forked from Archive/PX4-Autopilot
314 lines
30 KiB
C++
314 lines
30 KiB
C++
/****************************************************************************
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*
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* Copyright (c) 2015 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 drag_fusion.cpp
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* body frame drag fusion methods used for multi-rotor wind estimation.
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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 "ekf.h"
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#include <ecl.h>
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#include <mathlib/mathlib.h>
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void Ekf::fuseDrag()
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{
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float SH_ACC[4] = {}; // Variable used to optimise calculations of measurement jacobian
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float H_ACC[24] = {}; // Observation Jacobian
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float SK_ACC[9] = {}; // Variable used to optimise calculations of the Kalman gain vector
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float Kfusion[24] = {}; // Kalman gain vector
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float R_ACC = _params.drag_noise; // observation noise variance in specific force drag (m/sec**2)**2
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float rho = fmaxf(_air_density, 0.1f); // air density (kg/m**3)
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// calculate inverse of ballistic coefficient
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if (_params.bcoef_x < 1.0f || _params.bcoef_y < 1.0f) {
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return;
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}
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float BC_inv_x = 1.0f / _params.bcoef_x;
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float BC_inv_y = 1.0f / _params.bcoef_y;
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// get latest estimated orientation
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float q0 = _state.quat_nominal(0);
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float q1 = _state.quat_nominal(1);
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float q2 = _state.quat_nominal(2);
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float q3 = _state.quat_nominal(3);
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// get latest velocity in earth frame
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float vn = _state.vel(0);
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float ve = _state.vel(1);
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float vd = _state.vel(2);
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// get latest wind velocity in earth frame
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float vwn = _state.wind_vel(0);
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float vwe = _state.wind_vel(1);
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// predicted specific forces
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// calculate relative wind velocity in earth frame and rotte into body frame
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Vector3f rel_wind;
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rel_wind(0) = vn - vwn;
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rel_wind(1) = ve - vwe;
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rel_wind(2) = vd;
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Dcmf earth_to_body = quat_to_invrotmat(_state.quat_nominal);
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rel_wind = earth_to_body * rel_wind;
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// perform sequential fusion of XY specific forces
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for (uint8_t axis_index = 0; axis_index < 2; axis_index++) {
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// calculate observation jacobiam and Kalman gain vectors
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if (axis_index == 0) {
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// Estimate the airspeed from the measured drag force and ballistic coefficient
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float mea_acc = _drag_sample_delayed.accelXY(axis_index) - _state.accel_bias(axis_index) / _dt_ekf_avg;
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float airSpd = sqrtf((2.0f * fabsf(mea_acc)) / (BC_inv_x * rho));
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// Estimate the derivative of specific force wrt airspeed along the X axis
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// Limit lower value to prevent arithmetic exceptions
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float Kacc = fmaxf(1e-1f, rho * BC_inv_x * airSpd);
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SH_ACC[0] = sq(q0) + sq(q1) - sq(q2) - sq(q3);
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SH_ACC[1] = vn - vwn;
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SH_ACC[2] = ve - vwe;
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SH_ACC[3] = 2.0f*q0*q3 + 2.0f*q1*q2;
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H_ACC[0] = -Kacc*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd);
