mirror of https://github.com/ArduPilot/ardupilot
305 lines
15 KiB
C++
305 lines
15 KiB
C++
/*
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22 state EKF based on https://github.com/priseborough/InertialNav
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Converted from Matlab to C++ by Paul Riseborough
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <AP_Math/AP_Math.h>
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#include <AP_InertialSensor/AP_InertialSensor.h>
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#include <AP_Baro/AP_Baro.h>
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#include <AP_Airspeed/AP_Airspeed.h>
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#include <AP_Compass/AP_Compass.h>
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#include <AP_Param/AP_Param.h>
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#include "AP_Nav_Common.h"
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#include <GCS_MAVLink/GCS_MAVLink.h>
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#include <AP_RangeFinder/AP_RangeFinder.h>
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#include <AP_Math/vectorN.h>
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// GPS pre-flight check bit locations
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#define MASK_GPS_NSATS (1<<0)
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#define MASK_GPS_HDOP (1<<1)
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#define MASK_GPS_SPD_ERR (1<<2)
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#define MASK_GPS_POS_ERR (1<<3)
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#define MASK_GPS_YAW_ERR (1<<4)
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#define MASK_GPS_POS_DRIFT (1<<5)
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#define MASK_GPS_VERT_SPD (1<<6)
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#define MASK_GPS_HORIZ_SPD (1<<7)
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class AP_AHRS;
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class NavEKF_core;
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class NavEKF
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{
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friend class NavEKF_core;
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public:
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// Constructor
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NavEKF(const AP_AHRS *ahrs, AP_Baro &baro, const RangeFinder &rng);
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// allow logging to determine if the EKF is enabled
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bool enabled(void) const {
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return (_enable != 0);
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}
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// This function is used to initialise the filter whilst moving, using the AHRS DCM solution
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// It should NOT be used to re-initialise after a timeout as DCM will also be corrupted
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bool InitialiseFilterDynamic(void);
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// Initialise the states from accelerometer and magnetometer data (if present)
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// This method can only be used when the vehicle is static
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bool InitialiseFilterBootstrap(void);
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// Update Filter States - this should be called whenever new IMU data is available
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void UpdateFilter(void);
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// Check basic filter health metrics and return a consolidated health status
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bool healthy(void) const;
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// Write the last calculated North East position relative to the reference point (m).
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// If a calculated solution is not available, use the best available data and return false
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// If false returned, do not use for flight control
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bool getPosNE(Vector2f &posNE) const;
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// Write the last calculated Down position relative to the reference point (m).
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// If a calculated solution is not available, use the best available data and return false
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// If false returned, do not use for flight control
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bool getPosD(float &posD) const;
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// return NED velocity in m/s
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void getVelNED(Vector3f &vel) const;
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// Return the rate of change of vertical position in the down diection (dPosD/dt) in m/s
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// 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
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// but will always be kinematically consistent with the z component of the EKF position state
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float getPosDownDerivative(void) const;
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// This returns the specific forces in the NED frame
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void getAccelNED(Vector3f &accelNED) const;
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// return body axis gyro bias estimates in rad/sec
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void getGyroBias(Vector3f &gyroBias) const;
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// reset body axis gyro bias estimates
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void resetGyroBias(void);
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// Resets the baro so that it reads zero at the current height
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// Resets the EKF height to zero
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// Adjusts the EKf origin height so that the EKF height + origin height is the same as before
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// Returns true if the height datum reset has been performed
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// If using a range finder for height no reset is performed and it returns false
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bool resetHeightDatum(void);
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// Commands the EKF to not use GPS.
