#include #include "AP_NavEKF3.h" #include "AP_NavEKF3_core.h" #include #include #include extern const AP_HAL::HAL& hal; /******************************************************** * RESET FUNCTIONS * ********************************************************/ // Control reset of yaw and magnetic field states void NavEKF3_core::controlMagYawReset() { // Vehicles that can use a zero sideslip assumption (Planes) are a special case // They can use the GPS velocity to recover from bad initial compass data // This allows recovery for heading alignment errors due to compass faults if (assume_zero_sideslip() && !finalInflightYawInit && inFlight ) { gpsYawResetRequest = true; return; } else { gpsYawResetRequest = false; } // Quaternion and delta rotation vector that are re-used for different calculations Vector3f deltaRotVecTemp; Quaternion deltaQuatTemp; bool flightResetAllowed = false; bool initialResetAllowed = false; if (!finalInflightYawInit) { // Use a quaternion division to calculate the delta quaternion between the rotation at the current and last time deltaQuatTemp = stateStruct.quat / prevQuatMagReset; prevQuatMagReset = stateStruct.quat; // convert the quaternion to a rotation vector and find its length deltaQuatTemp.to_axis_angle(deltaRotVecTemp); // check if the spin rate is OK - high spin rates can cause angular alignment errors bool angRateOK = deltaRotVecTemp.length() < 0.1745f; initialResetAllowed = angRateOK; flightResetAllowed = angRateOK && !onGround; } // Check if conditions for a interim or final yaw/mag reset are met bool finalResetRequest = false; bool interimResetRequest = false; if (flightResetAllowed && !assume_zero_sideslip()) { // check that we have reached a height where ground magnetic interference effects are insignificant // and can perform a final reset of the yaw and field states finalResetRequest = (stateStruct.position.z - posDownAtTakeoff) < -EKF3_MAG_FINAL_RESET_ALT; // check for increasing height bool hgtIncreasing = (posDownAtLastMagReset-stateStruct.position.z) > 0.5f; float yawInnovIncrease = fabsf(innovYaw) - fabsf(yawInnovAtLastMagReset); // check for increasing yaw innovations bool yawInnovIncreasing = yawInnovIncrease > 0.25f; // check that the yaw innovations haven't been caused by a large change in attitude deltaQuatTemp = quatAtLastMagReset / stateStruct.quat; deltaQuatTemp.to_axis_angle(deltaRotVecTemp); bool largeAngleChange = deltaRotVecTemp.length() > yawInnovIncrease; // if yaw innovations and height have increased and we haven't rotated much // then we are climbing away from a ground based magnetic anomaly and need to reset interimResetRequest = hgtIncreasing && yawInnovIncreasing && !largeAngleChange; } // an initial reset is required if we have not yet aligned the yaw angle bool initialResetRequest = initialResetAllowed && !yawAlignComplete; // a combined yaw angle and magnetic field reset can be initiated by: magYawResetRequest = magYawResetRequest || // an external request initialResetRequest || // an initial alignment performed by all vehicle types using magnetometer interimResetRequest || // an interim alignment required to recover from ground based magnetic anomaly finalResetRequest; // the final reset when we have achieved enough height to be in stable magnetic field environment // Perform a reset of magnetic field states and reset yaw to corrected magnetic heading if (magYawResetRequest || magStateResetRequest) { // get the euler angles from the current state estimate Vector3f eulerAngles; stateStruct.quat.to_euler(eulerAngles.x, eulerAngles.y, eulerAngles.z); // Use the Euler angles and magnetometer measurement to update the magnetic field states // and get an updated quaternion Quaternion newQuat = calcQuatAndFieldStates(eulerAngles.x, eulerAngles.y); // if a yaw reset has been requested, apply the updated quaternion to the current state if (magYawResetRequest) { // previous value used to calculate a reset delta Quaternion prevQuat = stateStruct.quat; // calculate the variance for the rotation estimate expressed as a rotation vector // this will be used later to reset the quaternion state covariances Vector3f angleErrVarVec = calcRotVecVariances(); // update the quaternion states using the new yaw angle stateStruct.quat = newQuat; // update the yaw angle variance using the variance of the measurement angleErrVarVec.z = sq(MAX(frontend->_yawNoise, 1.0e-2f)); // reset the quaternion covariances using the rotation vector variances initialiseQuatCovariances(angleErrVarVec); // calculate the change in the quaternion state and apply it to the output history buffer prevQuat = stateStruct.quat/prevQuat; StoreQuatRotate(prevQuat); // send initial alignment status to console if (!yawAlignComplete) { gcs().send_text(MAV_SEVERITY_INFO, "EKF3 IMU%u initial yaw alignment complete",(unsigned)imu_index); } // send in-flight yaw alignment status to console if (finalResetRequest) { gcs().send_text(MAV_SEVERITY_INFO, "EKF3 IMU%u in-flight yaw alignment complete",(unsigned)imu_index); } else if (interimResetRequest) { gcs().send_text(MAV_SEVERITY_WARNING, "EKF3 IMU%u ground mag anomaly, yaw re-aligned",(unsigned)imu_index); } // prevent reset of variances in ConstrainVariances() inhibitMagStates = false; // update the yaw reset completed status recordYawReset(); // clear the yaw reset request flag magYawResetRequest = false; // clear the complete flags if an interim reset has been performed to allow subsequent // and final reset to occur if (interimResetRequest) { finalInflightYawInit = false; finalInflightMagInit = false; } } } } // this function is used to do a forced re-alignment of the yaw angle to align with the horizontal velocity // vector from GPS. It is used to align the yaw angle after launch or takeoff. void NavEKF3_core::realignYawGPS() { // get quaternion from existing filter states and calculate roll, pitch and yaw angles Vector3f eulerAngles; stateStruct.quat.to_euler(eulerAngles.x, eulerAngles.y, eulerAngles.z); if ((sq(gpsDataDelayed.vel.x) + sq(gpsDataDelayed.vel.y)) > 25.0f) { // calculate course yaw angle float velYaw = atan2f(stateStruct.velocity.y,stateStruct.velocity.x); // calculate course yaw angle from GPS velocity float gpsYaw = atan2f(gpsDataDelayed.vel.y,gpsDataDelayed.vel.x); // Check the yaw angles for consistency float yawErr = MAX(fabsf(wrap_PI(gpsYaw - velYaw)),fabsf(wrap_PI(gpsYaw - eulerAngles.z))); // If the angles disagree by more than 45 degrees and GPS innovations are large or no previous yaw alignment, we declare the magnetic yaw as bad badMagYaw = ((yawErr > 0.7854f) && (velTestRatio > 1.0f) && (PV_AidingMode == AID_ABSOLUTE)) || !yawAlignComplete; // correct yaw angle using GPS ground course if compass yaw bad if (badMagYaw) { // calculate the variance for the rotation estimate expressed as a rotation vector // this will be used later to reset the quaternion state covariances Vector3f angleErrVarVec = calcRotVecVariances(); // calculate new filter quaternion states from Euler angles stateStruct.quat.from_euler(eulerAngles.x, eulerAngles.y, gpsYaw); // reset the velocity and position states as they will be inaccurate due to bad yaw velResetSource = GPS; ResetVelocity(); posResetSource = GPS; ResetPosition(); // set the yaw angle variance to a larger value to reflect the uncertainty in yaw angleErrVarVec.z = sq(radians(45.0f)); // reset the quaternion covariances using the rotation