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H_ACC[1] = -Kacc*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd);
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H_ACC[2] = Kacc*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd);
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H_ACC[3] = -Kacc*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd);
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H_ACC[4] = -Kacc*SH_ACC[0];
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H_ACC[5] = -Kacc*SH_ACC[3];
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H_ACC[6] = Kacc*(2.0f*q0*q2 - 2.0f*q1*q3);
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H_ACC[22] = Kacc*SH_ACC[0];
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H_ACC[23] = Kacc*SH_ACC[3];
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_drag_innov_var[0] = (R_ACC + Kacc*SH_ACC[0]*(Kacc*P[4][4]*SH_ACC[0] + Kacc*P[5][4]*SH_ACC[3] - Kacc*P[22][4]*SH_ACC[0] - Kacc*P[23][4]*SH_ACC[3] - Kacc*P[6][4]*(2.0f*q0*q2 - 2.0f*q1*q3) + Kacc*P[0][4]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd) + Kacc*P[1][4]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[2][4]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[3][4]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)) + Kacc*SH_ACC[3]*(Kacc*P[4][5]*SH_ACC[0] + Kacc*P[5][5]*SH_ACC[3] - Kacc*P[22][5]*SH_ACC[0] - Kacc*P[23][5]*SH_ACC[3] - Kacc*P[6][5]*(2.0f*q0*q2 - 2.0f*q1*q3) + Kacc*P[0][5]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd) + Kacc*P[1][5]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[2][5]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[3][5]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)) - Kacc*SH_ACC[0]*(Kacc*P[4][22]*SH_ACC[0] + Kacc*P[5][22]*SH_ACC[3] - Kacc*P[22][22]*SH_ACC[0] - Kacc*P[23][22]*SH_ACC[3] - Kacc*P[6][22]*(2.0f*q0*q2 - 2.0f*q1*q3) + Kacc*P[0][22]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd) + Kacc*P[1][22]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[2][22]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[3][22]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)) - Kacc*SH_ACC[3]*(Kacc*P[4][23]*SH_ACC[0] + Kacc*P[5][23]*SH_ACC[3] - Kacc*P[22][23]*SH_ACC[0] - Kacc*P[23][23]*SH_ACC[3] - Kacc*P[6][23]*(2.0f*q0*q2 - 2.0f*q1*q3) + Kacc*P[0][23]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd) + Kacc*P[1][23]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[2][23]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[3][23]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)) - Kacc*(2.0f*q0*q2 - 2.0f*q1*q3)*(Kacc*P[4][6]*SH_ACC[0] + Kacc*P[5][6]*SH_ACC[3] - Kacc*P[22][6]*SH_ACC[0] - Kacc*P[23][6]*SH_ACC[3] - Kacc*P[6][6]*(2.0f*q0*q2 - 2.0f*q1*q3) + Kacc*P[0][6]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd) + Kacc*P[1][6]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[2][6]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[3][6]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)) + Kacc*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)*(Kacc*P[4][0]*SH_ACC[0] + Kacc*P[5][0]*SH_ACC[3] - Kacc*P[22][0]*SH_ACC[0] - Kacc*P[23][0]*SH_ACC[3] - Kacc*P[6][0]*(2.0f*q0*q2 - 2.0f*q1*q3) + Kacc*P[0][0]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd) + Kacc*P[1][0]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[2][0]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[3][0]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)) + Kacc*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd)*(Kacc*P[4][1]*SH_ACC[0] + Kacc*P[5][1]*SH_ACC[3] - Kacc*P[22][1]*SH_ACC[0] - Kacc*P[23][1]*SH_ACC[3] - Kacc*P[6][1]*(2.0f*q0*q2 - 2.0f*q1*q3) + Kacc*P[0][1]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd) + Kacc*P[1][1]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[2][1]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[3][1]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)) - Kacc*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd)*(Kacc*P[4][2]*SH_ACC[0] + Kacc*P[5][2]*SH_ACC[3] - Kacc*P[22][2]*SH_ACC[0] - Kacc*P[23][2]*SH_ACC[3] - Kacc*P[6][2]*(2.0f*q0*q2 - 2.0f*q1*q3) + Kacc*P[0][2]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd) + Kacc*P[1][2]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[2][2]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[3][2]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)) + Kacc*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)*(Kacc*P[4][3]*SH_ACC[0] + Kacc*P[5][3]*SH_ACC[3] - Kacc*P[22][3]*SH_ACC[0] - Kacc*P[23][3]*SH_ACC[3] - Kacc*P[6][3]*(2.0f*q0*q2 - 2.0f*q1*q3) + Kacc*P[0][3]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd) + Kacc*P[1][3]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[2][3]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[3][3]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)));
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if (_drag_innov_var[0] < R_ACC) {
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return;
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}
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SK_ACC[0] = 1.0f/_drag_innov_var[0];
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SK_ACC[1] = 2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd;
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SK_ACC[2] = 2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd;
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SK_ACC[3] = 2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd;
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SK_ACC[4] = 2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd;
