/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- /* 22 state EKF based on https://github.com/priseborough/InertialNav Converted from Matlab to C++ by Paul Riseborough This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ #ifndef AP_NavEKF #define AP_NavEKF #include #include #include #include #include #include #include "AP_Nav_Common.h" #include #include // #define MATH_CHECK_INDEXES 1 #include // GPS pre-flight check bit locations #define MASK_GPS_NSATS (1<<0) #define MASK_GPS_HDOP (1<<1) #define MASK_GPS_SPD_ERR (1<<2) #define MASK_GPS_POS_ERR (1<<3) #define MASK_GPS_YAW_ERR (1<<4) #define MASK_GPS_POS_DRIFT (1<<5) #define MASK_GPS_VERT_SPD (1<<6) #define MASK_GPS_HORIZ_SPD (1<<7) class AP_AHRS; class NavEKF { public: typedef float ftype; #if defined(MATH_CHECK_INDEXES) && (MATH_CHECK_INDEXES == 1) typedef VectorN Vector2; typedef VectorN Vector3; typedef VectorN Vector4; typedef VectorN Vector5; typedef VectorN Vector6; typedef VectorN Vector8; typedef VectorN Vector9; typedef VectorN Vector10; typedef VectorN Vector11; typedef VectorN Vector13; typedef VectorN Vector14; typedef VectorN Vector15; typedef VectorN Vector22; typedef VectorN Vector31; typedef VectorN Vector34; typedef VectorN,3> Matrix3; typedef VectorN,22> Matrix22; typedef VectorN,22> Matrix34_50; typedef VectorN Vector_u32_50; #else typedef ftype Vector2[2]; typedef ftype Vector3[3]; typedef ftype Vector4[4]; typedef ftype Vector5[5]; typedef ftype Vector6[6]; typedef ftype Vector8[8]; typedef ftype Vector9[9]; typedef ftype Vector10[10]; typedef ftype Vector11[11]; typedef ftype Vector13[13]; typedef ftype Vector14[14]; typedef ftype Vector15[15]; typedef ftype Vector22[22]; typedef ftype Vector31[31]; typedef ftype Vector34[34]; typedef ftype Matrix3[3][3]; typedef ftype Matrix22[22][22]; typedef ftype Matrix34_50[34][50]; typedef uint32_t Vector_u32_50[50]; #endif // Constructor NavEKF(const AP_AHRS *ahrs, AP_Baro &baro, const RangeFinder &rng); // This function is used to initialise the filter whilst moving, using the AHRS DCM solution // It should NOT be used to re-initialise after a timeout as DCM will also be corrupted bool InitialiseFilterDynamic(void); // Initialise the states from accelerometer and magnetometer data (if present) // This method can only be used when the vehicle is static bool InitialiseFilterBootstrap(void); // Update Filter States - this should be called whenever new IMU data is available void UpdateFilter(void); // Check basic filter health metrics and return a consolidated health status bool healthy(void) const; // Return the last calculated NED position relative to the reference point (m). // If a calculated solution is not available, use the best available data and return false // If false returned, do not use for flight control bool getPosNED(Vector3f &pos) const; // return NED velocity in m/s void getVelNED(Vector3f &vel) const; // Return the rate of change of vertical position in the down diection (dPosD/dt) in m/s // This can be different to the z component of the EKF velocity state because it will fluctuate with height errors and corrections in the EKF // but will always be kinematically consistent with the z component of the EKF position state float getPosDownDerivative(void) const; // This returns the specific forces in the NED frame void getAccelNED(Vector3f &accelNED) const; // return body axis gyro bias estimates in rad/sec void getGyroBias(Vector3f &gyroBias) const; // reset body axis gyro bias estimates void resetGyroBias(void); // Resets the baro so that it reads zero at the current height // Resets the EKF height to zero // Adjusts the EKf origin height so that the EKF height + origin height is the same as before // Returns true if the height datum reset has been performed // If using a range finder for height no reset is performed and it returns false bool resetHeightDatum(void); // Commands the EKF to not use GPS. // This command must be sent prior to arming as it will only be actioned when the filter is in static mode // This command is forgotten by the EKF each time it goes back into static mode (eg the vehicle disarms) // Returns 0 if command rejected // Returns 1 if attitude, vertical velocity and vertical position will be provided // Returns 2 if attitude, 3D-velocity, vertical position and relative horizontal position will be provided uint8_t setInhibitGPS(void); // return the horizontal speed limit in m/s set by optical flow sensor limits // return the scale factor to be applied to navigation velocity gains to compensate for increase in velocity noise with height when using optical flow void getEkfControlLimits(float &ekfGndSpdLimit, float &ekfNavVelGainScaler) const; // return weighting of first IMU in blending function void getIMU1Weighting(float &ret) const; // return the individual Z-accel bias estimates in m/s^2 void getAccelZBias(float &zbias1, float &zbias2) const; // return the NED wind speed estimates in m/s (positive is air moving in the direction of the axis) void getWind(Vector3f &wind) const; // return earth magnetic field estimates in measurement units / 1000 void getMagNED(Vector3f &magNED) const; // return body magnetic field estimates in measurement units / 1000 void getMagXYZ(Vector3f &magXYZ) const; // Return estimated magnetometer offsets // Return true if magnetometer offsets are valid bool getMagOffsets(Vector3f &magOffsets) const; // Return the last calculated latitude, longitude and height in WGS-84 // If a calculated location isn't available, return a raw GPS measurement // The status will return true if a calculation or raw measurement is available // The getFilterStatus() function provides a more detailed description of data health and must be checked if data is to be used for flight control bool getLLH(struct Location &loc) const; // return the latitude and longitude and height used to set the NED origin // All NED positions calculated by the filter are relative to this location // Returns false if the origin has not been set bool getOriginLLH(struct Location &loc) const; // set the latitude and longitude and height used to set the NED origin // All NED positions calcualted by the filter will be relative to this location // The origin cannot be set if the filter is in a flight mode (eg vehicle armed) // Returns false if the filter has rejected the attempt to set the origin bool setOriginLLH(struct Location &loc); // return estimated height above ground level // return false if ground height is not being estimated. bool getHAGL(float &HAGL) const; // return the Euler roll, pitch and yaw angle in radians void getEulerAngles(Vector3f &eulers) const; // return the transformation matrix from XYZ (body) to NED axes void getRotationBodyToNED(Matrix3f &mat) const; // return the quaternions defining the rotation from NED to XYZ (body) axes void getQuaternion(Quaternion &quat) const; // return the innovations for the NED Pos, NED Vel, XYZ Mag and Vtas measurements void getInnovations(Vector3f &velInnov, Vector3f &posInnov, Vector3f &magInnov, float &tasInnov) const; // return the innovation consistency test ratios for the velocity, position, magnetometer and true airspeed measurements void getVariances(float &velVar, float &posVar, float &hgtVar, Vector3f &magVar, float &tasVar, Vector2f &offset) const; // should we use the compass? This is public so it can be used for // reporting via ahrs.use_compass() bool use_compass(void) const; // write the raw optical flow measurements // rawFlowQuality is a measured of quality between 0 and 255, with 255 being the best quality // rawFlowRates are the optical flow rates in rad/sec about the X and Y sensor axes. // rawGyroRates are the sensor rotation rates in rad/sec measured by the sensors internal gyro // The sign convention is that a RH physical rotation of the sensor about an axis produces both a positive flow and gyro rate // msecFlowMeas is the scheduler time in msec when the optical flow data was received from the sensor. void writeOptFlowMeas(uint8_t &rawFlowQuality, Vector2f &rawFlowRates, Vector2f &rawGyroRates, uint32_t &msecFlowMeas); // return data for debugging optical flow fusion void getFlowDebug(float &varFlow, float &gndOffset, float &flowInnovX, float &flowInnovY, float &auxInnov, float &HAGL, float &rngInnov, float &range, float &gndOffsetErr) const; // called by vehicle code to specify that a takeoff is happening // causes the EKF to compensate for expected barometer errors due to ground effect void setTakeoffExpected(bool val); // called by vehicle code to specify that a touchdown is expected to happen // causes the EKF to compensate for expected barometer errors due to ground effect void setTouchdownExpected(bool val); /* return the filter fault status as a bitmasked integer 0 = quaternions are NaN 1 = velocities are NaN 2 = badly conditioned X magnetometer fusion 3 = badly conditioned Y magnetometer fusion 4 = badly conditioned Z magnetometer fusion 5 = badly conditioned airspeed fusion 6 = badly conditioned synthetic sideslip fusion 7 = filter is not initialised */ void getFilterFaults(uint8_t &faults) const; /* return filter timeout status as a bitmasked integer 0 = position measurement timeout 1 = velocity measurement timeout 2 = height measurement timeout 3 = magnetometer measurement timeout 4 = true airspeed measurement timeout 5 = unassigned 6 = unassigned 7 = unassigned */ void getFilterTimeouts(uint8_t &timeouts) const; /* return filter status flags */ void getFilterStatus(nav_filter_status &status) const; /* return filter gps quality check status */ void getFilterGpsStatus(nav_gps_status &status) const; // send an EKF_STATUS_REPORT message to GCS void send_status_report(mavlink_channel_t chan); // provides the height limit to be observed by the control loops // returns false if no height limiting is required // this is needed to ensure the vehicle does not fly too high when using optical flow navigation bool getHeightControlLimit(float &height) const; // returns true of the EKF thinks the GPS is glitching bool getGpsGlitchStatus(void) const; // return the amount of yaw angle change due to the last yaw angle reset in radians // returns the time of the last yaw angle reset or 0 if no reset has ever occurred uint32_t getLastYawResetAngle(float &yawAng); // report any reason for why the backend is refusing to initialise const char *prearm_failure_reason(void) const; static const struct AP_Param::GroupInfo var_info[]; private: const AP_AHRS *_ahrs; AP_Baro &_baro; const RangeFinder &_rng; // the states are available in two forms, either as a Vector34, or // broken down as individual elements. Both are equivalent (same // memory) Vector34 states; struct state_elements { Quaternion quat; // 0..3 Vector3f velocity; // 4..6 Vector3f position; // 7..9 Vector3f gyro_bias; // 10..12 float accel_zbias1; // 13 Vector2f wind_vel; // 14..15 Vector3f earth_magfield; // 16..18 Vector3f body_magfield; // 19..21 float accel_zbias2; // 22 Vector3f vel1; // 23 .. 25 float posD1; // 26 Vector3f vel2; // 27 .. 29 float posD2; // 30 Vector3f omega; // 31 .. 