vector variances zeroRows(P,0,3); zeroCols(P,0,3); initialiseQuatCovariances(angleErrVarVec); // send yaw alignment information to console gcs().send_text(MAV_SEVERITY_INFO, "EKF3 IMU%u yaw aligned to GPS velocity",(unsigned)imu_index); // record the yaw reset event recordYawReset(); // clear all pending yaw reset requests gpsYawResetRequest = false; magYawResetRequest = false; if (use_compass()) { // request a mag field reset which may enable us to use the magnetometer if the previous fault was due to bad initialisation magStateResetRequest = true; // clear the all sensors failed status so that the magnetometers sensors get a second chance now that we are flying allMagSensorsFailed = false; } } } } void NavEKF3_core::alignYawAngle() { // calculate the variance for the rotation estimate expressed as a rotation vector // this will be used later to reset the quaternion state covariances Vector3f angleErrVarVec = calcRotVecVariances(); if (yawAngDataDelayed.type == 2) { Vector3f euler321; stateStruct.quat.to_euler(euler321.x, euler321.y, euler321.z); stateStruct.quat.from_euler(euler321.x, euler321.y, yawAngDataDelayed.yawAng); } else if (yawAngDataDelayed.type == 1) { Vector3f euler312 = stateStruct.quat.to_vector312(); stateStruct.quat.from_vector312(euler312.x, euler312.y, yawAngDataDelayed.yawAng); } // set the yaw angle variance to a larger value to reflect the uncertainty in yaw angleErrVarVec.z = sq(yawAngDataDelayed.yawAngErr); // reset the quaternion covariances using the rotation vector variances zeroRows(P,0,3); zeroCols(P,0,3); initialiseQuatCovariances(angleErrVarVec); // send yaw alignment information to console gcs().send_text(MAV_SEVERITY_INFO, "EKF3 IMU%u yaw aligned",(unsigned)imu_index); // record the yaw reset event recordYawReset(); // clear any pending yaw reset requests gpsYawResetRequest = false; magYawResetRequest = false; } /******************************************************** * FUSE MEASURED_DATA * ********************************************************/ // select fusion of magnetometer data void NavEKF3_core::SelectMagFusion() { // start performance timer hal.util->perf_begin(_perf_FuseMagnetometer); // clear the flag that lets other processes know that the expensive magnetometer fusion operation has been performed on that time step // used for load levelling magFusePerformed = false; // Handle case where we are using an external yaw sensor instead of a magnetomer if ((frontend->_magCal == 5)) { if (storedYawAng.recall(yawAngDataDelayed,imuDataDelayed.time_ms)) { if (tiltAlignComplete && !yawAlignComplete) { alignYawAngle(); } else if (tiltAlignComplete && yawAlignComplete) { fuseEulerYaw(false, true); } else { fuseEulerYaw(true, true); } } return; } // check for and read new magnetometer measurements readMagData(); // If we are using the compass and the magnetometer has been unhealthy for too long we declare a timeout if (magHealth) { magTimeout = false; lastHealthyMagTime_ms = imuSampleTime_ms; } else if ((imuSampleTime_ms - lastHealthyMagTime_ms) > frontend->magFailTimeLimit_ms && use_compass()) { magTimeout = true; } // check for availability of magnetometer or other yaw data to fuse magDataToFuse = storedMag.recall(magDataDelayed,imuDataDelayed.time_ms); // Control reset of yaw and magnetic field states if we are using compass data if (magDataToFuse) { controlMagYawReset(); } // determine if conditions are right to start a new fusion cycle // wait until the EKF time horizon catches up with the measurement bool dataReady = (magDataToFuse && statesInitialised && use_compass() && yawAlignComplete); if (dataReady) { // use the simple method of declination to maintain heading if we cannot use the magnetic field states if(inhibitMagStates || magStateResetRequest || !magStateInitComplete) { fuseEulerYaw(false, false); // zero the test ratio output from the inactive 3-axis magnetometer fusion magTestRatio.zero(); } else { // if we are not doing aiding with earth relative observations (eg GPS) then the declination is // maintained by fusing declination as a synthesised observation if (PV_AidingMode != AID_ABSOLUTE) { FuseDeclination(0.34f); } // fuse the three magnetometer componenents sequentially hal.util->perf_begin(_perf_test[0]); for (mag_state.obsIndex = 0; mag_state.obsIndex <= 2; mag_state.obsIndex++) { FuseMagnetometer(); // don't continue fusion if unhealthy if (!magHealth) { hal.util->perf_end(_perf_test[0]); break; } } hal.util->perf_end(_perf_test[0]); // zero the test ratio output from the inactive simple magnetometer yaw fusion yawTestRatio = 0.0f; } } // If we have no magnetometer, fuse in a synthetic heading measurement at 7Hz to prevent the filter covariances // from becoming badly conditioned. For planes we only do this on-ground because they can align the yaw from GPS when // airborne. For other platform types we do this all the time. if (!use_compass()) { if ((onGround || !assume_zero_sideslip()) && (imuSampleTime_ms - lastSynthYawTime_ms > 140)) { fuseEulerYaw(true, false); magTestRatio.zero(); yawTestRatio = 0.0f; lastSynthYawTime_ms = imuSampleTime_ms; } } // If the final yaw reset has been performed and the state variances are sufficiently low // record that the earth field has been learned. if (!magFieldLearned && finalInflightMagInit) { magFieldLearned = (P[16][16] < sq(0.01f)) && (P[17][17] < sq(0.01f)) && (P[18][18] < sq(0.01f)); } // record the last learned field variances if (magFieldLearned && !inhibitMagStates) { earthMagFieldVar.x = P[16][16]; earthMagFieldVar.y = P[17][17]; earthMagFieldVar.z = P[18][18]; bodyMagFieldVar.x = P[19][19]; bodyMagFieldVar.y = P[20][20]; bodyMagFieldVar.z = P[21][21]; } // stop performance timer hal.util->perf_end(_perf_FuseMagnetometer); } /* * Fuse magnetometer measurements using explicit algebraic equations generated with Matlab symbolic toolbox. * The script file used to generate these and other equations in this filter can be found here: * https://github.com/PX4/ecl/blob/master/matlab/scripts/Inertial%20Nav%20EKF/GenerateNavFilterEquations.m */ void NavEKF3_core::FuseMagnetometer() { // declarations ftype &q0 = mag_state.q0; ftype &q1 = mag_state.q1; ftype &q2 = mag_state.q2; ftype &q3 = mag_state.q3; ftype &magN = mag_state.magN; ftype &magE = mag_state.magE; ftype &magD = mag_state.magD; ftype &magXbias = mag_state.magXbias; ftype &magYbias = mag_state.magYbias; ftype &magZbias = mag_state.magZbias; uint8_t &obsIndex = mag_state.obsIndex; Matrix3f &DCM = mag_state.DCM; Vector3f &MagPred = mag_state.MagPred; ftype &R_MAG = mag_state.R_MAG; ftype *SH_MAG = &mag_state.SH_MAG[0]; Vector24 H_MAG; Vector5 SK_MX; Vector5 SK_MY; Vector5 SK_MZ; // perform sequential fusion of magnetometer measurements. // this assumes that the errors in the different components are // uncorrelated which is not true, however in the absence of covariance // data fit is the only assumption we can make // so we might as well take advantage of the computational efficiencies // associated with sequential fusion // calculate observation jacobians and Kalman gains // copy required states to local variable names q0 = stateStruct.quat[0]; q1 = stateStruct.quat[1]; q2 = stateStruct.quat[2]; q3 = stateStruct.quat[3]; magN = stateStruct.earth_magfield[0]; magE = stateStruct.earth_magfield[1]; magD = stateStruct.earth_magfield[2]; magXbias = stateStruct.body_magfield[0]; magYbias = stateStruct.body_magfield[1]; magZbias = stateStruct.body_magfield[2]; // rotate predicted earth components into body axes and calculate // predicted measurements DCM[0][0] = q0*q0 + q1*q1 - q2*q2 - q3*q3; DCM[0][1] = 2.0f*(q1*q2 + q0*q3); DCM[0][2] = 2.0f*(q1*q3-q0*q2); DCM[1][0] = 2.0f*(q1*q2 - q0*q3); DCM[1][1] = q0*q0 - q1*q1 + q2*q2 - q3*q3; DCM[1][2] = 2.0f*(q2*q3 + q0*q1); DCM[2][0] = 2.0f*(q1*q3 + q0*q2); DCM[2][1] = 2.0f*(q2*q3 - q0*q1); DCM[2][2] = q0*q0 - q1*q1 - q2*q2 + q3*q3; MagPred[0] = DCM[0][0]*magN + DCM[0][1]*magE + DCM[0][2]*magD + magXbias; MagPred[1] = DCM[1][0]*magN + DCM[1][1]*magE + DCM[1][2]*magD + magYbias; MagPred[2] = DCM[2][0]*magN + DCM[2][1]*magE + DCM[2][2]*magD + magZbias; // calculate the measurement innovation for each axis for (uint8_t i = 0; i<=2; i++) { innovMag[i] = MagPred[i] - magDataDelayed.mag[i]; } // scale magnetometer observation error with total angular rate to allow for timing errors R_MAG = sq(constrain_float(frontend->_magNoise, 0.01f, 0.5f)) + sq(frontend->magVarRateScale*imuDataDelayed.delAng.length() / imuDataDelayed.delAngDT); // calculate common expressions used to calculate observation jacobians an innovation variance for each component SH_MAG[0] = 2.0f*magD*q3 + 2.0f*magE*q2 + 2.0f*magN*q1; SH_MAG[1] = 2.0f*magD*q0 - 2.0f*magE*q1 + 2.0f*magN*q2; SH_MAG[2] = 2.0f*magD*q1 + 2.0f*magE*q0 - 2.0f*magN*q3; SH_MAG[3] = sq(q3); SH_MAG[4] = sq(q2); SH_MAG[5] = sq(q1); SH_MAG[6] = sq(q0); SH_MAG[7] = 2.0f*magN*q0; SH_MAG[8] = 2.0f*magE*q3; // Calculate the innovation variance for each axis // X axis varInnovMag[0] = (P[19][19] + R_MAG + P[1][19]*SH_MAG[0] - P[2][19]*SH_MAG[1] + P[3][19]*SH_MAG[2] - P[16][19]*(SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6]) + (2.0f*q0*q3 + 2.0f*q1*q2)*(P[19][17] + P[1][17]*SH_MAG[0] - P[2][17]*SH_MAG[1] + P[3][17]*SH_MAG[2] - P[16][17]*(SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6]) + P[17][17]*(2.0f*q0*q3 + 2.0f*q1*q2) - P[18][17]*(2.0f*q0*q2 - 2.0f*q1*q3) + P[0][17]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) - (2.0f*q0*q2 - 2.0f*q1*q3)*(P[19][18] + P[1][18]*SH_MAG[0] - P[2][18]*SH_MAG[1] + P[3][18]*SH_MAG[2] - P[16][18]*(SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6]) + P[17][18]*(2.0f*q0*q3 + 2.0f*q1*q2) - P[18][18]*(2.0f*q0*q2 - 2.0f*q1*q3) + P[0][18]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + (SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)*(P[19][0] + P[1][0]*SH_MAG[0] - P[2][0]*SH_MAG[1] + P[3][0]*SH_MAG[2] - P[16][0]*(SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6]) + P[17][0]*(2.0f*q0*q3 + 2.0f*q1*q2) - P[18][0]*(2.0f*q0*q2 - 2.0f*q1*q3) + P[0][0]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + P[17][19]*(2.0f*q0*q3 + 2.0f*q1*q2) - P[18][19]*(2.0f*q0*q2 - 2.0f*q1*q3) + SH_MAG[0]*(P[19][1] + P[1][1]*SH_MAG[0] - P[2][1]*SH_MAG[1] + P[3][1]*SH_MAG[2] - P[16][1]*(SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6]) + P[17][1]*(2.0f*q0*q3 + 2.0f*q1*q2) - P[18][1]*(2.0f*q0*q2 - 2.0f*q1*q3) + P[0][1]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) - SH_MAG[1]*(P[19][2] + P[1][2]*SH_MAG[0] - P[2][2]*SH_MAG[1] + P[3][2]*SH_MAG[2] - P[16][2]*(SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6]) + P[17][2]*(2.0f*q0*q3 + 2.0f*q1*q2) - P[18][2]*(2.0f*q0*q2 - 2.0f*q1*q3) + P[0][2]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + SH_MAG[2]*(P[19][3] + P[1][3]*SH_MAG[0] - P[2][3]*SH_MAG[1] + P[3][3]*SH_MAG[2] - P[16][3]*(SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6]) + P[17][3]*(2.0f*q0*q3 + 2.0f*q1*q2) - P[18][3]*(2.0f*q0*q2 - 2.0f*q1*q3) + P[0][3]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) - (SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6])*(P[19][16] + P[1][16]*SH_MAG[0] - P[2][16]*SH_MAG[1] + P[3][16]*SH_MAG[2] - P[16][16]*(SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6]) + P[17][16]*(2.0f*q0*q3 + 2.0f*q1*q2) - P[18][16]*(2.0f*q0*q2 - 2.0f*q1*q3) + P[0][16]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + P[0][19]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)); if (varInnovMag[0] >= R_MAG) { faultStatus.bad_xmag = false; } else { // the calculation is badly conditioned, so we cannot perform fusion on this step // we reset the covariance matrix and try again next measurement CovarianceInit(); faultStatus.bad_xmag = true; return; } // Y axis varInnovMag[1] = (P[20][20] + R_MAG + P[0][20]*SH_MAG[2] + P[1][20]*SH_MAG[1] + P[2][20]*SH_MAG[0] - P[17][20]*(SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6]) - (2.0f*q0*q3 - 2.0f*q1*q2)*(P[20][16] + P[0][16]*SH_MAG[2] + P[1][16]*SH_MAG[1] + P[2][16]*SH_MAG[0] - P[17][16]*(SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6]) - P[16][16]*(2.0f*q0*q3 - 2.0f*q1*q2) + P[18][16]*(2.0f*q0*q1 + 2.0f*q2*q3) - P[3][16]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + (2.0f*q0*q1 + 2.0f*q2*q3)*(P[20][18] + P[0][18]*SH_MAG[2] + P[1][18]*SH_MAG[1] + P[2][18]*SH_MAG[0] - P[17][18]*(SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6]) - P[16][18]*(2.0f*q0*q3 - 2.0f*q1*q2) + P[18][18]*(2.0f*q0*q1 + 2.0f*q2*q3) - P[3][18]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) - (SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)*(P[20][3] + P[0][3]*SH_MAG[2] + P[1][3]*SH_MAG[1] + P[2][3]*SH_MAG[0] - P[17][3]*(SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6]) - P[16][3]*(2.0f*q0*q3 - 2.0f*q1*q2) + P[18][3]*(2.0f*q0*q1 + 2.0f*q2*q3) - P[3][3]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) - P[16][20]*(2.0f*q0*q3 - 2.0f*q1*q2) + P[18][20]*(2.0f*q0*q1 + 2.0f*q2*q3) + SH_MAG[2]*(P[20][0] + P[0][0]*SH_MAG[2] + P[1][0]*SH_MAG[1] + P[2][0]*SH_MAG[0] - P[17][0]*(SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6]) - P[16][0]*(2.0f*q0*q3 - 2.0f*q1*q2) + P[18][0]*(2.0f*q0*q1 + 2.0f*q2*q3) - P[3][0]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + SH_MAG[1]*(P[20][1] + P[0][1]*SH_MAG[2] + P[1][1]*SH_MAG[1] + P[2][1]*SH_MAG[0] - P[17][1]*(SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6]) - P[16][1]*(2.0f*q0*q3 - 2.0f*q1*q2) + P[18][1]*(2.0f*q0*q1 + 2.0f*q2*q3) - P[3][1]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + SH_MAG[0]*(P[20][2] + P[0][2]*SH_MAG[2] + P[1][2]*SH_MAG[1] + P[2][2]*SH_MAG[0] - P[17][2]*(SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6]) - P[16][2]*(2.0f*q0*q3 - 2.0f*q1*q2) + P[18][2]*(2.0f*q0*q1 + 2.0f*q2*q3) - P[3][2]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) - (SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6])*(P[20][17] + P[0][17]*SH_MAG[2] + P[1][17]*SH_MAG[1] + P[2][17]*SH_MAG[0] - P[17][17]*(SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6]) - P[16][17]*(2.0f*q0*q3 - 2.0f*q1*q2) + P[18][17]*(2.0f*q0*q1 + 2.0f*q2*q3) - P[3][17]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) - P[3][20]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)); if (varInnovMag[1] >= R_MAG) { faultStatus.bad_ymag = false; } else { // the calculation is badly conditioned, so we cannot perform fusion on this step // we reset the covariance matrix and try again next measurement CovarianceInit(); faultStatus.bad_ymag = true; return; } // Z axis varInnovMag[2] = (P[21][21] + R_MAG + P[0][21]*SH_MAG[1] - P[1][21]*SH_MAG[2] + P[3][21]*SH_MAG[0] + P[18][21]*(SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]) + (2.0f*q0*q2 + 2.0f*q1*q3)*(P[21][16] + P[0][16]*SH_MAG[1] - P[1][16]*SH_MAG[2] + P[3][16]*SH_MAG[0] + P[18][16]*(SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]) + P[16][16]*(2.0f*q0*q2 + 2.0f*q1*q3) - P[17][16]*(2.0f*q0*q1 - 2.0f*q2*q3) + P[2][16]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) - (2.0f*q0*q1 - 2.0f*q2*q3)*(P[21][17] + P[0][17]*SH_MAG[1] - P[1][17]*SH_MAG[2] + P[3][17]*SH_MAG[0] + P[18][17]*(SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]) + P[16][17]*(2.0f*q0*q2 + 2.0f*q1*q3) - P[17][17]*(2.0f*q0*q1 - 2.0f*q2*q3) + P[2][17]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + (SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)*(P[21][2] + P[0][2]*SH_MAG[1] - P[1][2]*SH_MAG[2] + P[3][2]*SH_MAG[0] + P[18][2]*(SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]) + P[16][2]*(2.0f*q0*q2 + 2.0f*q1*q3) - P[17][2]*(2.0f*q0*q1 - 2.0f*q2*q3) + P[2][2]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + P[16][21]*(2.0f*q0*q2 + 2.0f*q1*q3) - P[17][21]*(2.0f*q0*q1 - 2.0f*q2*q3) + SH_MAG[1]*(P[21][0] + P[0][0]*SH_MAG[1] - P[1][0]*SH_MAG[2] + P[3][0]*SH_MAG[0] + P[18][0]*(SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]) + P[16][0]*(2.0f*q0*q2 + 2.0f*q1*q3) - P[17][0]*(2.0f*q0*q1 - 2.0f*q2*q3) + P[2][0]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) - SH_MAG[2]*(P[21][1] + P[0][1]*SH_MAG[1] - P[1][1]*SH_MAG[2] + P[3][1]*SH_MAG[0] + P[18][1]*(SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]) + P[16][1]*(2.0f*q0*q2 + 2.0f*q1*q3) - P[17][1]*(2.0f*q0*q1 - 2.0f*q2*q3) + P[2][1]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + SH_MAG[0]*(P[21][3] + P[0][3]*SH_MAG[1] - P[1][3]*SH_MAG[2] + P[3][3]*SH_MAG[0] + P[18][3]*(SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]) + P[16][3]*(2.0f*q0*q2 + 2.0f*q1*q3) - P[17][3]*(2.0f*q0*q1 - 2.0f*q2*q3) + P[2][3]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + (SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6])*(P[21][18] + P[0][18]*SH_MAG[1] - P[1][18]*SH_MAG[2] + P[3][18]*SH_MAG[0] + P[18][18]*(SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]) + P[16][18]*(2.0f*q0*q2 + 2.0f*q1*q3) - P[17][18]*(2.0f*q0*q1 - 2.0f*q2*q3) + P[2][18]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)) + P[2][21]*(SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2)); if (varInnovMag[2] >= R_MAG) { faultStatus.bad_zmag = false; } else { // the calculation is badly conditioned, so we cannot perform fusion on this step // we reset the covariance matrix and try again next measurement CovarianceInit(); faultStatus.bad_zmag = true; return; } // calculate the innovation test ratios for (uint8_t i = 0; i<=2; i++) { magTestRatio[i] = sq(innovMag[i]) / (sq(MAX(0.01f * (float)frontend->_magInnovGate, 1.0f)) * varInnovMag[i]); } // check the last values from all components and set magnetometer health accordingly magHealth = (magTestRatio[0] < 1.0f && magTestRatio[1] < 1.0f && magTestRatio[2] < 1.0f); // if the magnetometer is unhealthy, do not proceed further if (!magHealth) { return; } for (obsIndex = 0; obsIndex <= 2; obsIndex++) { if (obsIndex == 0) { for (uint8_t i = 0; i<=stateIndexLim; i++) H_MAG[i] = 0.0f; H_MAG[0] = SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2; H_MAG[1] = SH_MAG[0]; H_MAG[2] = -SH_MAG[1]; H_MAG[3] = SH_MAG[2]; H_MAG[16] = SH_MAG[5] - SH_MAG[4] - SH_MAG[3] + SH_MAG[6]; H_MAG[17] = 2.0f*q0*q3 + 2.0f*q1*q2; H_MAG[18] = 2.0f*q1*q3 - 2.0f*q0*q2; H_MAG[19] = 1.0f; H_MAG[20] = 0.0f; H_MAG[21] = 0.0f; // calculate Kalman gain SK_MX[0] = 1.0f / varInnovMag[0]; SK_MX[1] = SH_MAG[3] + SH_MAG[4] - SH_MAG[5] - SH_MAG[6]; SK_MX[2] = SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2; SK_MX[3] = 2.0f*q0*q2 - 2.0f*q1*q3; SK_MX[4] = 2.0f*q0*q3 + 2.0f*q1*q2; Kfusion[0] = SK_MX[0]*(P[0][19] + P[0][1]*SH_MAG[0] - P[0][2]*SH_MAG[1] + P[0][3]*SH_MAG[2] + P[0][0]*SK_MX[2] - P[0][16]*SK_MX[1] + P[0][17]*SK_MX[4] - P[0][18]*SK_MX[3]); Kfusion[1] = SK_MX[0]*(P[1][19] + P[1][1]*SH_MAG[0] - P[1][2]*SH_MAG[1] + P[1][3]*SH_MAG[2] + P[1][0]*SK_MX[2] - P[1][16]*SK_MX[1] + P[1][17]*SK_MX[4] - P[1][18]*SK_MX[3]); Kfusion[2] = SK_MX[0]*(P[2][19] + P[2][1]*SH_MAG[0] - P[2][2]*SH_MAG[1] + P[2][3]*SH_MAG[2] + P[2][0]*SK_MX[2] - P[2][16]*SK_MX[1] + P[2][17]*SK_MX[4] - P[2][18]*SK_MX[3]); Kfusion[3] = SK_MX[0]*(P[3][19] + P[3][1]*SH_MAG[0] - P[3][2]*SH_MAG[1] + P[3][3]*SH_MAG[2] + P[3][0]*SK_MX[2] - P[3][16]*SK_MX[1] + P[3][17]*SK_MX[4] - P[3][18]*SK_MX[3]); Kfusion[4] = SK_MX[0]*(P[4][19] + P[4][1]*SH_MAG[0] - P[4][2]*SH_MAG[1] + P[4][3]*SH_MAG[2] + P[4][0]*SK_MX[2] - P[4][16]*SK_MX[1] + P[4][17]*SK_MX[4] - P[4][18]*SK_MX[3]); Kfusion[5] = SK_MX[0]*(P[5][19] + P[5][1]*SH_MAG[0] - P[5][2]*SH_MAG[1] + P[5][3]*SH_MAG[2] + P[5][0]*SK_MX[2] - P[5][16]*SK_MX[1] + P[5][17]*SK_MX[4] - P[5][18]*SK_MX[3]); Kfusion[6] = SK_MX[0]*(P[6][19] + P[6][1]*SH_MAG[0] - P[6][2]*SH_MAG[1] + P[6][3]*SH_MAG[2] + P[6][0]*SK_MX[2] - P[6][16]*SK_MX[1] + P[6][17]*SK_MX[4] - P[6][18]*SK_MX[3]); Kfusion[7] = SK_MX[0]*(P[7][19] + P[7][1]*SH_MAG[0] - P[7][2]*SH_MAG[1] + P[7][3]*SH_MAG[2] + P[7][0]*SK_MX[2] - P[7][16]*SK_MX[1] + P[7][17]*SK_MX[4] - P[7][18]*SK_MX[3]); Kfusion[8] = SK_MX[0]*(P[8][19] + P[8][1]*SH_MAG[0] - P[8][2]*SH_MAG[1] + P[8][3]*SH_MAG[2] + P[8][0]*SK_MX[2] - P[8][16]*SK_MX[1] + P[8][17]*SK_MX[4] - P[8][18]*SK_MX[3]); Kfusion[9] = SK_MX[0]*(P[9][19] + P[9][1]*SH_MAG[0] - P[9][2]*SH_MAG[1] + P[9][3]*SH_MAG[2] + P[9][0]*SK_MX[2] - P[9][16]*SK_MX[1] + P[9][17]*SK_MX[4] - P[9][18]*SK_MX[3]); if (!inhibitDelAngBiasStates) { Kfusion[10] = SK_MX[0]*(P[10][19] + P[10][1]*SH_MAG[0] - P[10][2]*SH_MAG[1] + P[10][3]*SH_MAG[2] + P[10][0]*SK_MX[2] - P[10][16]*SK_MX[1] + P[10][17]*SK_MX[4] - P[10][18]*SK_MX[3]); Kfusion[11] = SK_MX[0]*(P[11][19] + P[11][1]*SH_MAG[0] - P[11][2]*SH_MAG[1] + P[11][3]*SH_MAG[2] + P[11][0]*SK_MX[2] - P[11][16]*SK_MX[1] + P[11][17]*SK_MX[4] - P[11][18]*SK_MX[3]); Kfusion[12] = SK_MX[0]*(P[12][19] + P[12][1]*SH_MAG[0] - P[12][2]*SH_MAG[1] + P[12][3]*SH_MAG[2] + P[12][0]*SK_MX[2] - P[12][16]*SK_MX[1] + P[12][17]*SK_MX[4] - P[12][18]*SK_MX[3]); } else { // zero indexes 10 to 12 = 3*4 bytes memset(&Kfusion[10], 0, 12); } if (!inhibitDelVelBiasStates) { Kfusion[13] = SK_MX[0]*(P[13][19] + P[13][1]*SH_MAG[0] - P[13][2]*SH_MAG[1] + P[13][3]*SH_MAG[2] + P[13][0]*SK_MX[2] - P[13][16]*SK_MX[1] + P[13][17]*SK_MX[4] - P[13][18]*SK_MX[3]); Kfusion[14] = SK_MX[0]*(P[14][19] + P[14][1]*SH_MAG[0] - P[14][2]*SH_MAG[1] + P[14][3]*SH_MAG[2] + P[14][0]*SK_MX[2] - P[14][16]*SK_MX[1] + P[14][17]*SK_MX[4] - P[14][18]*SK_MX[3]); Kfusion[15] = SK_MX[0]*(P[15][19] + P[15][1]*SH_MAG[0] - P[15][2]*SH_MAG[1] + P[15][3]*SH_MAG[2] + P[15][0]*SK_MX[2] - P[15][16]*SK_MX[1] + P[15][17]*SK_MX[4] - P[15][18]*SK_MX[3]); } else { // zero indexes 13 to 15 = 3*4 bytes memset(&Kfusion[13], 0, 12); } // zero Kalman gains to inhibit magnetic field state estimation if (!inhibitMagStates) { Kfusion[16] = SK_MX[0]*(P[16][19] + P[16][1]*SH_MAG[0] - P[16][2]*SH_MAG[1] + P[16][3]*SH_MAG[2] + P[16][0]*SK_MX[2] - P[16][16]*SK_MX[1] + P[16][17]*SK_MX[4] - P[16][18]*SK_MX[3]); Kfusion[17] = SK_MX[0]*(P[17][19] + P[17][1]*SH_MAG[0] - P[17][2]*SH_MAG[1] + P[17][3]*SH_MAG[2] + P[17][0]*SK_MX[2] - P[17][16]*SK_MX[1] + P[17][17]*SK_MX[4] - P[17][18]*SK_MX[3]); Kfusion[18] = SK_MX[0]*(P[18][19] + P[18][1]*SH_MAG[0] - P[18][2]*SH_MAG[1] + P[18][3]*SH_MAG[2] + P[18][0]*SK_MX[2] - P[18][16]*SK_MX[1] + P[18][17]*SK_MX[4] - P[18][18]*SK_MX[3]); Kfusion[19] = SK_MX[0]*(P[19][19] + P[19][1]*SH_MAG[0] - P[19][2]*SH_MAG[1] + P[19][3]*SH_MAG[2] + P[19][0]*SK_MX[2] - P[19][16]*SK_MX[1] + P[19][17]*SK_MX[4] - P[19][18]*SK_MX[3]); Kfusion[20] = SK_MX[0]*(P[20][19] + P[20][1]*SH_MAG[0] - P[20][2]*SH_MAG[1] + P[20][3]*SH_MAG[2] + P[20][0]*SK_MX[2] - P[20][16]*SK_MX[1] + P[20][17]*SK_MX[4] - P[20][18]*SK_MX[3]); Kfusion[21] = SK_MX[0]*(P[21][19] + P[21][1]*SH_MAG[0] - P[21][2]*SH_MAG[1] + P[21][3]*SH_MAG[2] + P[21][0]*SK_MX[2] - P[21][16]*SK_MX[1] + P[21][17]*SK_MX[4] - P[21][18]*SK_MX[3]); } else { // zero indexes 16 to 21 = 6*4 bytes memset(&Kfusion[16], 0, 24); } // zero Kalman gains to inhibit wind state estimation if (!inhibitWindStates) { Kfusion[22] = SK_MX[0]*(P[22][19] + P[22][1]*SH_MAG[0] - P[22][2]*SH_MAG[1] + P[22][3]*SH_MAG[2] + P[22][0]*SK_MX[2] - P[22][16]*SK_MX[1] + P[22][17]*SK_MX[4] - P[22][18]*SK_MX[3]); Kfusion[23] = SK_MX[0]*(P[23][19] + P[23][1]*SH_MAG[0] - P[23][2]*SH_MAG[1] + P[23][3]*SH_MAG[2] + P[23][0]*SK_MX[2] - P[23][16]*SK_MX[1] + P[23][17]*SK_MX[4] - P[23][18]*SK_MX[3]); } else { // zero indexes 22 to 23 = 2*4 bytes memset(&Kfusion[22], 0, 8); } // set flags to indicate to other processes that fusion has been performed and is required on the next frame // this can be used by other fusion processes to avoid fusing on the same frame as this expensive step magFusePerformed = true; magFuseRequired = true; } else if (obsIndex == 1) { // Fuse Y axis // calculate observation jacobians for (uint8_t i = 0; i<=stateIndexLim; i++) H_MAG[i] = 0.0f; H_MAG[0] = SH_MAG[2]; H_MAG[1] = SH_MAG[1]; H_MAG[2] = SH_MAG[0]; H_MAG[3] = 2.0f*magD*q2 - SH_MAG[8] - SH_MAG[7]; H_MAG[16] = 2.0f*q1*q2 - 2.0f*q0*q3; H_MAG[17] = SH_MAG[4] - SH_MAG[3] - SH_MAG[5] + SH_MAG[6]; H_MAG[18] = 2.0f*q0*q1 + 2.0f*q2*q3; H_MAG[19] = 0.0f; H_MAG[20] = 1.0f; H_MAG[21] = 0.0f; // calculate Kalman gain SK_MY[0] = 1.0f / varInnovMag[1]; SK_MY[1] = SH_MAG[3] - SH_MAG[4] + SH_MAG[5] - SH_MAG[6]; SK_MY[2] = SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2; SK_MY[3] = 2.0f*q0*q3 - 2.0f*q1*q2; SK_MY[4] = 2.0f*q0*q1 + 2.0f*q2*q3; Kfusion[0] = SK_MY[0]*(P[0][20] + P[0][0]*SH_MAG[2] + P[0][1]*SH_MAG[1] + P[0][2]*SH_MAG[0] - P[0][3]*SK_MY[2] - P[0][17]*SK_MY[1] - P[0][16]*SK_MY[3] + P[0][18]*SK_MY[4]); Kfusion[1] = SK_MY[0]*(P[1][20] + P[1][0]*SH_MAG[2] + P[1][1]*SH_MAG[1] + P[1][2]*SH_MAG[0] - P[1][3]*SK_MY[2] - P[1][17]*SK_MY[1] - P[1][16]*SK_MY[3] + P[1][18]*SK_MY[4]); Kfusion[2] = SK_MY[0]*(P[2][20] + P[2][0]*SH_MAG[2] + P[2][1]*SH_MAG[1] + P[2][2]*SH_MAG[0] - P[2][3]*SK_MY[2] - P[2][17]*SK_MY[1] - P[2][16]*SK_MY[3] + P[2][18]*SK_MY[4]); Kfusion[3] = SK_MY[0]*(P[3][20] + P[3][0]*SH_MAG[2] + P[3][1]*SH_MAG[1] + P[3][2]*SH_MAG[0] - P[3][3]*SK_MY[2] - P[3][17]*SK_MY[1] - P[3][16]*SK_MY[3] + P[3][18]*SK_MY[4]); Kfusion[4] = SK_MY[0]*(P[4][20] + P[4][0]*SH_MAG[2] + P[4][1]*SH_MAG[1] + P[4][2]*SH_MAG[0] - P[4][3]*SK_MY[2] - P[4][17]*SK_MY[1] - P[4][16]*SK_MY[3] + P[4][18]*SK_MY[4]); Kfusion[5] = SK_MY[0]*(P[5][20] + P[5][0]*SH_MAG[2] + P[5][1]*SH_MAG[1] + P[5][2]*SH_MAG[0] - P[5][3]*SK_MY[2] - P[5][17]*SK_MY[1] - P[5][16]*SK_MY[3] + P[5][18]*SK_MY[4]); Kfusion[6] = SK_MY[0]*(P[6][20] + P[6][0]*SH_MAG[2] + P[6][1]*SH_MAG[1] + P[6][2]*SH_MAG[0] - P[6][3]*SK_MY[2] - P[6][17]*SK_MY[1] - P[6][16]*SK_MY[3] + P[6][18]*SK_MY[4]); Kfusion[7] = SK_MY[0]*(P[7][20] + P[7][0]*SH_MAG[2] + P[7][1]*SH_MAG[1] + P[7][2]*SH_MAG[0] - P[7][3]*SK_MY[2] - P[7][17]*SK_MY[1] - P[7][16]*SK_MY[3] + P[7][18]*SK_MY[4]); Kfusion[8] = SK_MY[0]*(P[8][20] + P[8][0]*SH_MAG[2] + P[8][1]*SH_MAG[1] + P[8][2]*SH_MAG[0] - P[8][3]*SK_MY[2] - P[8][17]*SK_MY[1] - P[8][16]*SK_MY[3] + P[8][18]*SK_MY[4]); Kfusion[9] = SK_MY[0]*(P[9][20] + P[9][0]*SH_MAG[2] + P[9][1]*SH_MAG[1] + P[9][2]*SH_MAG[0] - P[9][3]*SK_MY[2] - P[9][17]*SK_MY[1] - P[9][16]*SK_MY[3] + P[9][18]*SK_MY[4]); if (!inhibitDelAngBiasStates) { Kfusion[10] = SK_MY[0]*(P[10][20] + P[10][0]*SH_MAG[2] + P[10][1]*SH_MAG[1] + P[10][2]*SH_MAG[0] - P[10][3]*SK_MY[2] - P[10][17]*SK_MY[1] - P[10][16]*SK_MY[3] + P[10][18]*SK_MY[4]); Kfusion[11] = SK_MY[0]*(P[11][20] + P[11][0]*SH_MAG[2] + P[11][1]*SH_MAG[1] + P[11][2]*SH_MAG[0] - P[11][3]*SK_MY[2] - P[11][17]*SK_MY[1] - P[11][16]*SK_MY[3] + P[11][18]*SK_MY[4]); Kfusion[12] = SK_MY[0]*(P[12][20] + P[12][0]*SH_MAG[2] + P[12][1]*SH_MAG[1] + P[12][2]*SH_MAG[0] - P[12][3]*SK_MY[2] - P[12][17]*SK_MY[1] - P[12][16]*SK_MY[3] + P[12][18]*SK_MY[4]); } else { // zero indexes 10 to 12 = 3*4 bytes memset(&Kfusion[10], 0, 12); } if (!inhibitDelVelBiasStates) { Kfusion[13] = SK_MY[0]*(P[13][20] + P[13][0]*SH_MAG[2] + P[13][1]*SH_MAG[1] + P[13][2]*SH_MAG[0] - P[13][3]*SK_MY[2] - P[13][17]*SK_MY[1] - P[13][16]*SK_MY[3] + P[13][18]*SK_MY[4]); Kfusion[14] = SK_MY[0]*(P[14][20] + P[14][0]*SH_MAG[2] + P[14][1]*SH_MAG[1] + P[14][2]*SH_MAG[0] - P[14][3]*SK_MY[2] - P[14][17]*SK_MY[1] - P[14][16]*SK_MY[3] + P[14][18]*SK_MY[4]); Kfusion[15] = SK_MY[0]*(P[15][20] + P[15][0]*SH_MAG[2] + P[15][1]*SH_MAG[1] + P[15][2]*SH_MAG[0] - P[15][3]*SK_MY[2] - P[15][17]*SK_MY[1] - P[15][16]*SK_MY[3] + P[15][18]*SK_MY[4]); } else { // zero indexes 13 to 15 = 3*4 bytes memset(&Kfusion[13], 0, 12); } // zero Kalman gains to inhibit magnetic field state estimation if (!inhibitMagStates) { Kfusion[16] = SK_MY[0]*(P[16][20] + P[16][0]*SH_MAG[2] + P[16][1]*SH_MAG[1] + P[16][2]*SH_MAG[0] - P[16][3]*SK_MY[2] - P[16][17]*SK_MY[1] - P[16][16]*SK_MY[3] + P[16][18]*SK_MY[4]); Kfusion[17] = SK_MY[0]*(P[17][20] + P[17][0]*SH_MAG[2] + P[17][1]*SH_MAG[1] + P[17][2]*SH_MAG[0] - P[17][3]*SK_MY[2] - P[17][17]*SK_MY[1] - P[17][16]*SK_MY[3] + P[17][18]*SK_MY[4]); Kfusion[18] = SK_MY[0]*(P[18][20] + P[18][0]*SH_MAG[2] + P[18][1]*SH_MAG[1] + P[18][2]*SH_MAG[0] - P[18][3]*SK_MY[2] - P[18][17]*SK_MY[1] - P[18][16]*SK_MY[3] + P[18][18]*SK_MY[4]); Kfusion[19] = SK_MY[0]*(P[19][20] + P[19][0]*SH_MAG[2] + P[19][1]*SH_MAG[1] + P[19][2]*SH_MAG[0] - P[19][3]*SK_MY[2] - P[19][17]*SK_MY[1] - P[19][16]*SK_MY[3] + P[19][18]*SK_MY[4]); Kfusion[20] = SK_MY[0]*(P[20][20] + P[20][0]*SH_MAG[2] + P[20][1]*SH_MAG[1] + P[20][2]*SH_MAG[0] - P[20][3]*SK_MY[2] - P[20][17]*SK_MY[1] - P[20][16]*SK_MY[3] + P[20][18]*SK_MY[4]); Kfusion[21] = SK_MY[0]*(P[21][20] + P[21][0]*SH_MAG[2] + P[21][1]*SH_MAG[1] + P[21][2]*SH_MAG[0] - P[21][3]*SK_MY[2] - P[21][17]*SK_MY[1] - P[21][16]*SK_MY[3] + P[21][18]*SK_MY[4]); } else { // zero indexes 16 to 21 = 6*4 bytes memset(&Kfusion[16], 0, 24); } // zero Kalman gains to inhibit wind state estimation if (!inhibitWindStates) { Kfusion[22] = SK_MY[0]*(P[22][20] + P[22][0]*SH_MAG[2] + P[22][1]*SH_MAG[1] + P[22][2]*SH_MAG[0] - P[22][3]*SK_MY[2] - P[22][17]*SK_MY[1] - P[22][16]*SK_MY[3] + P[22][18]*SK_MY[4]); Kfusion[23] = SK_MY[0]*(P[23][20] + P[23][0]*SH_MAG[2] + P[23][1]*SH_MAG[1] + P[23][2]*SH_MAG[0] - P[23][3]*SK_MY[2] - P[23][17]*SK_MY[1] - P[23][16]*SK_MY[3] + P[23][18]*SK_MY[4]); } else { // zero indexes 22 to 23 = 2*4 bytes memset(&Kfusion[22], 0, 8); } // set flags to indicate to other processes that fusion has been performed and is required on the next frame // this can be used by other fusion processes to avoid fusing on the same frame as this expensive step magFusePerformed = true; magFuseRequired = true; } else if (obsIndex == 2) // we are now fusing the Z measurement { // calculate observation jacobians for (uint8_t i = 0; i<=stateIndexLim; i++) H_MAG[i] = 0.0f; H_MAG[0] = SH_MAG[1]; H_MAG[1] = -SH_MAG[2]; H_MAG[2] = SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2; H_MAG[3] = SH_MAG[0]; H_MAG[16] = 2.0f*q0*q2 + 