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SK_ACC[5] = 2.0f*q0*q2 - 2.0f*q1*q3;
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SK_ACC[6] = SH_ACC[3];
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// Don't allow modification of any states other than wind velocity at this stage of development - we only need a wind estimate.
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// Kfusion[0] = -SK_ACC[0]*(Kacc*P[0][4]*SH_ACC[0] - Kacc*P[0][22]*SH_ACC[0] + Kacc*P[0][0]*SK_ACC[3] - Kacc*P[0][2]*SK_ACC[2] + Kacc*P[0][3]*SK_ACC[1] + Kacc*P[0][1]*SK_ACC[4] + Kacc*P[0][5]*SK_ACC[6] - Kacc*P[0][6]*SK_ACC[5] - Kacc*P[0][23]*SK_ACC[6]);
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// Kfusion[1] = -SK_ACC[0]*(Kacc*P[1][4]*SH_ACC[0] - Kacc*P[1][22]*SH_ACC[0] + Kacc*P[1][0]*SK_ACC[3] - Kacc*P[1][2]*SK_ACC[2] + Kacc*P[1][3]*SK_ACC[1] + Kacc*P[1][1]*SK_ACC[4] + Kacc*P[1][5]*SK_ACC[6] - Kacc*P[1][6]*SK_ACC[5] - Kacc*P[1][23]*SK_ACC[6]);
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// Kfusion[2] = -SK_ACC[0]*(Kacc*P[2][4]*SH_ACC[0] - Kacc*P[2][22]*SH_ACC[0] + Kacc*P[2][0]*SK_ACC[3] - Kacc*P[2][2]*SK_ACC[2] + Kacc*P[2][3]*SK_ACC[1] + Kacc*P[2][1]*SK_ACC[4] + Kacc*P[2][5]*SK_ACC[6] - Kacc*P[2][6]*SK_ACC[5] - Kacc*P[2][23]*SK_ACC[6]);
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// Kfusion[3] = -SK_ACC[0]*(Kacc*P[3][4]*SH_ACC[0] - Kacc*P[3][22]*SH_ACC[0] + Kacc*P[3][0]*SK_ACC[3] - Kacc*P[3][2]*SK_ACC[2] + Kacc*P[3][3]*SK_ACC[1] + Kacc*P[3][1]*SK_ACC[4] + Kacc*P[3][5]*SK_ACC[6] - Kacc*P[3][6]*SK_ACC[5] - Kacc*P[3][23]*SK_ACC[6]);
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// Kfusion[4] = -SK_ACC[0]*(Kacc*P[4][4]*SH_ACC[0] - Kacc*P[4][22]*SH_ACC[0] + Kacc*P[4][0]*SK_ACC[3] - Kacc*P[4][2]*SK_ACC[2] + Kacc*P[4][3]*SK_ACC[1] + Kacc*P[4][1]*SK_ACC[4] + Kacc*P[4][5]*SK_ACC[6] - Kacc*P[4][6]*SK_ACC[5] - Kacc*P[4][23]*SK_ACC[6]);
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// Kfusion[5] = -SK_ACC[0]*(Kacc*P[5][4]*SH_ACC[0] - Kacc*P[5][22]*SH_ACC[0] + Kacc*P[5][0]*SK_ACC[3] - Kacc*P[5][2]*SK_ACC[2] + Kacc*P[5][3]*SK_ACC[1] + Kacc*P[5][1]*SK_ACC[4] + Kacc*P[5][5]*SK_ACC[6] - Kacc*P[5][6]*SK_ACC[5] - Kacc*P[5][23]*SK_ACC[6]);
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// Kfusion[6] = -SK_ACC[0]*(Kacc*P[6][4]*SH_ACC[0] - Kacc*P[6][22]*SH_ACC[0] + Kacc*P[6][0]*SK_ACC[3] - Kacc*P[6][2]*SK_ACC[2] + Kacc*P[6][3]*SK_ACC[1] + Kacc*P[6][1]*SK_ACC[4] + Kacc*P[6][5]*SK_ACC[6] - Kacc*P[6][6]*SK_ACC[5] - Kacc*P[6][23]*SK_ACC[6]);
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// Kfusion[7] = -SK_ACC[0]*(Kacc*P[7][4]*SH_ACC[0] - Kacc*P[7][22]*SH_ACC[0] + Kacc*P[7][0]*SK_ACC[3] - Kacc*P[7][2]*SK_ACC[2] + Kacc*P[7][3]*SK_ACC[1] + Kacc*P[7][1]*SK_ACC[4] + Kacc*P[7][5]*SK_ACC[6] - Kacc*P[7][6]*SK_ACC[5] - Kacc*P[7][23]*SK_ACC[6]);
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// Kfusion[8] = -SK_ACC[0]*(Kacc*P[8][4]*SH_ACC[0] - Kacc*P[8][22]*SH_ACC[0] + Kacc*P[8][0]*SK_ACC[3] - Kacc*P[8][2]*SK_ACC[2] + Kacc*P[8][3]*SK_ACC[1] + Kacc*P[8][1]*SK_ACC[4] + Kacc*P[8][5]*SK_ACC[6] - Kacc*P[8][6]*SK_ACC[5] - Kacc*P[8][23]*SK_ACC[6]);
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// Kfusion[9] = -SK_ACC[0]*(Kacc*P[9][4]*SH_ACC[0] - Kacc*P[9][22]*SH_ACC[0] + Kacc*P[9][0]*SK_ACC[3] - Kacc*P[9][2]*SK_ACC[2] + Kacc*P[9][3]*SK_ACC[1] + Kacc*P[9][1]*SK_ACC[4] + Kacc*P[9][5]*SK_ACC[6] - Kacc*P[9][6]*SK_ACC[5] - Kacc*P[9][23]*SK_ACC[6]);
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// Kfusion[10] = -SK_ACC[0]*(Kacc*P[10][4]*SH_ACC[0] - Kacc*P[10][22]*SH_ACC[0] + Kacc*P[10][0]*SK_ACC[3] - Kacc*P[10][2]*SK_ACC[2] + Kacc*P[10][3]*SK_ACC[1] + Kacc*P[10][1]*SK_ACC[4] + Kacc*P[10][5]*SK_ACC[6] - Kacc*P[10][6]*SK_ACC[5] - Kacc*P[10][23]*SK_ACC[6]);
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// Kfusion[11] = -SK_ACC[0]*(Kacc*P[11][4]*SH_ACC[0] - Kacc*P[11][22]*SH_ACC[0] + Kacc*P[11][0]*SK_ACC[3] - Kacc*P[11][2]*SK_ACC[2] + Kacc*P[11][3]*SK_ACC[1] + Kacc*P[11][1]*SK_ACC[4] + Kacc*P[11][5]*SK_ACC[6] - Kacc*P[11][6]*SK_ACC[5] - Kacc*P[11][23]*SK_ACC[6]);
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// Kfusion[12] = -SK_ACC[0]*(Kacc*P[12][4]*SH_ACC[0] - Kacc*P[12][22]*SH_ACC[0] + Kacc*P[12][0]*SK_ACC[3] - Kacc*P[12][2]*SK_ACC[2] + Kacc*P[12][3]*SK_ACC[1] + Kacc*P[12][1]*SK_ACC[4] + Kacc*P[12][5]*SK_ACC[6] - Kacc*P[12][6]*SK_ACC[5] - Kacc*P[12][23]*SK_ACC[6]);
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// Kfusion[13] = -SK_ACC[0]*(Kacc*P[13][4]*SH_ACC[0] - Kacc*P[13][22]*SH_ACC[0] + Kacc*P[13][0]*SK_ACC[3] - Kacc*P[13][2]*SK_ACC[2] + Kacc*P[13][3]*SK_ACC[1] + Kacc*P[13][1]*SK_ACC[4] + Kacc*P[13][5]*SK_ACC[6] - Kacc*P[13][6]*SK_ACC[5] - Kacc*P[13][23]*SK_ACC[6]);
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// Kfusion[14] = -SK_ACC[0]*(Kacc*P[14][4]*SH_ACC[0] - Kacc*P[14][22]*SH_ACC[0] + Kacc*P[14][0]*SK_ACC[3] - Kacc*P[14][2]*SK_ACC[2] + Kacc*P[14][3]*SK_ACC[1] + Kacc*P[14][1]*SK_ACC[4] + Kacc*P[14][5]*SK_ACC[6] - Kacc*P[14][6]*SK_ACC[5] - Kacc*P[14][23]*SK_ACC[6]);
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// Kfusion[15] = -SK_ACC[0]*(Kacc*P[15][4]*SH_ACC[0] - Kacc*P[15][22]*SH_ACC[0] + Kacc*P[15][0]*SK_ACC[3] - Kacc*P[15][2]*SK_ACC[2] + Kacc*P[15][3]*SK_ACC[1] + Kacc*P[15][1]*SK_ACC[4] + Kacc*P[15][5]*SK_ACC[6] - Kacc*P[15][6]*SK_ACC[5] - Kacc*P[15][23]*SK_ACC[6]);