33 } &state; // update the quaternion, velocity and position states using IMU measurements void UpdateStrapdownEquationsNED(); // calculate the predicted state covariance matrix void CovariancePrediction(); // force symmetry on the state covariance matrix void ForceSymmetry(); // copy covariances across from covariance prediction calculation and fix numerical errors void CopyAndFixCovariances(); // constrain variances (diagonal terms) in the state covariance matrix void ConstrainVariances(); // constrain states void ConstrainStates(); // fuse selected position, velocity and height measurements void FuseVelPosNED(); // fuse magnetometer measurements void FuseMagnetometer(); // fuse true airspeed measurements void FuseAirspeed(); // fuse sythetic sideslip measurement of zero void FuseSideslip(); // zero specified range of rows in the state covariance matrix void zeroRows(Matrix22 &covMat, uint8_t first, uint8_t last); // zero specified range of columns in the state covariance matrix void zeroCols(Matrix22 &covMat, uint8_t first, uint8_t last); // store states along with system time stamp in msces void StoreStates(void); // Reset the stored state history and store the current state void StoreStatesReset(void); // recall state vector stored at closest time to the one specified by msec void RecallStates(state_elements &statesForFusion, uint32_t msec); // calculate nav to body quaternions from body to nav rotation matrix void quat2Tbn(Matrix3f &Tbn, const Quaternion &quat) const; // calculate the NED earth spin vector in rad/sec void calcEarthRateNED(Vector3f &omega, int32_t latitude) const; // calculate whether the flight vehicle is on the ground or flying from height, airspeed and GPS speed void SetFlightAndFusionModes(); // initialise the covariance matrix void CovarianceInit(); // helper functions for readIMUData bool readDeltaVelocity(uint8_t ins_index, Vector3f &dVel, float &dVel_dt); bool readDeltaAngle(uint8_t ins_index, Vector3f &dAng); // update IMU delta angle and delta velocity measurements void readIMUData(); // check for new valid GPS data and update stored measurement if available void readGpsData(); // check for new altitude measurement data and update stored measurement if available void readHgtData(); // check for new magnetometer data and update store measurements if available void readMagData(); // check for new airspeed data and update stored measurements if available void readAirSpdData(); // determine when to perform fusion of GPS position and velocity measurements void SelectVelPosFusion(); // determine when to perform fusion of true airspeed measurements void SelectTasFusion(); // determine when to perform fusion of synthetic sideslp measurements void SelectBetaFusion(); // determine when to perform fusion of magnetometer measurements void SelectMagFusion(); // force alignment of the yaw angle using GPS velocity data void alignYawGPS(); // Forced alignment of the wind velocity states so that they are set to the reciprocal of // the ground speed and scaled to 6 m/s. This is used when launching a fly-forward vehicle without an airspeed sensor // on the assumption that launch will be into wind and 6 is representative global average at height // http://maps.google.com/gallery/details?id=zJuaSgXp_WLc.kTBytKPmNODY&hl=en void setWindVelStates(); // initialise the earth magnetic field states using declination and current attitude and magnetometer meaasurements // and return attitude quaternion Quaternion calcQuatAndFieldStates(float roll, float pitch); // zero stored variables void InitialiseVariables(); // reset the horizontal position states uing the last GPS measurement void ResetPosition(void); // reset velocity states using the last GPS measurement void ResetVelocity(void); // reset the vertical position state using the last height measurement void ResetHeight(void); // return true if we should use the airspeed sensor bool useAirspeed(void) const; // return true if the vehicle code has requested the filter to be ready for flight bool getVehicleArmStatus(void) const; // decay GPS horizontal position offset to close to zero at a rate of 1 m/s // this allows large GPS position jumps to be accomodated gradually void decayGpsOffset(void); // Check for filter divergence void checkDivergence(void); // Calculate weighting that is applied to IMU1 accel data to blend data from IMU's 1 and 2 void calcIMU_Weighting(float K1, float K2); // return true if optical flow data is available bool optFlowDataPresent(void) const; // return true if we should use the range finder sensor bool useRngFinder(void) const; // determine when to perform fusion of optical flow measurements void SelectFlowFusion(); // recall omega (angular rate vector) average from time specified by msec to current time // this is useful for motion compensation of optical flow measurements void RecallOmega(Vector3f &omegaAvg, uint32_t msecStart, uint32_t msecEnd); // Estimate terrain offset using a single state EKF void EstimateTerrainOffset(); // fuse optical flow measurements into the main filter void FuseOptFlow(); // Check arm status and perform required checks and mode changes void performArmingChecks(); // Set the NED origin to be used until the next filter reset void setOrigin(); // determine if a takeoff is expected so that we can compensate for expected barometer errors due to ground effect bool getTakeoffExpected(); // determine if a touchdown is expected so that we can compensate for expected barometer errors due to ground effect bool getTouchdownExpected(); // Assess GPS data quality and return true if good enough to align the EKF bool calcGpsGoodToAlign(void); // Read the range finder and take new measurements if available // Apply a median filter to range finder data void readRangeFinder(); // check if the vehicle has taken off during optical flow navigation by looking at inertial and range finder data void detectOptFlowTakeoff(void); // align the NE earth magnetic field states with the published declination void alignMagStateDeclination(); // Check for signs of bad gyro health before flight bool checkGyroHealthPreFlight(void) const; // update inflight calculaton that determines if GPS data is good enough for reliable navigation void calcGpsGoodForFlight(void); // calculate the derivative of the down