2.0f*q1*q3; H_MAG[17] = 2.0f*q2*q3 - 2.0f*q0*q1; H_MAG[18] = SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]; H_MAG[19] = 0.0f; H_MAG[20] = 0.0f; H_MAG[21] = 1.0f; // calculate Kalman gain SK_MZ[0] = 1.0f / varInnovMag[2]; SK_MZ[1] = SH_MAG[3] - SH_MAG[4] - SH_MAG[5] + SH_MAG[6]; SK_MZ[2] = SH_MAG[7] + SH_MAG[8] - 2.0f*magD*q2; SK_MZ[3] = 2.0f*q0*q1 - 2.0f*q2*q3; SK_MZ[4] = 2.0f*q0*q2 + 2.0f*q1*q3; Kfusion[0] = SK_MZ[0]*(P[0][21] + P[0][0]*SH_MAG[1] - P[0][1]*SH_MAG[2] + P[0][3]*SH_MAG[0] + P[0][2]*SK_MZ[2] + P[0][18]*SK_MZ[1] + P[0][16]*SK_MZ[4] - P[0][17]*SK_MZ[3]); Kfusion[1] = SK_MZ[0]*(P[1][21] + P[1][0]*SH_MAG[1] - P[1][1]*SH_MAG[2] + P[1][3]*SH_MAG[0] + P[1][2]*SK_MZ[2] + P[1][18]*SK_MZ[1] + P[1][16]*SK_MZ[4] - P[1][17]*SK_MZ[3]); Kfusion[2] = SK_MZ[0]*(P[2][21] + P[2][0]*SH_MAG[1] - P[2][1]*SH_MAG[2] + P[2][3]*SH_MAG[0] + P[2][2]*SK_MZ[2] + P[2][18]*SK_MZ[1] + P[2][16]*SK_MZ[4] - P[2][17]*SK_MZ[3]); Kfusion[3] = SK_MZ[0]*(P[3][21] + P[3][0]*SH_MAG[1] - P[3][1]*SH_MAG[2] + P[3][3]*SH_MAG[0] + P[3][2]*SK_MZ[2] + P[3][18]*SK_MZ[1] + P[3][16]*SK_MZ[4] - P[3][17]*SK_MZ[3]); Kfusion[4] = SK_MZ[0]*(P[4][21] + P[4][0]*SH_MAG[1] - P[4][1]*SH_MAG[2] + P[4][3]*SH_MAG[0] + P[4][2]*SK_MZ[2] + P[4][18]*SK_MZ[1] + P[4][16]*SK_MZ[4] - P[4][17]*SK_MZ[3]); Kfusion[5] = SK_MZ[0]*(P[5][21] + P[5][0]*SH_MAG[1] - P[5][1]*SH_MAG[2] + P[5][3]*SH_MAG[0] + P[5][2]*SK_MZ[2] + P[5][18]*SK_MZ[1] + P[5][16]*SK_MZ[4] - P[5][17]*SK_MZ[3]); Kfusion[6] = SK_MZ[0]*(P[6][21] + P[6][0]*SH_MAG[1] - P[6][1]*SH_MAG[2] + P[6][3]*SH_MAG[0] + P[6][2]*SK_MZ[2] + P[6][18]*SK_MZ[1] + P[6][16]*SK_MZ[4] - P[6][17]*SK_MZ[3]); Kfusion[7] = SK_MZ[0]*(P[7][21] + P[7][0]*SH_MAG[1] - P[7][1]*SH_MAG[2] + P[7][3]*SH_MAG[0] + P[7][2]*SK_MZ[2] + P[7][18]*SK_MZ[1] + P[7][16]*SK_MZ[4] - P[7][17]*SK_MZ[3]); Kfusion[8] = SK_MZ[0]*(P[8][21] + P[8][0]*SH_MAG[1] - P[8][1]*SH_MAG[2] + P[8][3]*SH_MAG[0] + P[8][2]*SK_MZ[2] + P[8][18]*SK_MZ[1] + P[8][16]*SK_MZ[4] - P[8][17]*SK_MZ[3]); Kfusion[9] = SK_MZ[0]*(P[9][21] + P[9][0]*SH_MAG[1] - P[9][1]*SH_MAG[2] + P[9][3]*SH_MAG[0] + P[9][2]*SK_MZ[2] + P[9][18]*SK_MZ[1] + P[9][16]*SK_MZ[4] - P[9][17]*SK_MZ[3]); if (!inhibitDelAngBiasStates) { Kfusion[10] = SK_MZ[0]*(P[10][21] + P[10][0]*SH_MAG[1] - P[10][1]*SH_MAG[2] + P[10][3]*SH_MAG[0] + P[10][2]*SK_MZ[2] + P[10][18]*SK_MZ[1] + P[10][16]*SK_MZ[4] - P[10][17]*SK_MZ[3]); Kfusion[11] = SK_MZ[0]*(P[11][21] + P[11][0]*SH_MAG[1] - P[11][1]*SH_MAG[2] + P[11][3]*SH_MAG[0] + P[11][2]*SK_MZ[2] + P[11][18]*SK_MZ[1] + P[11][16]*SK_MZ[4] - P[11][17]*SK_MZ[3]); Kfusion[12] = SK_MZ[0]*(P[12][21] + P[12][0]*SH_MAG[1] - P[12][1]*SH_MAG[2] + P[12][3]*SH_MAG[0] + P[12][2]*SK_MZ[2] + P[12][18]*SK_MZ[1] + P[12][16]*SK_MZ[4] - P[12][17]*SK_MZ[3]); } else { // zero indexes 10 to 12 = 3*4 bytes memset(&Kfusion[10], 0, 12); } if (!inhibitDelVelBiasStates) { Kfusion[13] = SK_MZ[0]*(P[13][21] + P[13][0]*SH_MAG[1] - P[13][1]*SH_MAG[2] + P[13][3]*SH_MAG[0] + P[13][2]*SK_MZ[2] + P[13][18]*SK_MZ[1] + P[13][16]*SK_MZ[4] - P[13][17]*SK_MZ[3]); Kfusion[14] = SK_MZ[0]*(P[14][21] + P[14][0]*SH_MAG[1] - P[14][1]*SH_MAG[2] + P[14][3]*SH_MAG[0] + P[14][2]*SK_MZ[2] + P[14][18]*SK_MZ[1] + P[14][16]*SK_MZ[4] - P[14][17]*SK_MZ[3]); Kfusion[15] = SK_MZ[0]*(P[15][21] + P[15][0]*SH_MAG[1] - P[15][1]*SH_MAG[2] + P[15][3]*SH_MAG[0] + P[15][2]*SK_MZ[2] + P[15][18]*SK_MZ[1] + P[15][16]*SK_MZ[4] - P[15][17]*SK_MZ[3]); } else { // zero indexes 13 to 15 = 3*4 bytes memset(&Kfusion[13], 0, 12); } // zero Kalman gains to inhibit magnetic field state estimation if (!inhibitMagStates) { Kfusion[16] = SK_MZ[0]*(P[16][21] + P[16][0]*SH_MAG[1] - P[16][1]*SH_MAG[2] + P[16][3]*SH_MAG[0] + P[16][2]*SK_MZ[2] + P[16][18]*SK_MZ[1] + P[16][16]*SK_MZ[4] - P[16][17]*SK_MZ[3]); Kfusion[17] = SK_MZ[0]*(P[17][21] + P[17][0]*SH_MAG[1] - P[17][1]*SH_MAG[2] + P[17][3]*SH_MAG[0] + P[17][2]*SK_MZ[2] + P[17][18]*SK_MZ[1] + P[17][16]*SK_MZ[4] - P[17][17]*SK_MZ[3]); Kfusion[18] = SK_MZ[0]*(P[18][21] + P[18][0]*SH_MAG[1] - P[18][1]*SH_MAG[2] + P[18][3]*SH_MAG[0] + P[18][2]*SK_MZ[2] + P[18][18]*SK_MZ[1] + P[18][16]*SK_MZ[4] - P[18][17]*SK_MZ[3]); Kfusion[19] = SK_MZ[0]*(P[19][21] + P[19][0]*SH_MAG[1] - P[19][1]*SH_MAG[2] + P[19][3]*SH_MAG[0] + P[19][2]*SK_MZ[2] + P[19][18]*SK_MZ[1] + P[19][16]*SK_MZ[4] - P[19][17]*SK_MZ[3]); Kfusion[20] = SK_MZ[0]*(P[20][21] + P[20][0]*SH_MAG[1] - P[20][1]*SH_MAG[2] + P[20][3]*SH_MAG[0] + P[20][2]*SK_MZ[2] + P[20][18]*SK_MZ[1] + P[20][16]*SK_MZ[4] - P[20][17]*SK_MZ[3]); Kfusion[21] = SK_MZ[0]*(P[21][21] + P[21][0]*SH_MAG[1] - P[21][1]*SH_MAG[2] + P[21][3]*SH_MAG[0] + P[21][2]*SK_MZ[2] + P[21][18]*SK_MZ[1] + P[21][16]*SK_MZ[4] - P[21][17]*SK_MZ[3]); } else { // zero indexes 16 to 21 = 6*4 bytes memset(&Kfusion[16], 0, 24); } // zero Kalman gains to inhibit wind state estimation if (!inhibitWindStates) { Kfusion[22] = SK_MZ[0]*(P[22][21] + P[22][0]*SH_MAG[1] - P[22][1]*SH_MAG[2] + P[22][3]*SH_MAG[0] + P[22][2]*SK_MZ[2] + P[22][18]*SK_MZ[1] + P[22][16]*SK_MZ[4] - P[22][17]*SK_MZ[3]); Kfusion[23] = SK_MZ[0]*(P[23][21] + P[23][0]*SH_MAG[1] - P[23][1]*SH_MAG[2] + P[23][3]*SH_MAG[0] + P[23][2]*SK_MZ[2] + P[23][18]*SK_MZ[1] + P[23][16]*SK_MZ[4] - P[23][17]*SK_MZ[3]); } else { // zero indexes 22 to 23 = 2*4 bytes memset(&Kfusion[22], 0, 8); } // set flags to indicate to other processes that fusion has been performed and is required on the next frame // this can be used by other fusion processes to avoid fusing on the same frame as this expensive step magFusePerformed = true; } // correct the covariance P = (I - K*H)*P // take advantage of the empty columns in KH to reduce the // number of operations for (unsigned i = 0; i<=stateIndexLim; i++) { for (unsigned j = 0; j<=3; j++) { KH[i][j] = Kfusion[i] * H_MAG[j]; } for (unsigned j = 4; j<=15; j++) { KH[i][j] = 0.0f; } for (unsigned j = 16; j<=21; j++) { KH[i][j] = Kfusion[i] * H_MAG[j]; } for (unsigned j = 22; j<=23; j++) { KH[i][j] = 0.0f; } } for (unsigned j = 0; j<=stateIndexLim; j++) { for (unsigned i = 0; i<=stateIndexLim; i++) { ftype res = 0; res += KH[i][0] * P[0][j]; res += KH[i][1] * P[1][j]; res += KH[i][2] * P[2][j]; res += KH[i][3] * P[3][j]; res += KH[i][16] * P[16][j]; res += KH[i][17] * P[17][j]; res += KH[i][18] * P[18][j]; res += KH[i][19] * P[19][j]; res += KH[i][20] * P[20][j]; res += KH[i][21] * P[21][j]; KHP[i][j] = res; } } // Check that we are not going to drive any variances negative and skip the update if so bool healthyFusion = true; for (uint8_t i= 0; i<=stateIndexLim; i++) { if (KHP[i][i] > P[i][i]) { healthyFusion = false; } } if (healthyFusion) { // update the covariance matrix for (uint8_t i= 0; i<=stateIndexLim; i++) { for (uint8_t j= 0; j<=stateIndexLim; j++) { P[i][j] = P[i][j] - KHP[i][j]; } } // force the covariance matrix to be symmetrical and limit the variances to prevent ill-conditioning. ForceSymmetry(); ConstrainVariances(); // correct the state vector for (uint8_t j= 0; j<=stateIndexLim; j++) { statesArray[j] = statesArray[j] - Kfusion[j] * innovMag[obsIndex]; } stateStruct.quat.normalize(); } else { // record bad axis if (obsIndex == 0) { faultStatus.bad_xmag = true; } else if (obsIndex == 1) { faultStatus.bad_ymag = true; } else if (obsIndex == 2) { faultStatus.bad_zmag = true; } CovarianceInit(); return; } } } /* * Fuse magnetic heading measurement using explicit algebraic equations generated with Matlab symbolic toolbox. * The script file used to generate these and other equations