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// Kfusion[16] = -SK_ACC[0]*(Kacc*P[16][4]*SH_ACC[0] - Kacc*P[16][22]*SH_ACC[0] + Kacc*P[16][0]*SK_ACC[3] - Kacc*P[16][2]*SK_ACC[2] + Kacc*P[16][3]*SK_ACC[1] + Kacc*P[16][1]*SK_ACC[4] + Kacc*P[16][5]*SK_ACC[6] - Kacc*P[16][6]*SK_ACC[5] - Kacc*P[16][23]*SK_ACC[6]);
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// Kfusion[17] = -SK_ACC[0]*(Kacc*P[17][4]*SH_ACC[0] - Kacc*P[17][22]*SH_ACC[0] + Kacc*P[17][0]*SK_ACC[3] - Kacc*P[17][2]*SK_ACC[2] + Kacc*P[17][3]*SK_ACC[1] + Kacc*P[17][1]*SK_ACC[4] + Kacc*P[17][5]*SK_ACC[6] - Kacc*P[17][6]*SK_ACC[5] - Kacc*P[17][23]*SK_ACC[6]);
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// Kfusion[18] = -SK_ACC[0]*(Kacc*P[18][4]*SH_ACC[0] - Kacc*P[18][22]*SH_ACC[0] + Kacc*P[18][0]*SK_ACC[3] - Kacc*P[18][2]*SK_ACC[2] + Kacc*P[18][3]*SK_ACC[1] + Kacc*P[18][1]*SK_ACC[4] + Kacc*P[18][5]*SK_ACC[6] - Kacc*P[18][6]*SK_ACC[5] - Kacc*P[18][23]*SK_ACC[6]);
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// Kfusion[19] = -SK_ACC[0]*(Kacc*P[19][4]*SH_ACC[0] - Kacc*P[19][22]*SH_ACC[0] + Kacc*P[19][0]*SK_ACC[3] - Kacc*P[19][2]*SK_ACC[2] + Kacc*P[19][3]*SK_ACC[1] + Kacc*P[19][1]*SK_ACC[4] + Kacc*P[19][5]*SK_ACC[6] - Kacc*P[19][6]*SK_ACC[5] - Kacc*P[19][23]*SK_ACC[6]);
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// Kfusion[20] = -SK_ACC[0]*(Kacc*P[20][4]*SH_ACC[0] - Kacc*P[20][22]*SH_ACC[0] + Kacc*P[20][0]*SK_ACC[3] - Kacc*P[20][2]*SK_ACC[2] + Kacc*P[20][3]*SK_ACC[1] + Kacc*P[20][1]*SK_ACC[4] + Kacc*P[20][5]*SK_ACC[6] - Kacc*P[20][6]*SK_ACC[5] - Kacc*P[20][23]*SK_ACC[6]);
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// Kfusion[21] = -SK_ACC[0]*(Kacc*P[21][4]*SH_ACC[0] - Kacc*P[21][22]*SH_ACC[0] + Kacc*P[21][0]*SK_ACC[3] - Kacc*P[21][2]*SK_ACC[2] + Kacc*P[21][3]*SK_ACC[1] + Kacc*P[21][1]*SK_ACC[4] + Kacc*P[21][5]*SK_ACC[6] - Kacc*P[21][6]*SK_ACC[5] - Kacc*P[21][23]*SK_ACC[6]);
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Kfusion[22] = -SK_ACC[0]*(Kacc*P[22][4]*SH_ACC[0] - Kacc*P[22][22]*SH_ACC[0] + Kacc*P[22][0]*SK_ACC[3] - Kacc*P[22][2]*SK_ACC[2] + Kacc*P[22][3]*SK_ACC[1] + Kacc*P[22][1]*SK_ACC[4] + Kacc*P[22][5]*SK_ACC[6] - Kacc*P[22][6]*SK_ACC[5] - Kacc*P[22][23]*SK_ACC[6]);
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Kfusion[23] = -SK_ACC[0]*(Kacc*P[23][4]*SH_ACC[0] - Kacc*P[23][22]*SH_ACC[0] + Kacc*P[23][0]*SK_ACC[3] - Kacc*P[23][2]*SK_ACC[2] + Kacc*P[23][3]*SK_ACC[1] + Kacc*P[23][1]*SK_ACC[4] + Kacc*P[23][5]*SK_ACC[6] - Kacc*P[23][6]*SK_ACC[5] - Kacc*P[23][23]*SK_ACC[6]);
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// calculate the predicted acceleration and innovation measured along the X body axis
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float drag_sign;
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if (rel_wind(axis_index) >= 0.0f) {
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drag_sign = 1.0f;
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} else {
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drag_sign = -1.0f;
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}
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float predAccel = -BC_inv_x * 0.5f * rho * sq(rel_wind(axis_index)) * drag_sign;
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_drag_innov[axis_index] = predAccel - mea_acc;
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_drag_test_ratio[axis_index] = sq(_drag_innov[axis_index]) / (25.0f * _drag_innov_var[axis_index]);
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} else if (axis_index == 1) {
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// Estimate the airspeed from the measured drag force and ballistic coefficient
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float mea_acc = _drag_sample_delayed.accelXY(axis_index) - _state.accel_bias(axis_index) / _dt_ekf_avg;
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float airSpd = sqrtf((2.0f * fabsf(mea_acc)) / (BC_inv_y * rho));
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// Estimate the derivative of specific force wrt airspeed along the X axis
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// Limit lower value to prevent arithmetic exceptions
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float Kacc = fmaxf(1e-1f, rho * BC_inv_y * airSpd);
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SH_ACC[0] = sq(q0) - sq(q1) + sq(q2) - sq(q3);
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SH_ACC[1] = vn - vwn;
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SH_ACC[2] = ve - vwe;
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H_ACC[0] = -Kacc*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd);
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H_ACC[1] = -Kacc*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd);
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H_ACC[2] = -Kacc*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd);
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H_ACC[3] = Kacc*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd);
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H_ACC[4] = Kacc*(2.0f*q0*q3 - 2.0f*q1*q2);
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H_ACC[5] = -Kacc*SH_ACC[0];
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H_ACC[6] = -Kacc*(2.0f*q0*q1 + 2.0f*q2*q3);
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H_ACC[22] = -2.0f*Kacc*(q0*q3 - q1*q2);
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H_ACC[23] = Kacc*SH_ACC[0];
