,22)); // Kfusion(10) = -HK32*(-HK12*P(10,23) + HK12*P(5,10) - HK13*P(6,10) + HK14*P(1,10) + HK15*P(0,10) - HK16*P(2,10) + HK17*P(3,10) - HK7*P(10,22) + HK7*P(4,10)); // Kfusion(11) = -HK32*(-HK12*P(11,23) + HK12*P(5,11) - HK13*P(6,11) + HK14*P(1,11) + HK15*P(0,11) - HK16*P(2,11) + HK17*P(3,11) - HK7*P(11,22) + HK7*P(4,11)); // Kfusion(12) = -HK32*(-HK12*P(12,23) + HK12*P(5,12) - HK13*P(6,12) + HK14*P(1,12) + HK15*P(0,12) - HK16*P(2,12) + HK17*P(3,12) - HK7*P(12,22) + HK7*P(4,12)); // Kfusion(13) = -HK32*(-HK12*P(13,23) + HK12*P(5,13) - HK13*P(6,13) + HK14*P(1,13) + HK15*P(0,13) - HK16*P(2,13) + HK17*P(3,13) - HK7*P(13,22) + HK7*P(4,13)); // Kfusion(14) = -HK32*(-HK12*P(14,23) + HK12*P(5,14) - HK13*P(6,14) + HK14*P(1,14) + HK15*P(0,14) - HK16*P(2,14) + HK17*P(3,14) - HK7*P(14,22) + HK7*P(4,14)); // Kfusion(15) = -HK32*(-HK12*P(15,23) + HK12*P(5,15) - HK13*P(6,15) + HK14*P(1,15) + HK15*P(0,15) - HK16*P(2,15) + HK17*P(3,15) - HK7*P(15,22) + HK7*P(4,15)); // Kfusion(16) = -HK32*(-HK12*P(16,23) + HK12*P(5,16) - HK13*P(6,16) + HK14*P(1,16) + HK15*P(0,16) - HK16*P(2,16) + HK17*P(3,16) - HK7*P(16,22) + HK7*P(4,16)); // Kfusion(17) = -HK32*(-HK12*P(17,23) + HK12*P(5,17) - HK13*P(6,17) + HK14*P(1,17) + HK15*P(0,17) - HK16*P(2,17) + HK17*P(3,17) - HK7*P(17,22) + HK7*P(4,17)); // Kfusion(18) = -HK32*(-HK12*P(18,23) + HK12*P(5,18) - HK13*P(6,18) + HK14*P(1,18) + HK15*P(0,18) - HK16*P(2,18) + HK17*P(3,18) - HK7*P(18,22) + HK7*P(4,18)); // Kfusion(19) = -HK32*(-HK12*P(19,23) + HK12*P(5,19) - HK13*P(6,19) + HK14*P(1,19) + HK15*P(0,19) - HK16*P(2,19) + HK17*P(3,19) - HK7*P(19,22) + HK7*P(4,19)); // Kfusion(20) = -HK32*(-HK12*P(20,23) + HK12*P(5,20) - HK13*P(6,20) + HK14*P(1,20) + HK15*P(0,20) - HK16*P(2,20) + HK17*P(3,20) - HK7*P(20,22) + HK7*P(4,20)); // Kfusion(21) = -HK32*(-HK12*P(21,23) + HK12*P(5,21) - HK13*P(6,21) + HK14*P(1,21) + HK15*P(0,21) - HK16*P(2,21) + HK17*P(3,21) - HK7*P(21,22) + HK7*P(4,21)); Kfusion(22) = -HK28*HK32; Kfusion(23) = -HK20*HK32; } else if (axis_index == 1) { // intermediate variables const float HK0 = ve - vwe; const float HK1 = vn - vwn; const float HK2 = HK0*q0 - HK1*q3 + q1*vd; const float HK3 = 2*Kacc; const float HK4 = -HK0*q1 + HK1*q2 + q0*vd; const float HK5 = HK0*q2 + HK1*q1 + q3*vd; const float HK6 = HK0*q3 + HK1*q0 - q2*vd; const float HK7 = q0*q3 - q1*q2; const float HK8 = HK3*HK7; const float HK9 = ecl::powf(q0, 2) - ecl::powf(q1, 2) + ecl::powf(q2, 2) - ecl::powf(q3, 2); const float HK10 = HK9*Kacc; const float HK11 = q0*q1 + q2*q3; const float HK12 = 2*HK11; const float HK13 = 2*HK7; const float HK14 = 2*HK5; const float HK15 = 2*HK2; const float HK16 = 2*HK4; const float HK17 = 2*HK6; const float HK18 = HK12*P(0,6) + HK13*P(0,22) - HK13*P(0,4) + HK14*P(0,2) + HK15*P(0,0) + HK16*P(0,1) - HK17*P(0,3) - HK9*P(0,23) + HK9*P(0,5); const float HK19 = ecl::powf(Kacc, 2); const float HK20 = HK12*P(6,6) - HK13*P(4,6) + HK13*P(6,22) + HK14*P(2,6) + HK15*P(0,6) + HK16*P(1,6) - HK17*P(3,6) + HK9*P(5,6) - HK9*P(6,23); const float HK21 = HK13*P(4,22); const float HK22 = HK12*P(6,22) + HK13*P(22,22) + HK14*P(2,22) + HK15*P(0,22) + HK16*P(1,22) - HK17*P(3,22) - HK21 - HK9*P(22,23) + HK9*P(5,22); const float HK23 = HK13*HK19; const float HK24 = HK12*P(4,6) - HK13*P(4,4) + HK14*P(2,4) + HK15*P(0,4) + HK16*P(1,4) - HK17*P(3,4) + HK21 - HK9*P(4,23) + HK9*P(4,5); const float HK25 = HK9*P(5,23); const float HK26 = HK12*P(5,6) - HK13*P(4,5) + HK13*P(5,22) + HK14*P(2,5) + HK15*P(0,5) + HK16*P(1,5) - HK17*P(3,5) - HK25 + HK9*P(5,5); const float HK27 = HK19*HK9; const float HK28 = HK12*P(6,23) + HK13*P(22,23) - HK13*P(4,23) + HK14*P(2,23) + HK15*P(0,23) + HK16*P(1,23) - HK17*P(3,23) + HK25 - HK9*P(23,23); const float HK29 = HK12*P(2,6) + HK13*P(2,22) - HK13*P(2,4) + HK14*P(2,2) + HK15*P(0,2) + HK16*P(1,2) - HK17*P(2,3) - HK9*P(2,23) + HK9*P(2,5); const float HK30 = HK12*P(1,6) + HK13*P(1,22) - HK13*P(1,4) + HK14*P(1,2) + HK15*P(0,1) + HK16*P(1,1) - HK17*P(1,3) - HK9*P(1,23) + HK9*P(1,5); const float HK31 = HK12*P(3,6) + HK13*P(3,22) - HK13*P(3,4) + HK14*P(2,3) + HK15*P(0,3) + HK16*P(1,3) - HK17*P(3,3) - HK9*P(3,23) + HK9*P(3,5); // const float HK32 = Kacc/(HK12*HK19*HK20 + HK14*HK19*HK29 + HK15*HK18*HK19 + HK16*HK19*HK30 - HK17*HK19*HK31 + HK22*HK23 - HK23*HK24 + HK26*HK27 - HK27*HK28 + R_ACC); _drag_innov_var(1) = (HK12*HK19*HK20 + HK14*HK19*HK29 + HK15*HK18*HK19 + HK16*HK19*HK30 - HK17*HK19*HK31 + HK22*HK23 - HK23*HK24 + HK26*HK27 - HK27*HK28 + R_ACC); if (_drag_innov_var(1) < R_ACC) { // calculation is badly conditioned return; } const float HK32 = Kacc / _drag_innov_var(1); // Observation Jacobians Hfusion.at<0>() = -HK2*HK3; Hfusion.at<1>() = -HK3*HK4; Hfusion.at<2>() = -HK3*HK5; Hfusion.at<3>() = HK3*HK6; Hfusion.at<4>() = HK8; Hfusion.at<5>() = -HK10; Hfusion.at<6>() = -HK11*HK3; Hfusion.at<22>() = -HK8; Hfusion.at<23>() = HK10; // Kalman gains // Don't allow modification of any states other than wind velocity at this stage of development - we only need a wind estimate. // Kfusion(0) = -HK18*HK32; // Kfusion(1) = -HK30*HK32; // Kfusion(2) = -HK29*HK32; // Kfusion(3) = -HK31*HK32; // Kfusion(4) = -HK24*HK32; // Kfusion(5) = -HK26*HK32; // Kfusion(6) = -HK20*HK32; // Kfusion(7) = -HK32*(HK12*P(6,7) - HK13*P(4,7) + HK13*P(7,22) + HK14*P(2,7) + HK15*P(0,7) + HK16*P(1,7) - HK17*P(3,7) + HK9*P(5,7) - HK9*P(7,23)); // Kfusion(8) = -HK32*(HK12*P(6,8) - HK13*P(4,8) + HK13*P(8,22) + HK14*P(2,8) + HK15*P(0,8) + HK16*P(1,8) - HK17*P(3,8) + HK9*P(5,8) - HK9*P(8,23)); // Kfusion(9) = -HK32*(HK12*P(6,9) - HK13*P(4,9) + HK13*P(9,22) + HK14*P(2,9) + HK15*P(0,9) + HK16*P(1,9) - HK17*P(3,9) + HK9*P(5,9) - HK9*P(9,23)); // Kfusion(10) = -HK32*(HK12*P(6,10) + HK13*P(10,22) - HK13*P(4,10) + HK14*P(2,10) + HK15*P(0,10) + HK16*P(1,10) - HK17*P(3,10) - HK9*P(10,23) + HK9*P(5,10)); // Kfusion(11) = -HK32*(HK12*P(6,11) + HK13*P(11,22) - HK13*P(4,11) + HK14*P(2,11) + HK15*P(0,11) + HK16*P(1,11) - HK17*P(3,11) - HK9*P(11,23) + HK9*P(5,11)); // Kfusion(12) = -HK32*(HK12*P(6,12) + HK13*P(12,22) - HK13*P(4,12) + HK14*P(2,12) + HK15*P(0,12) + HK16*P(1,12) - HK17*P(3,12) - HK9*P(12,23) + HK9*P(5,12)); // Kfusion(13) = -HK32*(HK12*P(6,13) + HK13*P(13,22) - HK13*P(4,13) + HK14*P(2,13) + HK15*P(0,13) + HK16*P(1,13) - HK17*P(3,13) - HK9*P(13,23) + HK9*P(5,13)); // Kfusion(14) = -HK32*(HK12*P(6,14) + HK13*P(14,22) - HK13*P(4,14) + HK14*P(2,14) + HK15*P(0,14) + HK16*P(1,14) - HK17*P(3,14) - HK9*P(14,23) + HK9*P(5,14)); // Kfusion(15) = -HK32*(HK12*P(6,15) + HK13*P(15,22) - HK13*P(4,15) + HK14*P(2,15) + HK15*P(0,15) + HK16*P(1,15) - HK17*P(3,15) - HK9*P(15,23) + HK9*P(5,15)); // Kfusion(16) = -HK32*(HK12*P(6,16) + HK13*P(16,22) - HK13*P(4,16) + HK14*P(2,16) + HK15*P(0,16) + HK16*P(1,16) - HK17*P(3,16) - HK9*P(16,23) + HK9*P(5,16)); // Kfusion(17) = -HK32*(HK12*P(6,17) + HK13*P(17,22) - HK13*P(4,17) + HK14*P(2,17) + HK15*P(0,17) + HK16*P(1,17) - HK17*P(3,17) - HK9*P(17,23) + HK9*P(5,17)); // Kfusion(18) = -HK32*(HK12*P(6,18) + HK13*P(18,22) - HK13*P(4,18) + HK14*P(2,18) + HK15*P(0,18) + HK16*P(1,18) - HK17*P(3,18) - HK9*P(18,23) + HK9*P(5,18)); // Kfusion(19) = -HK32*(HK12*P(6,19) + HK13*P(19,22) - HK13*P(4,19) + HK14*P(2,19) + HK15*P(0,19) + HK16*P(1,19) - HK17*P(3,19) - HK9*P(19,23) + HK9*P(5,19)); // Kfusion(20) = -HK32*(HK12*P(6,20) + HK13*P(20,22) - HK13*P(4,20) + HK14*P(2,20) + HK15*P(0,20) + HK16*P(1,20) - HK17*P(3,20) - HK9*P(20,23) + HK9*P(5,20)); // Kfusion(21) = -HK32*(HK12*P(6,21) + HK13*P(21,22) - HK13*P(4,21) + HK14*P(2,21) + HK15*P(0,21) + HK16*P(1,21) - HK17*P(3,21) - HK9*P(21,23) + HK9*P(5,21)); Kfusion(22) = -HK22*HK32; Kfusion(23) = -HK28*HK32; } // calculate the predicted acceleration and innovation measured along body axis const float drag_sign = (rel_wind_body(axis_index) >= 0.f) ? 1.f : -1.f; const float predAccel = -0.5f * ballistic_coef_inv_xy(axis_index) * rho * sq(rel_wind_body(axis_index)) * drag_sign; _drag_innov(axis_index) = predAccel - mea_acc; _drag_test_ratio(axis_index) = sq(_drag_innov(axis_index)) / (25.0f * _drag_innov_var(axis_index)); // if the innovation consistency check fails then don't fuse the sample if (_drag_test_ratio(axis_index) <= 1.0f) { measurementUpdate(Kfusion, Hfusion, _drag_innov(axis_index)); } } }