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// This command must be sent prior to arming as it will only be actioned when the filter is in static mode
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// This command is forgotten by the EKF each time it goes back into static mode (eg the vehicle disarms)
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// Returns 0 if command rejected
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// Returns 1 if attitude, vertical velocity and vertical position will be provided
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// Returns 2 if attitude, 3D-velocity, vertical position and relative horizontal position will be provided
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uint8_t setInhibitGPS(void);
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// return the horizontal speed limit in m/s set by optical flow sensor limits
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// return the scale factor to be applied to navigation velocity gains to compensate for increase in velocity noise with height when using optical flow
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void getEkfControlLimits(float &ekfGndSpdLimit, float &ekfNavVelGainScaler) const;
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// return weighting of first IMU in blending function
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void getIMU1Weighting(float &ret) const;
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// return the individual Z-accel bias estimates in m/s^2
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void getAccelZBias(float &zbias1, float &zbias2) const;
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// return the NED wind speed estimates in m/s (positive is air moving in the direction of the axis)
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void getWind(Vector3f &wind) const;
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// return earth magnetic field estimates in measurement units / 1000
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void getMagNED(Vector3f &magNED) const;
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// return body magnetic field estimates in measurement units / 1000
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void getMagXYZ(Vector3f &magXYZ) const;
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// Return estimated magnetometer offsets
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// Return true if magnetometer offsets are valid
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bool getMagOffsets(uint8_t mag_idx, Vector3f &magOffsets) const;
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// Return the last calculated latitude, longitude and height in WGS-84
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// If a calculated location isn't available, return a raw GPS measurement
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// The status will return true if a calculation or raw measurement is available
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// The getFilterStatus() function provides a more detailed description of data health and must be checked if data is to be used for flight control
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bool getLLH(struct Location &loc) const;
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// return the latitude and longitude and height used to set the NED origin
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// All NED positions calculated by the filter are relative to this location
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// Returns false if the origin has not been set
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bool getOriginLLH(struct Location &loc) const;
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// set the latitude and longitude and height used to set the NED origin
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// All NED positions calcualted by the filter will be relative to this location
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// The origin cannot be set if the filter is in a flight mode (eg vehicle armed)
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// Returns false if the filter has rejected the attempt to set the origin
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bool setOriginLLH(struct Location &loc);
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// return estimated height above ground level
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// return false if ground height is not being estimated.
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bool getHAGL(float &HAGL) const;
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// return the Euler roll, pitch and yaw angle in radians
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void getEulerAngles(Vector3f &eulers) const;
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// return the transformation matrix from XYZ (body) to NED axes
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void getRotationBodyToNED(Matrix3f &mat) const;
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// return the quaternions defining the rotation from NED to XYZ (body) axes
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void getQuaternion(Quaternion &quat) const;
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// return the innovations for the NED Pos, NED Vel, XYZ Mag and Vtas measurements
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void getInnovations(Vector3f &velInnov, Vector3f &posInnov, Vector3f &magInnov, float &tasInnov) const;
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// return the innovation consistency test ratios for the velocity, position, magnetometer and true airspeed measurements
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void getVariances(float &velVar, float &posVar, float &hgtVar, Vector3f &magVar, float &tasVar, Vector2f &offset) const;
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// should we use the compass? This is public so it can be used for
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// reporting via ahrs.use_compass()
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bool use_compass(void) const;
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// write the raw optical flow measurements
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// rawFlowQuality is a measured of quality between 0 and 255, with 255 being the best quality
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// rawFlowRates are the optical flow rates in rad/sec about the X and Y sensor axes.
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// rawGyroRates are the sensor rotation rates in rad/sec measured by the sensors internal gyro
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// The sign convention is that a RH physical rotation of the sensor about an axis produces both a positive flow and gyro rate
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// msecFlowMeas is the scheduler time in msec when the optical flow data was received from the sensor.
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void writeOptFlowMeas(uint8_t &rawFlowQuality, Vector2f &rawFlowRates, Vector2f &rawGyroRates, uint32_t &msecFlowMeas);
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// return data for debugging optical flow fusion
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void getFlowDebug(float &varFlow, float &gndOffset, float &flowInnovX, float &flowInnovY, float &auxInnov, float &HAGL, float &rngInnov, float &range, float &gndOffsetErr) const;
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// called by vehicle code to specify that a takeoff is happening
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// causes the EKF to compensate for expected barometer errors due to ground effect
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void setTakeoffExpected(bool val);
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// called by vehicle code to specify that a touchdown is expected to happen
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// causes the EKF to compensate for expected barometer errors due to ground effect
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void setTouchdownExpected(bool val);
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/*
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return the filter fault status as a bitmasked integer
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0 = quaternions are NaN
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1 = velocities are NaN
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2 = badly conditioned X magnetometer fusion
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3 = badly conditioned Y magnetometer fusion
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4 = badly conditioned Z magnetometer fusion
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5 = badly conditioned airspeed fusion
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6 = badly conditioned synthetic sideslip fusion
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7 = filter is not initialised
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*/