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_drag_innov_var[1] = (R_ACC + Kacc*SH_ACC[0]*(Kacc*P[5][5]*SH_ACC[0] - Kacc*P[23][5]*SH_ACC[0] - Kacc*P[4][5]*(2.0f*q0*q3 - 2.0f*q1*q2) + Kacc*P[6][5]*(2.0f*q0*q1 + 2.0f*q2*q3) + 2*Kacc*P[22][5]*(q0*q3 - q1*q2) + Kacc*P[0][5]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd) + Kacc*P[1][5]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[2][5]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[3][5]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)) - Kacc*SH_ACC[0]*(Kacc*P[5][23]*SH_ACC[0] - Kacc*P[23][23]*SH_ACC[0] - Kacc*P[4][23]*(2.0f*q0*q3 - 2.0f*q1*q2) + Kacc*P[6][23]*(2.0f*q0*q1 + 2.0f*q2*q3) + 2*Kacc*P[22][23]*(q0*q3 - q1*q2) + Kacc*P[0][23]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd) + Kacc*P[1][23]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[2][23]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[3][23]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)) - Kacc*(2.0f*q0*q3 - 2.0f*q1*q2)*(Kacc*P[5][4]*SH_ACC[0] - Kacc*P[23][4]*SH_ACC[0] - Kacc*P[4][4]*(2.0f*q0*q3 - 2.0f*q1*q2) + Kacc*P[6][4]*(2.0f*q0*q1 + 2.0f*q2*q3) + 2*Kacc*P[22][4]*(q0*q3 - q1*q2) + Kacc*P[0][4]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd) + Kacc*P[1][4]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[2][4]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[3][4]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)) + Kacc*(2.0f*q0*q1 + 2.0f*q2*q3)*(Kacc*P[5][6]*SH_ACC[0] - Kacc*P[23][6]*SH_ACC[0] - Kacc*P[4][6]*(2.0f*q0*q3 - 2.0f*q1*q2) + Kacc*P[6][6]*(2.0f*q0*q1 + 2.0f*q2*q3) + 2*Kacc*P[22][6]*(q0*q3 - q1*q2) + Kacc*P[0][6]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd) + Kacc*P[1][6]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[2][6]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[3][6]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)) + 2*Kacc*(q0*q3 - q1*q2)*(Kacc*P[5][22]*SH_ACC[0] - Kacc*P[23][22]*SH_ACC[0] - Kacc*P[4][22]*(2.0f*q0*q3 - 2.0f*q1*q2) + Kacc*P[6][22]*(2.0f*q0*q1 + 2.0f*q2*q3) + 2*Kacc*P[22][22]*(q0*q3 - q1*q2) + Kacc*P[0][22]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd) + Kacc*P[1][22]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[2][22]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[3][22]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)) + Kacc*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd)*(Kacc*P[5][0]*SH_ACC[0] - Kacc*P[23][0]*SH_ACC[0] - Kacc*P[4][0]*(2.0f*q0*q3 - 2.0f*q1*q2) + Kacc*P[6][0]*(2.0f*q0*q1 + 2.0f*q2*q3) + 2*Kacc*P[22][0]*(q0*q3 - q1*q2) + Kacc*P[0][0]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd) + Kacc*P[1][0]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[2][0]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[3][0]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)) + Kacc*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd)*(Kacc*P[5][1]*SH_ACC[0] - Kacc*P[23][1]*SH_ACC[0] - Kacc*P[4][1]*(2.0f*q0*q3 - 2.0f*q1*q2) + Kacc*P[6][1]*(2.0f*q0*q1 + 2.0f*q2*q3) + 2*Kacc*P[22][1]*(q0*q3 - q1*q2) + Kacc*P[0][1]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd) + Kacc*P[1][1]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[2][1]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[3][1]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)) + Kacc*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd)*(Kacc*P[5][2]*SH_ACC[0] - Kacc*P[23][2]*SH_ACC[0] - Kacc*P[4][2]*(2.0f*q0*q3 - 2.0f*q1*q2) + Kacc*P[6][2]*(2.0f*q0*q1 + 2.0f*q2*q3) + 2*Kacc*P[22][2]*(q0*q3 - q1*q2) + Kacc*P[0][2]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd) + Kacc*P[1][2]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[2][2]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[3][2]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)) - Kacc*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)*(Kacc*P[5][3]*SH_ACC[0] - Kacc*P[23][3]*SH_ACC[0] - Kacc*P[4][3]*(2.0f*q0*q3 - 2.0f*q1*q2) + Kacc*P[6][3]*(2.0f*q0*q1 + 2.0f*q2*q3) + 2*Kacc*P[22][3]*(q0*q3 - q1*q2) + Kacc*P[0][3]*(2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd) + Kacc*P[1][3]*(2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd) + Kacc*P[2][3]*(2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd) - Kacc*P[3][3]*(2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd)));
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if (_drag_innov_var[1] < R_ACC) {
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// calculation is badly conditioned
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return;
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}
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SK_ACC[0] = 1.0f/_drag_innov_var[1];
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|
SK_ACC[1] = 2.0f*q0*SH_ACC[1] + 2.0f*q3*SH_ACC[2] - 2.0f*q2*vd;
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SK_ACC[2] = 2.0f*q2*SH_ACC[1] - 2.0f*q1*SH_ACC[2] + 2.0f*q0*vd;
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SK_ACC[3] = 2.0f*q0*SH_ACC[2] - 2.0f*q3*SH_ACC[1] + 2.0f*q1*vd;
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SK_ACC[4] = 2.0f*q1*SH_ACC[1] + 2.0f*q2*SH_ACC[2] + 2.0f*q3*vd;
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|
SK_ACC[5] = 2.0f*q0*q3 - 2.0f*q1*q2;
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SK_ACC[6] = q0*q3 - q1*q2;
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SK_ACC[7] = 2.0f*q0*q1 + 2.0f*q2*q3;
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|
SK_ACC[8] = SH_ACC[0];
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|
// Don't allow modification of any states other than wind velocity at this stage of development - we only need a wind estimate.