in this filter can be found here: * https://github.com/PX4/ecl/blob/master/matlab/scripts/Inertial%20Nav%20EKF/GenerateNavFilterEquations.m * This fusion method only modifies the orientation, does not require use of the magnetic field states and is computationally cheaper. * It is suitable for use when the external magnetic field environment is disturbed (eg close to metal structures, on ground). * It is not as robust to magnetometer failures. * It is not suitable for operation where the horizontal magnetic field strength is weak (within 30 degrees latitude of the magnetic poles) * * The following booleans are passed to the function to control the fusion process: * * usePredictedYaw - Set this to true if no valid yaw measurement will be available for an extended periods. * This uses an innovation set to zero which prevents uncontrolled quaternion covaraince growth. * UseExternalYawSensor - Set this to true if yaw data from an external yaw sensor is being used instead of the magnetometer. */ void NavEKF3_core::fuseEulerYaw(bool usePredictedYaw, bool useExternalYawSensor) { float q0 = stateStruct.quat[0]; float q1 = stateStruct.quat[1]; float q2 = stateStruct.quat[2]; float q3 = stateStruct.quat[3]; // yaw measurement error variance (rad^2) float R_YAW; if (!useExternalYawSensor) { R_YAW = sq(frontend->_yawNoise); } else { R_YAW = sq(yawAngDataDelayed.yawAngErr); } // determine if a 321 or 312 Euler sequence is best bool useEuler321 = true; if (useExternalYawSensor) { // If using an external sensor, the definition of yaw is specified through the sensor interface if (yawAngDataDelayed.type == 2) { useEuler321 = true; } else if (yawAngDataDelayed.type == 1) { useEuler321 = false; } else { // invalid selection return; } } else { // if using the magnetometer, it is determined automatically useEuler321 = (fabsf(prevTnb[0][2]) < fabsf(prevTnb[1][2])); } // calculate observation jacobian, predicted yaw and zero yaw body to earth rotation matrix float yawAngPredicted; float H_YAW[4]; Matrix3f Tbn_zeroYaw; if (useEuler321) { // calculate observation jacobian when we are observing the first rotation in a 321 sequence float t9 = q0*q3; float t10 = q1*q2; float t2 = t9+t10; float t3 = q0*q0; float t4 = q1*q1; float t5 = q2*q2; float t6 = q3*q3; float t7 = t3+t4-t5-t6; float t8 = t7*t7; if (t8 > 1e-6f) { t8 = 1.0f/t8; } else { return; } float t11 = t2*t2; float t12 = t8*t11*4.0f; float t13 = t12+1.0f; float t14; if (fabsf(t13) > 1e-6f) { t14 = 1.0f/t13; } else { return; } H_YAW[0] = t8*t14*(q3*t3-q3*t4+q3*t5+q3*t6+q0*q1*q2*2.0f)*-2.0f; H_YAW[1] = t8*t14*(-q2*t3+q2*t4+q2*t5+q2*t6+q0*q1*q3*2.0f)*-2.0f; H_YAW[2] = t8*t14*(q1*t3+q1*t4+q1*t5-q1*t6+q0*q2*q3*2.0f)*2.0f; H_YAW[3] = t8*t14*(q0*t3+q0*t4-q0*t5+q0*t6+q1*q2*q3*2.0f)*2.0f; // Get the 321 euler angles Vector3f euler321; stateStruct.quat.to_euler(euler321.x, euler321.y, euler321.z); yawAngPredicted = euler321.z; // set the yaw to zero and calculate the zero yaw rotation from body to earth frame Tbn_zeroYaw.from_euler(euler321.x, euler321.y, 0.0f); } else { // calculate observation jacobian when we are observing a rotation in a 312 sequence float t9 = q0*q3; float t10 = q1*q2; float t2 = t9-t10; float t3 = q0*q0; float t4 = q1*q1; float t5 = q2*q2; float t6 = q3*q3; float t7 = t3-t4+t5-t6; float t8 = t7*t7; if (t8 > 1e-6f) { t8 = 1.0f/t8; } else { return; } float t11 = t2*t2; float t12 = t8*t11*4.0f; float t13 = t12+1.0f; float t14; if (fabsf(t13) > 1e-6f) { t14 = 1.0f/t13; } else { return; } H_YAW[0] = t8*t14*(q3*t3+q3*t4-q3*t5+q3*t6-q0*q1*q2*2.0f)*-2.0f; H_YAW[1] = t8*t14*(q2*t3+q2*t4+q2*t5-q2*t6-q0*q1*q3*2.0f)*-2.0f; H_YAW[2] = t8*t14*(-q1*t3+q1*t4+q1*t5+q1*t6-q0*q2*q3*2.0f)*2.0f; H_YAW[3] = t8*t14*(q0*t3-q0*t4+q0*t5+q0*t6-q1*q2*q3*2.0f)*2.0f; // Get the 321 euler angles Vector3f euler312 = stateStruct.quat.to_vector312(); yawAngPredicted = euler312.z; // set the yaw to zero and calculate the zero yaw rotation from body to earth frame Tbn_zeroYaw.from_euler312(euler312.x, euler312.y, 0.0f); } // Calculate the innovation float innovation; if (!usePredictedYaw) { if (!useExternalYawSensor) { // Use the difference between the horizontal projection and declination to give the measured yaw // rotate measured mag components into earth frame Vector3f magMeasNED = Tbn_zeroYaw*magDataDelayed.mag; float yawAngMeasured = wrap_PI(-atan2f(magMeasNED.y, magMeasNED.x) + _ahrs->get_compass()->get_declination()); innovation = wrap_PI(yawAngPredicted - yawAngMeasured); } else { // use the external yaw sensor data innovation = wrap_PI(yawAngPredicted - yawAngDataDelayed.yawAng); } } else { // setting the innovation to zero enables quaternion covariance growth to be constrained when there is no // method of observing yaw innovation = 0.0f; } // Copy raw value to output variable used for data logging innovYaw = innovation; // Calculate innovation variance and Kalman gains, taking advantage of the fact that only the first 4 elements in H are non zero float PH[4]; float varInnov = R_YAW; for (uint8_t rowIndex=0; rowIndex<=3; rowIndex++) { PH[rowIndex] = 0.0f; for (uint8_t colIndex=0; colIndex<=3; colIndex++) { PH[rowIndex] += P[rowIndex][colIndex]*H_YAW[colIndex]; } varInnov += H_YAW[rowIndex]*PH[rowIndex]; } float varInnovInv; if (varInnov >= R_YAW) { varInnovInv = 1.0f / varInnov; // output numerical health status faultStatus.bad_yaw = false; } else { // the calculation is badly conditioned, so we cannot perform fusion on this step // we reset the covariance matrix and try again next measurement CovarianceInit(); // output numerical health status faultStatus.bad_yaw = true; return; } // calculate Kalman gain for (uint8_t rowIndex=0; rowIndex<=stateIndexLim; rowIndex++) { Kfusion[rowIndex] = 0.0f; for (uint8_t colIndex=0; colIndex<=3; colIndex++) { Kfusion[rowIndex] += P[rowIndex][colIndex]*H_YAW[colIndex]; } Kfusion[rowIndex] *= varInnovInv; } // calculate the innovation test ratio yawTestRatio = sq(innovation) / (sq(MAX(0.01f * (float)frontend->_yawInnovGate, 1.0f)) * varInnov); // Declare the magnetometer unhealthy if the innovation test fails if (yawTestRatio > 1.0f) { magHealth = false; // On the ground a large innovation could be due to large initial gyro bias or magnetic interference from nearby objects // If we are flying, then it is more likely due to a magnetometer fault and we should not fuse the data if (inFlight) { return; } } else { magHealth = true; } // limit the innovation so that initial corrections are not too large if (innovation > 0.5f) { innovation = 0.5f; } else if (innovation < -0.5f) { innovation = -0.5f; } // correct the covariance using P = P - K*H*P taking advantage of the fact that only the first 3 elements in H are non zero // calculate K*H*P for (uint8_t row = 0; row <= stateIndexLim; row++) { for (uint8_t column = 0; column <= 3; column++) { KH[row][column] = Kfusion[row] * H_YAW[column]; } } for (uint8_t row = 0; row <= stateIndexLim; row++) { for (uint8_t column = 0; column <= stateIndexLim; column++) { float tmp = KH[row][0] * P[0][column]; tmp += KH[row][1] * P[1][column]; tmp += KH[row][2] * P[2][column]; tmp += KH[row][3] * P[3][column]; KHP[row][column] = tmp; } } // Check that we are not going to drive any variances negative and skip the update if so bool healthyFusion = true; for (uint8_t i= 0; i<=stateIndexLim; i++) { if (KHP[i][i] > P[i][i]) { healthyFusion = false; } } if (healthyFusion) { // update