position using a complementary filter applied to vertical acceleration and EKF height void calcPosDownDerivative(); // EKF Mavlink Tuneable Parameters AP_Int8 _enable; // zero to disable EKF1 AP_Float _gpsHorizVelNoise; // GPS horizontal velocity measurement noise : m/s AP_Float _gpsVertVelNoise; // GPS vertical velocity measurement noise : m/s AP_Float _gpsHorizPosNoise; // GPS horizontal position measurement noise m AP_Float _baroAltNoise; // Baro height measurement noise : m^2 AP_Float _magNoise; // magnetometer measurement noise : gauss AP_Float _easNoise; // equivalent airspeed measurement noise : m/s AP_Float _windVelProcessNoise; // wind velocity state process noise : m/s^2 AP_Float _wndVarHgtRateScale; // scale factor applied to wind process noise due to height rate AP_Float _magEarthProcessNoise; // earth magnetic field process noise : gauss/sec AP_Float _magBodyProcessNoise; // earth magnetic field process noise : gauss/sec AP_Float _gyrNoise; // gyro process noise : rad/s AP_Float _accNoise; // accelerometer process noise : m/s^2 AP_Float _gyroBiasProcessNoise; // gyro bias state process noise : rad/s AP_Float _accelBiasProcessNoise;// accel bias state process noise : m/s^2 AP_Int16 _msecVelDelay; // effective average delay of GPS velocity measurements rel to IMU (msec) AP_Int16 _msecPosDelay; // effective average delay of GPS position measurements rel to (msec) AP_Int8 _fusionModeGPS; // 0 = use 3D velocity, 1 = use 2D velocity, 2 = use no velocity AP_Int8 _gpsVelInnovGate; // Number of standard deviations applied to GPS velocity innovation consistency check AP_Int8 _gpsPosInnovGate; // Number of standard deviations applied to GPS position innovation consistency check AP_Int8 _hgtInnovGate; // Number of standard deviations applied to height innovation consistency check AP_Int8 _magInnovGate; // Number of standard deviations applied to magnetometer innovation consistency check AP_Int8 _tasInnovGate; // Number of standard deviations applied to true airspeed innovation consistency check AP_Int8 _magCal; // Sets activation condition for in-flight magnetometer calibration AP_Int16 _gpsGlitchAccelMax; // Maximum allowed discrepancy between inertial and GPS Horizontal acceleration before GPS data is ignored : cm/s^2 AP_Int8 _gpsGlitchRadiusMax; // Maximum allowed discrepancy between inertial and GPS Horizontal position before GPS glitch is declared : m AP_Int8 _gndGradientSigma; // RMS terrain gradient percentage assumed by the terrain height estimation. AP_Float _flowNoise; // optical flow rate measurement noise AP_Int8 _flowInnovGate; // Number of standard deviations applied to optical flow innovation consistency check AP_Int8 _msecFLowDelay; // effective average delay of optical flow measurements rel to IMU (msec) AP_Int8 _rngInnovGate; // Number of standard deviations applied to range finder innovation consistency check AP_Float _maxFlowRate; // Maximum flow rate magnitude that will be accepted by the filter AP_Int8 _fallback; // EKF-to-DCM fallback strictness. 0 = trust EKF more, 1 = fallback more conservatively. AP_Int8 _altSource; // Primary alt source during optical flow navigation. 0 = use Baro, 1 = use range finder. AP_Int8 _gpsCheck; // Bitmask controlling which preflight GPS checks are bypassed // Tuning parameters const float gpsNEVelVarAccScale; // Scale factor applied to NE velocity measurement variance due to manoeuvre acceleration const float gpsDVelVarAccScale; // Scale factor applied to vertical velocity measurement variance due to manoeuvre acceleration const float gpsPosVarAccScale; // Scale factor applied to horizontal position measurement variance due to manoeuvre acceleration const float msecHgtDelay; // Height measurement delay (msec) const uint16_t msecMagDelay; // Magnetometer measurement delay (msec) const uint16_t msecTasDelay; // Airspeed measurement delay (msec) const uint16_t gpsRetryTimeUseTAS; // GPS retry time with airspeed measurements (msec) const uint16_t gpsRetryTimeNoTAS; // GPS retry time without airspeed measurements (msec) const uint16_t gpsFailTimeWithFlow; // If we have no GPs for longer than this and we have optical flow, then we will switch across to using optical flow (msec) const uint16_t hgtRetryTimeMode0; // Height retry time with vertical velocity measurement (msec) const uint16_t hgtRetryTimeMode12; // Height retry time without vertical velocity measurement (msec) const uint16_t tasRetryTime; // True airspeed timeout and retry interval (msec) const uint32_t magFailTimeLimit_ms; // number of msec before a magnetometer failing innovation consistency checks is declared failed (msec) const float magVarRateScale; // scale factor applied to magnetometer variance due to angular rate const float gyroBiasNoiseScaler; // scale factor applied to gyro bias state process noise when on ground const float accelBiasNoiseScaler; // scale factor applied to accel bias state process noise when on ground const uint16_t msecGpsAvg; // average number of msec between GPS measurements const uint16_t msecHgtAvg; // average number of msec between height measurements const uint16_t msecMagAvg; // average number of msec between magnetometer measurements const uint16_t msecBetaAvg; // average number of msec between synthetic sideslip measurements const uint16_t msecBetaMax; // maximum number of msec between synthetic sideslip measurements const uint16_t msecFlowAvg; // average number of msec between optical flow measurements const float dtVelPos; // number of seconds between position and velocity corrections. This should be a multiple of the imu update interval. const float covTimeStepMax; // maximum time (sec) between covariance prediction updates const float covDelAngMax; // maximum delta angle between covariance prediction updates const uint32_t