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|
// Kfusion[0] = -SK_ACC[0]*(Kacc*P[0][0]*SK_ACC[3] + Kacc*P[0][1]*SK_ACC[2] - Kacc*P[0][3]*SK_ACC[1] + Kacc*P[0][2]*SK_ACC[4] - Kacc*P[0][4]*SK_ACC[5] + Kacc*P[0][5]*SK_ACC[8] + Kacc*P[0][6]*SK_ACC[7] + 2*Kacc*P[0][22]*SK_ACC[6] - Kacc*P[0][23]*SK_ACC[8]);
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// Kfusion[1] = -SK_ACC[0]*(Kacc*P[1][0]*SK_ACC[3] + Kacc*P[1][1]*SK_ACC[2] - Kacc*P[1][3]*SK_ACC[1] + Kacc*P[1][2]*SK_ACC[4] - Kacc*P[1][4]*SK_ACC[5] + Kacc*P[1][5]*SK_ACC[8] + Kacc*P[1][6]*SK_ACC[7] + 2*Kacc*P[1][22]*SK_ACC[6] - Kacc*P[1][23]*SK_ACC[8]);
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// Kfusion[2] = -SK_ACC[0]*(Kacc*P[2][0]*SK_ACC[3] + Kacc*P[2][1]*SK_ACC[2] - Kacc*P[2][3]*SK_ACC[1] + Kacc*P[2][2]*SK_ACC[4] - Kacc*P[2][4]*SK_ACC[5] + Kacc*P[2][5]*SK_ACC[8] + Kacc*P[2][6]*SK_ACC[7] + 2*Kacc*P[2][22]*SK_ACC[6] - Kacc*P[2][23]*SK_ACC[8]);
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// Kfusion[3] = -SK_ACC[0]*(Kacc*P[3][0]*SK_ACC[3] + Kacc*P[3][1]*SK_ACC[2] - Kacc*P[3][3]*SK_ACC[1] + Kacc*P[3][2]*SK_ACC[4] - Kacc*P[3][4]*SK_ACC[5] + Kacc*P[3][5]*SK_ACC[8] + Kacc*P[3][6]*SK_ACC[7] + 2*Kacc*P[3][22]*SK_ACC[6] - Kacc*P[3][23]*SK_ACC[8]);
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// Kfusion[4] = -SK_ACC[0]*(Kacc*P[4][0]*SK_ACC[3] + Kacc*P[4][1]*SK_ACC[2] - Kacc*P[4][3]*SK_ACC[1] + Kacc*P[4][2]*SK_ACC[4] - Kacc*P[4][4]*SK_ACC[5] + Kacc*P[4][5]*SK_ACC[8] + Kacc*P[4][6]*SK_ACC[7] + 2*Kacc*P[4][22]*SK_ACC[6] - Kacc*P[4][23]*SK_ACC[8]);
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// Kfusion[5] = -SK_ACC[0]*(Kacc*P[5][0]*SK_ACC[3] + Kacc*P[5][1]*SK_ACC[2] - Kacc*P[5][3]*SK_ACC[1] + Kacc*P[5][2]*SK_ACC[4] - Kacc*P[5][4]*SK_ACC[5] + Kacc*P[5][5]*SK_ACC[8] + Kacc*P[5][6]*SK_ACC[7] + 2*Kacc*P[5][22]*SK_ACC[6] - Kacc*P[5][23]*SK_ACC[8]);
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// Kfusion[6] = -SK_ACC[0]*(Kacc*P[6][0]*SK_ACC[3] + Kacc*P[6][1]*SK_ACC[2] - Kacc*P[6][3]*SK_ACC[1] + Kacc*P[6][2]*SK_ACC[4] - Kacc*P[6][4]*SK_ACC[5] + Kacc*P[6][5]*SK_ACC[8] + Kacc*P[6][6]*SK_ACC[7] + 2*Kacc*P[6][22]*SK_ACC[6] - Kacc*P[6][23]*SK_ACC[8]);
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// Kfusion[7] = -SK_ACC[0]*(Kacc*P[7][0]*SK_ACC[3] + Kacc*P[7][1]*SK_ACC[2] - Kacc*P[7][3]*SK_ACC[1] + Kacc*P[7][2]*SK_ACC[4] - Kacc*P[7][4]*SK_ACC[5] + Kacc*P[7][5]*SK_ACC[8] + Kacc*P[7][6]*SK_ACC[7] + 2*Kacc*P[7][22]*SK_ACC[6] - Kacc*P[7][23]*SK_ACC[8]);
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// Kfusion[8] = -SK_ACC[0]*(Kacc*P[8][0]*SK_ACC[3] + Kacc*P[8][1]*SK_ACC[2] - Kacc*P[8][3]*SK_ACC[1] + Kacc*P[8][2]*SK_ACC[4] - Kacc*P[8][4]*SK_ACC[5] + Kacc*P[8][5]*SK_ACC[8] + Kacc*P[8][6]*SK_ACC[7] + 2*Kacc*P[8][22]*SK_ACC[6] - Kacc*P[8][23]*SK_ACC[8]);
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// Kfusion[9] = -SK_ACC[0]*(Kacc*P[9][0]*SK_ACC[3] + Kacc*P[9][1]*SK_ACC[2] - Kacc*P[9][3]*SK_ACC[1] + Kacc*P[9][2]*SK_ACC[4] - Kacc*P[9][4]*SK_ACC[5] + Kacc*P[9][5]*SK_ACC[8] + Kacc*P[9][6]*SK_ACC[7] + 2*Kacc*P[9][22]*SK_ACC[6] - Kacc*P[9][23]*SK_ACC[8]);
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// Kfusion[10] = -SK_ACC[0]*(Kacc*P[10][0]*SK_ACC[3] + Kacc*P[10][1]*SK_ACC[2] - Kacc*P[10][3]*SK_ACC[1] + Kacc*P[10][2]*SK_ACC[4] - Kacc*P[10][4]*SK_ACC[5] + Kacc*P[10][5]*SK_ACC[8] + Kacc*P[10][6]*SK_ACC[7] + 2*Kacc*P[10][22]*SK_ACC[6] - Kacc*P[10][23]*SK_ACC[8]);
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// Kfusion[11] = -SK_ACC[0]*(Kacc*P[11][0]*SK_ACC[3] + Kacc*P[11][1]*SK_ACC[2] - Kacc*P[11][3]*SK_ACC[1] + Kacc*P[11][2]*SK_ACC[4] - Kacc*P[11][4]*SK_ACC[5] + Kacc*P[11][5]*SK_ACC[8] + Kacc*P[11][6]*SK_ACC[7] + 2*Kacc*P[11][22]*SK_ACC[6] - Kacc*P[11][23]*SK_ACC[8]);
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// Kfusion[12] = -SK_ACC[0]*(Kacc*P[12][0]*SK_ACC[3] + Kacc*P[12][1]*SK_ACC[2] - Kacc*P[12][3]*SK_ACC[1] + Kacc*P[12][2]*SK_ACC[4] - Kacc*P[12][4]*SK_ACC[5] + Kacc*P[12][5]*SK_ACC[8] + Kacc*P[12][6]*SK_ACC[7] + 2*Kacc*P[12][22]*SK_ACC[6] - Kacc*P[12][23]*SK_ACC[8]);
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// Kfusion[13] = -SK_ACC[0]*(Kacc*P[13][0]*SK_ACC[3] + Kacc*P[13][1]*SK_ACC[2] - Kacc*P[13][3]*SK_ACC[1] + Kacc*P[13][2]*SK_ACC[4] - Kacc*P[13][4]*SK_ACC[5] + Kacc*P[13][5]*SK_ACC[8] + Kacc*P[13][6]*SK_ACC[7] + 2*Kacc*P[13][22]*SK_ACC[6] - Kacc*P[13][23]*SK_ACC[8]);
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// Kfusion[14] = -SK_ACC[0]*(Kacc*P[14][0]*SK_ACC[3] + Kacc*P[14][1]*SK_ACC[2] - Kacc*P[14][3]*SK_ACC[1] + Kacc*P[14][2]*SK_ACC[4] - Kacc*P[14][4]*SK_ACC[5] + Kacc*P[14][5]*SK_ACC[8] + Kacc*P[14][6]*SK_ACC[7] + 2*Kacc*P[14][22]*SK_ACC[6] - Kacc*P[14][23]*SK_ACC[8]);