the covariance matrix for (uint8_t i= 0; i<=stateIndexLim; i++) { for (uint8_t j= 0; j<=stateIndexLim; j++) { P[i][j] = P[i][j] - KHP[i][j]; } } // force the covariance matrix to be symmetrical and limit the variances to prevent ill-conditioning. ForceSymmetry(); ConstrainVariances(); // correct the state vector for (uint8_t i=0; i<=stateIndexLim; i++) { statesArray[i] -= Kfusion[i] * innovation; } stateStruct.quat.normalize(); // record fusion numerical health status faultStatus.bad_yaw = false; } else { // record fusion numerical health status faultStatus.bad_yaw = true; } } /* * Fuse declination angle using explicit algebraic equations generated with Matlab symbolic toolbox. * The script file used to generate these and other equations in this filter can be found here: * https://github.com/PX4/ecl/blob/master/matlab/scripts/Inertial%20Nav%20EKF/GenerateNavFilterEquations.m * This is used to prevent the declination of the EKF earth field states from drifting during operation without GPS * or some other absolute position or velocity reference */ void NavEKF3_core::FuseDeclination(float declErr) { // declination error variance (rad^2) const float R_DECL = sq(declErr); // copy required states to local variables float magN = stateStruct.earth_magfield.x; float magE = stateStruct.earth_magfield.y; // prevent bad earth field states from causing numerical errors or exceptions if (magN < 1e-3f) { return; } // Calculate observation Jacobian and Kalman gains // Calculate intermediate variables float t2 = magE*magE; float t3 = magN*magN; float t4 = t2+t3; // if the horizontal magnetic field is too small, this calculation will be badly conditioned if (t4 < 1e-4f) { return; } float t5 = P[16][16]*t2; float t6 = P[17][17]*t3; float t7 = t2*t2; float t8 = R_DECL*t7; float t9 = t3*t3; float t10 = R_DECL*t9; float t11 = R_DECL*t2*t3*2.0f; float t14 = P[16][17]*magE*magN; float t15 = P[17][16]*magE*magN; float t12 = t5+t6+t8+t10+t11-t14-t15; float t13; if (fabsf(t12) > 1e-6f) { t13 = 1.0f / t12; } else { return; } float t18 = magE*magE; float t19 = magN*magN; float t20 = t18+t19; float t21; if (fabsf(t20) > 1e-6f) { t21 = 1.0f/t20; } else { return; } // Calculate the observation Jacobian // Note only 2 terms are non-zero which can be used in matrix operations for calculation of Kalman gains and covariance update to significantly reduce cost float H_DECL[24] = {}; H_DECL[16] = -magE*t21; H_DECL[17] = magN*t21; Kfusion[0] = -t4*t13*(P[0][16]*magE-P[0][17]*magN); Kfusion[1] = -t4*t13*(P[1][16]*magE-P[1][17]*magN); Kfusion[2] = -t4*t13*(P[2][16]*magE-P[2][17]*magN); Kfusion[3] = -t4*t13*(P[3][16]*magE-P[3][17]*magN); Kfusion[4] = -t4*t13*(P[4][16]*magE-P[4][17]*magN); Kfusion[5] = -t4*t13*(P[5][16]*magE-P[5][17]*magN); Kfusion[6] = -t4*t13*(P[6][16]*magE-P[6][17]*magN); Kfusion[7] = -t4*t13*(P[7][16]*magE-P[7][17]*magN); Kfusion[8] = -t4*t13*(P[8][16]*magE-P[8][17]*magN); Kfusion[9] = -t4*t13*(P[9][16]*magE-P[9][17]*magN); if (!inhibitDelAngBiasStates) { Kfusion[10] = -t4*t13*(P[10][16]*magE-P[10][17]*magN); Kfusion[11] = -t4*t13*(P[11][16]*magE-P[11][17]*magN); Kfusion[12] = -t4*t13*(P[12][16]*magE-P[12][17]*magN); } else { // zero indexes 10 to 12 = 3*4 bytes memset(&Kfusion[10], 0, 12); } if (!inhibitDelVelBiasStates) { Kfusion[13] = -t4*t13*(P[13][16]*magE-P[13][17]*magN); Kfusion[14] = -t4*t13*(P[14][16]*magE-P[14][17]*magN); Kfusion[15] = -t4*t13*(P[15][16]*magE-P[15][17]*magN); } else { // zero indexes 13 to 15 = 3*4 bytes memset(&Kfusion[13], 0, 12); } if (!inhibitMagStates) { Kfusion[16] = -t4*t13*(P[16][16]*magE-P[16][17]*magN); Kfusion[17] = -t4*t13*(P[17][16]*magE-P[17][17]*magN); Kfusion[18] = -t4*t13*(P[18][16]*magE-P[18][17]*magN); Kfusion[19] = -t4*t13*(P[19][16]*magE-P[19][17]*magN); Kfusion[20] = -t4*t13*(P[20][16]*magE-P[20][17]*magN); Kfusion[21] = -t4*t13*(P[21][16]*magE-P[21][17]*magN); } else { // zero indexes 16 to 21 = 6*4 bytes memset(&Kfusion[16], 0, 24); } if (!inhibitWindStates) { Kfusion[22] = -t4*t13*(P[22][16]*magE-P[22][17]*magN); Kfusion[23] = -t4*t13*(P[23][16]*magE-P[23][17]*magN); } else { // zero indexes 22 to 23 = 2*4 bytes memset(&Kfusion[22], 0, 8); } // get the magnetic declination float magDecAng = use_compass() ? _ahrs->get_compass()->get_declination() : 0; // Calculate the innovation float innovation = atan2f(magE , magN) - magDecAng; // limit the innovation to protect against data errors if (innovation > 0.5f) { innovation = 0.5f; } else if (innovation < -0.5f) { innovation = -0.5f; } // correct the covariance P = (I - K*H)*P // take advantage of the empty columns in KH to reduce the // number of operations for (unsigned i = 0; i<=stateIndexLim; i++) { for (unsigned j = 0; j<=15; j++) { KH[i][j] = 0.0f; } KH[i][16] = Kfusion[i] * H_DECL[16]; KH[i][17] = Kfusion[i] * H_DECL[17]; for (unsigned j = 18; j<=23; j++) { KH[i][j] = 0.0f; } } for (unsigned j = 0; j<=stateIndexLim; j++) { for (unsigned i = 0; i<=stateIndexLim; i++) { KHP[i][j] = KH[i][16] * P[16][j] + KH[i][17] * P[17][j]; } } // Check that we are not going to drive any variances negative and skip the update if so bool healthyFusion = true; for (uint8_t i= 0; i<=stateIndexLim; i++) { if (KHP[i][i] > P[i][i]) { healthyFusion = false; } } if (healthyFusion) { // update the covariance matrix for (uint8_t i= 0; i<=stateIndexLim; i++) { for (uint8_t j= 0; j<=stateIndexLim; j++) { P[i][j] = P[i][j] - KHP[i][j]; } } // force the covariance matrix to be symmetrical and limit the variances to prevent ill-conditioning. ForceSymmetry(); ConstrainVariances(); // correct the state vector for (uint8_t j= 0; j<=stateIndexLim; j++) { statesArray[j] = statesArray[j] - Kfusion[j] * innovation; } stateStruct.quat.normalize(); // record fusion health status faultStatus.bad_decl = false; } else { // record fusion health status faultStatus.bad_decl = true; } } /******************************************************** * MISC FUNCTIONS * ********************************************************/ // align the NE earth magnetic field states with the published declination void NavEKF3_core::alignMagStateDeclination() { // don't do this if we already have a learned magnetic field if (magFieldLearned) { return; } // get the magnetic declination float magDecAng = use_compass() ? _ahrs->get_compass()->get_declination() : 0; // rotate the NE values so that the declination matches the published value Vector3f initMagNED = stateStruct.earth_magfield; float magLengthNE = norm(initMagNED.x,initMagNED.y); stateStruct.earth_magfield.x = magLengthNE * cosf(magDecAng); stateStruct.earth_magfield.y = magLengthNE * sinf(magDecAng); if (!inhibitMagStates) { // zero the corresponding state covariances if magnetic field state learning is active float var_16 = P[16][16]; float var_17 = P[17][17]; zeroRows(P,16,17); zeroCols(P,16,17); P[16][16] = var_16; P[17][17] = var_17; // fuse the declination angle to establish covariances and prevent large swings in declination // during initial fusion FuseDeclination(0.1f); } } // record a magnetic field state reset event void NavEKF3_core::recordMagReset() { magStateInitComplete = true; if (inFlight) { finalInflightMagInit = true; } // take a snap-shot of the vertical position, quaternion and yaw innovation to use as a reference // for post alignment checks posDownAtLastMagReset = stateStruct.position.z; quatAtLastMagReset = stateStruct.quat; yawInnovAtLastMagReset = innovYaw; }