TASmsecMax; // maximum allowed interval between airspeed measurement updates const float DCM33FlowMin; // If Tbn(3,3) is less than this number, optical flow measurements will not be fused as tilt is too high. const float fScaleFactorPnoise; // Process noise added to focal length scale factor state variance at each time step const uint8_t flowTimeDeltaAvg_ms; // average interval between optical flow measurements (msec) const uint32_t flowIntervalMax_ms; // maximum allowable time between flow fusion events // ground effect tuning parameters const uint16_t gndEffectTimeout_ms; // time in msec that ground effect mode is active after being activated const float gndEffectBaroScaler; // scaler applied to the barometer observation variance when ground effect mode is active // Variables bool statesInitialised; // boolean true when filter states have been initialised bool velHealth; // boolean true if velocity measurements have passed innovation consistency check bool posHealth; // boolean true if position measurements have passed innovation consistency check bool hgtHealth; // boolean true if height measurements have passed innovation consistency check bool magHealth; // boolean true if magnetometer has passed innovation consistency check bool tasHealth; // boolean true if true airspeed has passed innovation consistency check bool velTimeout; // boolean true if velocity measurements have failed innovation consistency check and timed out bool posTimeout; // boolean true if position measurements have failed innovation consistency check and timed out bool hgtTimeout; // boolean true if height measurements have failed innovation consistency check and timed out bool magTimeout; // boolean true if magnetometer measurements have failed for too long and have timed out bool tasTimeout; // boolean true if true airspeed measurements have failed for too long and have timed out bool badMag; // boolean true if the magnetometer is declared to be producing bad data bool badIMUdata; // boolean true if the bad IMU data is detected float gpsNoiseScaler; // Used to scale the GPS measurement noise and consistency gates to compensate for operation with small satellite counts Vector31 Kfusion; // Kalman gain vector Matrix22 KH; // intermediate result used for covariance updates Matrix22 KHP; // intermediate result used for covariance updates Matrix22 P; // covariance matrix VectorN storedStates; // state vectors stored for the last 50 time steps Vector_u32_50 statetimeStamp; // time stamp for each state vector stored Vector3f correctedDelAng; // delta angles about the xyz body axes corrected for errors (rad) Quaternion correctedDelAngQuat; // quaternion representation of correctedDelAng Vector3f correctedDelVel12; // delta velocities along the XYZ body axes for weighted average of IMU1 and IMU2 corrected for errors (m/s) Vector3f correctedDelVel1; // delta velocities along the XYZ body axes for IMU1 corrected for errors (m/s) Vector3f correctedDelVel2; // delta velocities along the XYZ body axes for IMU2 corrected for errors (m/s) Vector3f summedDelAng; // corrected & summed delta angles about the xyz body axes (rad) Vector3f summedDelVel; // corrected & summed delta velocities along the XYZ body axes (m/s) Vector3f lastGyroBias; // previous gyro bias vector used by filter divergence check Matrix3f prevTnb; // previous nav to body transformation used for INS earth rotation compensation ftype accNavMag; // magnitude of navigation accel - used to adjust GPS obs variance (m/s^2) ftype accNavMagHoriz; // magnitude of navigation accel in horizontal plane (m/s^2) Vector3f earthRateNED; // earths angular rate vector in NED (rad/s) Vector3f dVelIMU1; // delta velocity vector in XYZ body axes measured by IMU1 (m/s) Vector3f dVelIMU2; // delta velocity vector in XYZ body axes measured by IMU2 (m/s) Vector3f dAngIMU; // delta angle vector in XYZ body axes measured by the IMU (rad) ftype dtIMUavg; // expected time between IMU measurements (sec) ftype dtIMUactual; // time lapsed since the last IMU measurement (sec) ftype dt; // time lapsed since the last covariance prediction (sec) ftype hgtRate; // state for rate of change of height filter bool onGround; // boolean true when the flight vehicle is on the ground (not flying) bool prevOnGround; // value of onGround from previous update bool manoeuvring; // boolean true when the flight vehicle is performing horizontal changes in velocity uint32_t airborneDetectTime_ms; // last time flight movement was detected Vector6 innovVelPos; // innovation output for a group of measurements Vector6 varInnovVelPos; // innovation variance output for a group of measurements bool fuseVelData; // this boolean causes the velNED measurements to be fused bool fusePosData; // this boolean causes the posNE measurements to be fused bool fuseHgtData; // this boolean causes the hgtMea measurements to be fused Vector3f velNED; // North, East, Down velocity measurements (m/s) Vector2f gpsPosNE; // North, East position measurements (m) ftype hgtMea; // height measurement relative to reference point (m) state_elements statesAtVelTime; // States at the effective time of velNED measurements state_elements statesAtPosTime; // States at the effective time of posNE measurements state_elements statesAtHgtTime; // States at the effective time of hgtMea measurement Vector3f innovMag; // innovation output from fusion of X,Y,Z compass measurements Vector3f varInnovMag; // innovation variance output from fusion of X,Y,Z compass measurements Vector3f magData; // magnetometer flux readings in X,Y,Z body axes state_elements statesAtMagMeasTime; // filter states at the effective time of compass measurements ftype innovVtas; // innovation output from fusion of airspeed measurements ftype varInnovVtas; // innovation variance