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// Kfusion[15] = -SK_ACC[0]*(Kacc*P[15][0]*SK_ACC[3] + Kacc*P[15][1]*SK_ACC[2] - Kacc*P[15][3]*SK_ACC[1] + Kacc*P[15][2]*SK_ACC[4] - Kacc*P[15][4]*SK_ACC[5] + Kacc*P[15][5]*SK_ACC[8] + Kacc*P[15][6]*SK_ACC[7] + 2*Kacc*P[15][22]*SK_ACC[6] - Kacc*P[15][23]*SK_ACC[8]);
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// Kfusion[16] = -SK_ACC[0]*(Kacc*P[16][0]*SK_ACC[3] + Kacc*P[16][1]*SK_ACC[2] - Kacc*P[16][3]*SK_ACC[1] + Kacc*P[16][2]*SK_ACC[4] - Kacc*P[16][4]*SK_ACC[5] + Kacc*P[16][5]*SK_ACC[8] + Kacc*P[16][6]*SK_ACC[7] + 2*Kacc*P[16][22]*SK_ACC[6] - Kacc*P[16][23]*SK_ACC[8]);
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// Kfusion[17] = -SK_ACC[0]*(Kacc*P[17][0]*SK_ACC[3] + Kacc*P[17][1]*SK_ACC[2] - Kacc*P[17][3]*SK_ACC[1] + Kacc*P[17][2]*SK_ACC[4] - Kacc*P[17][4]*SK_ACC[5] + Kacc*P[17][5]*SK_ACC[8] + Kacc*P[17][6]*SK_ACC[7] + 2*Kacc*P[17][22]*SK_ACC[6] - Kacc*P[17][23]*SK_ACC[8]);
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// Kfusion[18] = -SK_ACC[0]*(Kacc*P[18][0]*SK_ACC[3] + Kacc*P[18][1]*SK_ACC[2] - Kacc*P[18][3]*SK_ACC[1] + Kacc*P[18][2]*SK_ACC[4] - Kacc*P[18][4]*SK_ACC[5] + Kacc*P[18][5]*SK_ACC[8] + Kacc*P[18][6]*SK_ACC[7] + 2*Kacc*P[18][22]*SK_ACC[6] - Kacc*P[18][23]*SK_ACC[8]);
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// Kfusion[19] = -SK_ACC[0]*(Kacc*P[19][0]*SK_ACC[3] + Kacc*P[19][1]*SK_ACC[2] - Kacc*P[19][3]*SK_ACC[1] + Kacc*P[19][2]*SK_ACC[4] - Kacc*P[19][4]*SK_ACC[5] + Kacc*P[19][5]*SK_ACC[8] + Kacc*P[19][6]*SK_ACC[7] + 2*Kacc*P[19][22]*SK_ACC[6] - Kacc*P[19][23]*SK_ACC[8]);
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// Kfusion[20] = -SK_ACC[0]*(Kacc*P[20][0]*SK_ACC[3] + Kacc*P[20][1]*SK_ACC[2] - Kacc*P[20][3]*SK_ACC[1] + Kacc*P[20][2]*SK_ACC[4] - Kacc*P[20][4]*SK_ACC[5] + Kacc*P[20][5]*SK_ACC[8] + Kacc*P[20][6]*SK_ACC[7] + 2*Kacc*P[20][22]*SK_ACC[6] - Kacc*P[20][23]*SK_ACC[8]);
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// Kfusion[21] = -SK_ACC[0]*(Kacc*P[21][0]*SK_ACC[3] + Kacc*P[21][1]*SK_ACC[2] - Kacc*P[21][3]*SK_ACC[1] + Kacc*P[21][2]*SK_ACC[4] - Kacc*P[21][4]*SK_ACC[5] + Kacc*P[21][5]*SK_ACC[8] + Kacc*P[21][6]*SK_ACC[7] + 2*Kacc*P[21][22]*SK_ACC[6] - Kacc*P[21][23]*SK_ACC[8]);
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Kfusion[22] = -SK_ACC[0]*(Kacc*P[22][0]*SK_ACC[3] + Kacc*P[22][1]*SK_ACC[2] - Kacc*P[22][3]*SK_ACC[1] + Kacc*P[22][2]*SK_ACC[4] - Kacc*P[22][4]*SK_ACC[5] + Kacc*P[22][5]*SK_ACC[8] + Kacc*P[22][6]*SK_ACC[7] + 2*Kacc*P[22][22]*SK_ACC[6] - Kacc*P[22][23]*SK_ACC[8]);
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Kfusion[23] = -SK_ACC[0]*(Kacc*P[23][0]*SK_ACC[3] + Kacc*P[23][1]*SK_ACC[2] - Kacc*P[23][3]*SK_ACC[1] + Kacc*P[23][2]*SK_ACC[4] - Kacc*P[23][4]*SK_ACC[5] + Kacc*P[23][5]*SK_ACC[8] + Kacc*P[23][6]*SK_ACC[7] + 2*Kacc*P[23][22]*SK_ACC[6] - Kacc*P[23][23]*SK_ACC[8]);
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// calculate the predicted acceleration and innovation measured along the Y body axis
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float drag_sign;
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if (rel_wind(axis_index) >= 0.0f) {
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drag_sign = 1.0f;
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} else {
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drag_sign = -1.0f;
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}
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float predAccel = -BC_inv_y * 0.5f * rho * sq(rel_wind(axis_index)) * drag_sign;
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_drag_innov[axis_index] = predAccel - mea_acc;
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_drag_test_ratio[axis_index] = sq(_drag_innov[axis_index]) / (25.0f * _drag_innov_var[axis_index]);
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}
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// if the innovation consistency check fails then don't fuse the sample
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if (_drag_test_ratio[axis_index] <= 1.0f) {
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// apply covariance correction via P_new = (I -K*H)*P
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// first calculate expression for KHP
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// then calculate P - KHP
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float KHP[_k_num_states][_k_num_states];
