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ardupilot/libraries/AP_NavEKF/AP_NavEKF.h

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/// -*- 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 <http://www.gnu.org/licenses/>.
*/
#ifndef AP_NavEKF
#define AP_NavEKF
#include <AP_Math/AP_Math.h>
#include <AP_InertialSensor/AP_InertialSensor.h>
#include <AP_Baro/AP_Baro.h>
#include <AP_Airspeed/AP_Airspeed.h>
#include <AP_Compass/AP_Compass.h>
#include <AP_Param/AP_Param.h>
#include "AP_Nav_Common.h"
#include <GCS_MAVLink/GCS_MAVLink.h>
#include <AP_RangeFinder/AP_RangeFinder.h>
// #define MATH_CHECK_INDEXES 1
#include <AP_Math/vectorN.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_PX4 || CONFIG_HAL_BOARD == HAL_BOARD_VRBRAIN
#include <systemlib/perf_counter.h>
#endif
// 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<ftype,2> Vector2;
typedef VectorN<ftype,3> Vector3;
typedef VectorN<ftype,4> Vector4;
typedef VectorN<ftype,5> Vector5;
typedef VectorN<ftype,6> Vector6;
typedef VectorN<ftype,8> Vector8;
typedef VectorN<ftype,9> Vector9;
typedef VectorN<ftype,10> Vector10;
typedef VectorN<ftype,11> Vector11;
typedef VectorN<ftype,13> Vector13;
typedef VectorN<ftype,14> Vector14;
typedef VectorN<ftype,15> Vector15;
typedef VectorN<ftype,22> Vector22;
typedef VectorN<ftype,31> Vector31;
typedef VectorN<ftype,34> Vector34;
typedef VectorN<VectorN<ftype,3>,3> Matrix3;
typedef VectorN<VectorN<ftype,22>,22> Matrix22;
typedef VectorN<VectorN<ftype,34>,22> Matrix34_50;
typedef VectorN<uint32_t,50> 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;
// 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);
// EKF Mavlink Tuneable Parameters
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<state_elements,50> 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
// 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];
#if CONFIG_HAL_BOARD == HAL_BOARD_PX4 || CONFIG_HAL_BOARD == HAL_BOARD_VRBRAIN
// performance counters
perf_counter_t _perf_UpdateFilter;
perf_counter_t _perf_CovariancePrediction;
perf_counter_t _perf_FuseVelPosNED;
perf_counter_t _perf_FuseMagnetometer;
perf_counter_t _perf_FuseAirspeed;
perf_counter_t _perf_FuseSideslip;
perf_counter_t _perf_OpticalFlowEKF;
perf_counter_t _perf_FuseOptFlow;
#endif
// should we assume zero sideslip?
bool assume_zero_sideslip(void) const;
// vehicle specific initial gyro bias uncertainty
float InitialGyroBiasUncertainty(void) const;
};
#if CONFIG_HAL_BOARD != HAL_BOARD_PX4 && CONFIG_HAL_BOARD != HAL_BOARD_VRBRAIN
#define perf_begin(x)
#define perf_end(x)
#endif
#endif // AP_NavEKF
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