output from fusion of airspeed measurements bool fuseVtasData; // boolean true when airspeed data is to be fused float VtasMeas; // true airspeed measurement (m/s) state_elements statesAtVtasMeasTime; // filter states at the effective measurement time bool covPredStep; // boolean set to true when a covariance prediction step has been performed bool magFusePerformed; // boolean set to true when magnetometer fusion has been perfomred in that time step bool magFuseRequired; // boolean set to true when magnetometer fusion will be perfomred in the next time step bool posVelFuseStep; // boolean set to true when position and velocity fusion is being performed bool tasFuseStep; // boolean set to true when airspeed fusion is being performed uint32_t TASmsecPrev; // time stamp of last TAS fusion step uint32_t BETAmsecPrev; // time stamp of last synthetic sideslip fusion step uint32_t MAGmsecPrev; // time stamp of last compass fusion step uint32_t HGTmsecPrev; // time stamp of last height measurement fusion step bool constPosMode; // true when fusing a constant position to maintain attitude reference for planned operation without GPS or optical flow data uint32_t lastMagUpdate; // last time compass was updated Vector3f velDotNED; // rate of change of velocity in NED frame Vector3f velDotNEDfilt; // low pass filtered velDotNED uint32_t lastAirspeedUpdate; // last time airspeed was updated uint32_t imuSampleTime_ms; // time that the last IMU value was taken bool newDataGps; // true when new GPS data has arrived bool newDataMag; // true when new magnetometer data has arrived bool newDataTas; // true when new airspeed data has arrived bool tasDataWaiting; // true when new airspeed data is waiting to be fused bool newDataHgt; // true when new height data has arrived uint32_t lastHgtMeasTime; // time of last height measurement used to determine if new data has arrived uint16_t hgtRetryTime; // time allowed without use of height measurements before a height timeout is declared uint32_t lastVelPassTime; // time stamp when GPS velocity measurement last passed innovation consistency check (msec) uint32_t lastPosPassTime; // time stamp when GPS position measurement last passed innovation consistency check (msec) uint32_t lastPosFailTime; // time stamp when GPS position measurement last failed innovation consistency check (msec) uint32_t lastHgtPassTime; // time stamp when height measurement last passed innovation consistency check (msec) uint32_t lastTasPassTime; // time stamp when airspeed measurement last passed innovation consistency check (msec) uint8_t storeIndex; // State vector storage index uint32_t lastStateStoreTime_ms; // time of last state vector storage uint32_t lastFixTime_ms; // time of last GPS fix used to determine if new data has arrived uint32_t timeAtLastAuxEKF_ms; // last time the auxilliary filter was run to fuse range or optical flow measurements uint32_t secondLastFixTime_ms; // time of second last GPS fix used to determine how long since last update uint32_t lastHealthyMagTime_ms; // time the magnetometer was last declared healthy uint32_t ekfStartTime_ms; // time the EKF was started (msec) Vector3f lastAngRate; // angular rate from previous IMU sample used for trapezoidal integrator Vector3f lastAccel1; // acceleration from previous IMU1 sample used for trapezoidal integrator Vector3f lastAccel2; // acceleration from previous IMU2 sample used for trapezoidal integrator Matrix22 nextP; // Predicted covariance matrix before addition of process noise to diagonals Vector22 processNoise; // process noise added to diagonals of predicted covariance matrix Vector15 SF; // intermediate variables used to calculate predicted covariance matrix Vector8 SG; // intermediate variables used to calculate predicted covariance matrix Vector11 SQ; // intermediate variables used to calculate predicted covariance matrix Vector8 SPP; // intermediate variables used to calculate predicted covariance matrix float IMU1_weighting; // Weighting applied to use of IMU1. Varies between 0 and 1. bool yawAligned; // true when the yaw angle has been aligned Vector2f gpsPosGlitchOffsetNE; // offset applied to GPS data in the NE direction to compensate for rapid changes in GPS solution Vector2f lastKnownPositionNE; // last known position uint32_t lastDecayTime_ms; // time of last decay of GPS position offset float velTestRatio; // sum of squares of GPS velocity innovation divided by fail threshold float posTestRatio; // sum of squares of GPS position innovation divided by fail threshold float hgtTestRatio; // sum of squares of baro height innovation divided by fail threshold Vector3f magTestRatio; // sum of squares of magnetometer innovations divided by fail threshold float tasTestRatio; // sum of squares of true airspeed innovation divided by fail threshold bool inhibitWindStates; // true when wind states and covariances are to remain constant bool inhibitMagStates; // true when magnetic field states and covariances are to remain constant bool firstArmComplete; // true when first transition out of static mode has been performed after start up bool firstMagYawInit; // true when the first post takeoff initialisation of earth field and yaw angle has been performed bool secondMagYawInit; // true when the second post takeoff initialisation of earth field and yaw angle has been performed bool flowTimeout; // true when optical flow measurements have time out Vector2f gpsVelGlitchOffset; // Offset applied to the GPS velocity when the gltch radius is being decayed back to zero bool gpsNotAvailable; // bool true when valid GPS data is not available bool vehicleArmed; // true when the vehicle is disarmed bool prevVehicleArmed; // vehicleArmed from previous frame struct Location EKF_origin; // LLH origin of the NED axis system - do not change unless filter is reset bool validOrigin; // true when the EKF origin is valid float gpsSpdAccuracy; // estimated speed accuracy in m/s returned by the UBlox GPS receiver uint32_t lastGpsVelFail_ms; // time of last GPS vertical velocity consistency check fail Vector3f lastMagOffsets; // magnetometer offsets returned by compass object from previous update bool gpsAidingBad; // true when GPS position measurements have been consistently rejected by the filter uint32_t lastGpsAidBadTime_ms; // time in msec gps aiding was last detected to be bad float posDownAtArming; // flight vehicle vertical position at arming used as a reference point bool highYawRate; // true when the vehicle is doing rapid yaw rotation where gyro scel factor errors could cause loss of heading reference float yawRateFilt; // filtered yaw rate used to determine when the vehicle is doing rapid yaw rotation where gyro scel factor errors could cause loss of heading reference bool useGpsVertVel; // true if GPS vertical velocity should be used float yawResetAngle; // Change in yaw angle due to last in-flight yaw reset in radians. A positive value means the yaw angle has increased. uint32_t lastYawReset_ms; // System time at which the last yaw reset occurred. Returned by getLastYawResetAngle uint32_t magYawResetTimer_ms; // timer in msec used to track how long good magnetometer data is failing innovation consistency checks bool consistentMagData; // true when the magnetometers are passing consistency checks bool gpsAccuracyGood; // true when the GPS accuracy is considered to be good enough for safe flight. uint32_t timeAtDisarm_ms; // time of last disarm event in msec float gpsDriftNE; // amount of drift detected in the GPS position during pre-flight GPs checks float gpsVertVelFilt; // amount of filterred vertical GPS velocity detected durng pre-flight GPS checks float gpsHorizVelFilt; // amount of filtered horizontal GPS velocity detected during pre-flight GPS checks bool gpsGoodToAlign; // true when GPS quality is good enough to set an EKF origin and commence GPS navigation uint32_t lastConstPosFuseTime_ms; // last time in msec the constant position constraint was applied float posDownDerivative; // Rate of chage of vertical position (dPosD/dt) in m/s. This is the first time derivative of PosD. float posDown; // Down position state used in calculation of posDownRate Vector3f delAngBiasAtArming; // value of the gyro delta angle bias at arming // Used by smoothing of state corrections Vector10 gpsIncrStateDelta; // vector of corrections to attitude, velocity and position to be applied over the period between the current and next GPS measurement Vector10 hgtIncrStateDelta; // vector of corrections to attitude, velocity and position to be applied over the period between the current and next height measurement Vector10 magIncrStateDelta; // vector of corrections to attitude, velocity and position to be applied over the period between the current and next magnetometer measurement uint8_t gpsUpdateCount; // count of the number of minor state corrections using GPS data uint8_t gpsUpdateCountMax; // limit on the number of minor state corrections using GPS data float gpsUpdateCountMaxInv; // floating point inverse of gpsFilterCountMax uint8_t hgtUpdateCount; // count of the number of minor state corrections using Baro data uint8_t hgtUpdateCountMax; // limit on the number of minor state corrections using Baro data float hgtUpdateCountMaxInv; // floating point inverse of hgtFilterCountMax uint8_t magUpdateCount; // count of the number of minor state corrections using Magnetometer data uint8_t magUpdateCountMax; // limit on the number of minor state corrections using Magnetometer data float magUpdateCountMaxInv; // floating point inverse of magFilterCountMax // variables added for optical flow fusion bool newDataFlow; // true when new optical flow data has arrived bool flowFusePerformed; // true when optical flow fusion has been performed in that time step bool flowDataValid; // true while optical flow data is still fresh state_elements statesAtFlowTime;// States at the middle of the optical flow sample period bool fuseOptFlowData; // this boolean causes the last optical flow measurement to be fused float auxFlowObsInnov; // optical flow rate innovation from 1-state terrain offset estimator float auxFlowObsInnovVar; // innovation variance for optical flow observations from 1-state terrain offset estimator Vector2 flowRadXYcomp; // motion compensated optical flow angular rates(rad/sec) Vector2 flowRadXY; // raw (non motion compensated) optical flow angular rates (rad/sec) uint32_t flowValidMeaTime_ms; // time stamp from latest valid flow measurement (msec) uint32_t rngValidMeaTime_ms; // time stamp from latest valid range measurement (msec) uint32_t flowMeaTime_ms; // time stamp from latest flow measurement (msec) uint8_t flowQuality; // unsigned integer representing quality of optical flow data. 255 is maximum quality. uint32_t gndHgtValidTime_ms; // time stamp from last terrain offset state update (msec) Vector3f omegaAcrossFlowTime; // body angular rates averaged across the optical flow sample period Matrix3f Tnb_flow; // transformation matrix from nav to body axes at the middle of the optical flow sample period Matrix3f Tbn_flow; // transformation matrix from body to nav axes at the middle of the optical flow sample period Vector2 varInnovOptFlow; // optical flow innovations variances (rad/sec)^2 Vector2 innovOptFlow; // optical flow LOS innovations (rad/sec) float Popt; // Optical flow terrain height state covariance (m^2) float terrainState; // terrain position state (m) float prevPosN; // north position at last measurement float prevPosE; // east position at last measurement state_elements statesAtRngTime; // States