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float KH[9];
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for (unsigned row = 0; row < _k_num_states; row++) {
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KH[0] = Kfusion[row] * H_ACC[0];
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KH[1] = Kfusion[row] * H_ACC[1];
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KH[2] = Kfusion[row] * H_ACC[2];
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KH[3] = Kfusion[row] * H_ACC[3];
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KH[4] = Kfusion[row] * H_ACC[4];
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KH[5] = Kfusion[row] * H_ACC[5];
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KH[6] = Kfusion[row] * H_ACC[6];
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KH[7] = Kfusion[row] * H_ACC[22];
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KH[8] = Kfusion[row] * H_ACC[23];
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for (unsigned column = 0; column < _k_num_states; column++) {
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float tmp = KH[0] * P[0][column];
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tmp += KH[1] * P[1][column];
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tmp += KH[2] * P[2][column];
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tmp += KH[3] * P[3][column];
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tmp += KH[4] * P[4][column];
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tmp += KH[5] * P[5][column];
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tmp += KH[6] * P[6][column];
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tmp += KH[7] * P[22][column];
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tmp += KH[8] * P[23][column];
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KHP[row][column] = tmp;
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}
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}
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// if the covariance correction will result in a negative variance, then
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// the covariance matrix is unhealthy and must be corrected
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bool healthy = true;
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//_fault_status.flags.bad_sideslip = false;
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for (int i = 0; i < _k_num_states; i++) {
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if (P[i][i] < KHP[i][i]) {
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// zero rows and columns
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zeroRows(P, i, i);
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zeroCols(P, i, i);
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//flag as unhealthy
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healthy = false;
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// update individual measurement health status
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//_fault_status.flags.bad_sideslip = true;
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}
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}
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// only apply covariance and state corrections if healthy
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if (healthy) {
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// apply the covariance corrections
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for (unsigned row = 0; row < _k_num_states; row++) {
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for (unsigned column = 0; column < _k_num_states; column++) {
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P[row][column] = P[row][column] - KHP[row][column];
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}
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}
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// correct the covariance matrix for gross errors
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fixCovarianceErrors();
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// apply the state corrections
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fuse(Kfusion, _drag_innov[axis_index]);
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}
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}
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}
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}
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