at the range finder measurement time bool fuseRngData; // true when fusion of range data is demanded float varInnovRng; // range finder observation innovation variance (m^2) float innovRng; // range finder observation innovation (m) float rngMea; // range finder measurement (m) bool inhibitGndState; // true when the terrain position state is to remain constant uint32_t prevFlowFuseTime_ms; // time both flow measurement components passed their innovation consistency checks Vector2 flowTestRatio; // square of optical flow innovations divided by fail threshold used by main filter where >1.0 is a fail float auxFlowTestRatio; // sum of squares of optical flow innovation divided by fail threshold used by 1-state terrain offset estimator float R_LOS; // variance of optical flow rate measurements (rad/sec)^2 float auxRngTestRatio; // square of range finder innovations divided by fail threshold used by main filter where >1.0 is a fail Vector2f flowGyroBias; // bias error of optical flow sensor gyro output uint8_t flowUpdateCount; // count of the number of minor state corrections using optical flow data uint8_t flowUpdateCountMax; // limit on the number of minor state corrections using optical flow data float flowUpdateCountMaxInv; // floating point inverse of flowUpdateCountMax Vector10 flowIncrStateDelta; // vector of corrections to attitude, velocity and position to be applied over the period between the current and next magnetometer measurement bool newDataRng; // true when new valid range finder data has arrived. bool constVelMode; // true when fusing a constant velocity to maintain attitude reference when either optical flow or GPS measurements are lost after arming bool lastConstVelMode; // last value of holdVelocity Vector2f heldVelNE; // velocity held when no aiding is available enum AidingMode {AID_ABSOLUTE=0, // GPS aiding is being used (optical flow may also be used) so position estimates are absolute. AID_NONE=1, // no aiding is being used so only attitude and height estimates are available. Either constVelMode or constPosMode must be used to constrain tilt drift. AID_RELATIVE=2 // only optical flow aiding is being used so position estimates will be relative }; AidingMode PV_AidingMode; // Defines the preferred mode for aiding of velocity and position estimates from the INS bool gndOffsetValid; // true when the ground offset state can still be considered valid bool flowXfailed; // true when the X optical flow measurement has failed the innovation consistency check // Range finder float baroHgtOffset; // offset applied when baro height used as a backup height reference if range-finder fails float rngOnGnd; // Expected range finder reading in metres when vehicle is on ground // Movement detector bool takeOffDetected; // true when takeoff for optical flow navigation has been detected float rangeAtArming; // range finder measurement when armed uint32_t timeAtArming_ms; // time in msec that the vehicle armed // IMU processing float dtDelVel1; float dtDelVel2; // baro ground effect bool expectGndEffectTakeoff; // external state from ArduCopter - takeoff expected uint32_t takeoffExpectedSet_ms; // system time at which expectGndEffectTakeoff was set bool expectGndEffectTouchdown; // external state from ArduCopter - touchdown expected uint32_t touchdownExpectedSet_ms; // system time at which expectGndEffectTouchdown was set float meaHgtAtTakeOff; // height measured at commencement of takeoff // monitoring IMU quality float imuNoiseFiltState1; // peak hold noise estimate for IMU 1 float imuNoiseFiltState2; // peak hold noise estimate for IMU 2 Vector3f accelDiffFilt; // filtered difference between IMU 1 and 2 enum ImuSwitchState { IMUSWITCH_MIXED=0, // IMU 0 & 1 are mixed IMUSWITCH_IMU0, // only IMU 0 is used IMUSWITCH_IMU1 // only IMU 1 is used }; ImuSwitchState lastImuSwitchState; // last switch state (see imuSwitchState enum) // states held by optical flow fusion across time steps // optical flow X,Y motion compensated rate measurements are fused across two time steps // to level computational load as this can be an expensive operation struct { uint8_t obsIndex; Vector4 SH_LOS; Vector10 SK_LOS; ftype q0; ftype q1; ftype q2; ftype q3; ftype vn; ftype ve; ftype vd; ftype pd; Vector2 losPred; } flow_state; struct { bool bad_xmag:1; bool bad_ymag:1; bool bad_zmag:1; bool bad_airspeed:1; bool bad_sideslip:1; } faultStatus; // flags indicating which GPS quality checks are failing struct { bool bad_sAcc:1; bool bad_hAcc:1; bool bad_yaw:1; bool bad_sats:1; bool bad_VZ:1; bool bad_horiz_drift:1; bool bad_hdop:1; bool bad_vert_vel:1; bool bad_fix:1; bool bad_horiz_vel:1; } gpsCheckStatus; // states held by magnetomter fusion across time steps // magnetometer X,Y,Z measurements are fused across three time steps // to level computational load as this is an expensive operation struct { ftype q0; ftype q1; ftype q2; ftype q3; ftype magN; ftype magE; ftype magD; ftype magXbias; ftype magYbias; ftype magZbias; uint8_t obsIndex; Matrix3f DCM; Vector3f MagPred; ftype R_MAG; Vector9 SH_MAG; } mag_state; // string representing last reason for prearm failure char prearm_fail_string[40]; // performance counters AP_HAL::Util::perf_counter_t _perf_UpdateFilter; AP_HAL::Util::perf_counter_t _perf_CovariancePrediction; AP_HAL::Util::perf_counter_t _perf_FuseVelPosNED; AP_HAL::Util::perf_counter_t _perf_FuseMagnetometer; AP_HAL::Util::perf_counter_t _perf_FuseAirspeed; AP_HAL::Util::perf_counter_t _perf_FuseSideslip; AP_HAL::Util::perf_counter_t _perf_OpticalFlowEKF; AP_HAL::Util::perf_counter_t _perf_FuseOptFlow; // should we assume zero sideslip? bool assume_zero_sideslip(void) const; // vehicle specific initial gyro bias uncertainty float InitialGyroBiasUncertainty(void) const; }; #endif // AP_NavEKF