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void getFilterFaults(uint16_t &faults) const;
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/*
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return filter timeout status as a bitmasked integer
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0 = position measurement timeout
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1 = velocity measurement timeout
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2 = height measurement timeout
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3 = magnetometer measurement timeout
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4 = true airspeed measurement timeout
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5 = unassigned
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6 = unassigned
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7 = unassigned
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*/
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void getFilterTimeouts(uint8_t &timeouts) const;
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/*
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return filter status flags
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*/
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void getFilterStatus(nav_filter_status &status) const;
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/*
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return filter gps quality check status
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*/
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void getFilterGpsStatus(nav_gps_status &status) const;
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// send an EKF_STATUS_REPORT message to GCS
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void send_status_report(mavlink_channel_t chan);
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// provides the height limit to be observed by the control loops
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// returns false if no height limiting is required
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// this is needed to ensure the vehicle does not fly too high when using optical flow navigation
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bool getHeightControlLimit(float &height) const;
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// returns true of the EKF thinks the GPS is glitching
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bool getGpsGlitchStatus(void) const;
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// return the amount of yaw angle change due to the last yaw angle reset in radians
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// returns the time of the last yaw angle reset or 0 if no reset has ever occurred
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uint32_t getLastYawResetAngle(float &yawAng) const;
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// return the amount of NE position change due to the last position reset in metres
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// returns the time of the last reset or 0 if no reset has ever occurred
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uint32_t getLastPosNorthEastReset(Vector2f &pos) const;
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// return the amount of NE velocity change due to the last velocity reset in metres/sec
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// returns the time of the last reset or 0 if no reset has ever occurred
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uint32_t getLastVelNorthEastReset(Vector2f &vel) const;
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// report any reason for why the backend is refusing to initialise
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const char *prearm_failure_reason(void) const;
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static const struct AP_Param::GroupInfo var_info[];
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private:
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const AP_AHRS *_ahrs;
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AP_Baro &_baro;
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const RangeFinder &_rng;
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NavEKF_core *core;
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// EKF Mavlink Tuneable Parameters
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AP_Int8 _enable; // zero to disable EKF1
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AP_Float _gpsHorizVelNoise; // GPS horizontal velocity measurement noise : m/s
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AP_Float _gpsVertVelNoise; // GPS vertical velocity measurement noise : m/s
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AP_Float _gpsHorizPosNoise; // GPS horizontal position measurement noise m
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AP_Float _baroAltNoise; // Baro height measurement noise : m^2
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AP_Float _magNoise; // magnetometer measurement noise : gauss
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AP_Float _easNoise; // equivalent airspeed measurement noise : m/s
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AP_Float _windVelProcessNoise; // wind velocity state process noise : m/s^2
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AP_Float _wndVarHgtRateScale; // scale factor applied to wind process noise due to height rate
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AP_Float _magEarthProcessNoise; // earth magnetic field process noise : gauss/sec
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AP_Float _magBodyProcessNoise; // earth magnetic field process noise : gauss/sec
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AP_Float _gyrNoise; // gyro process noise : rad/s
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AP_Float _accNoise; // accelerometer process noise : m/s^2
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AP_Float _gyroBiasProcessNoise; // gyro bias state process noise : rad/s
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AP_Float _accelBiasProcessNoise;// accel bias state process noise : m/s^2
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AP_Int16 _msecVelDelay; // effective average delay of GPS velocity measurements rel to IMU (msec)
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AP_Int16 _msecPosDelay; // effective average delay of GPS position measurements rel to (msec)
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AP_Int8 _fusionModeGPS; // 0 = use 3D velocity, 1 = use 2D velocity, 2 = use no velocity
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AP_Int8 _gpsVelInnovGate; // Number of standard deviations applied to GPS velocity innovation consistency check
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AP_Int8 _gpsPosInnovGate; // Number of standard deviations applied to GPS position innovation consistency check
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AP_Int8 _hgtInnovGate; // Number of standard deviations applied to height innovation consistency check
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AP_Int8 _magInnovGate; // Number of standard deviations applied to magnetometer innovation consistency check
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AP_Int8 _tasInnovGate; // Number of standard deviations applied to true airspeed innovation consistency check
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AP_Int8 _magCal; // Sets activation condition for in-flight magnetometer calibration
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AP_Int16 _gpsGlitchAccelMax; // Maximum allowed discrepancy between inertial and GPS Horizontal acceleration before GPS data is ignored : cm/s^2
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AP_Int8 _gpsGlitchRadiusMax; // Maximum allowed discrepancy between inertial and GPS Horizontal position before GPS glitch is declared : m
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AP_Int8 _gndGradientSigma; // RMS terrain gradient percentage assumed by the terrain height estimation.
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AP_Float _flowNoise; // optical flow rate measurement noise
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AP_Int8 _flowInnovGate; // Number of standard deviations applied to optical flow innovation consistency check
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AP_Int8 _msecFLowDelay; // effective average delay of optical flow measurements rel to IMU (msec)
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AP_Int8 _rngInnovGate; // Number of standard deviations applied to range finder innovation consistency check
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AP_Float _maxFlowRate; // Maximum flow rate magnitude that will be accepted by the filter
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AP_Int8 _fallback; // EKF-to-DCM fallback strictness. 0 = trust EKF more, 1 = fallback more conservatively.
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AP_Int8 _altSource; // Primary alt source during optical flow navigation. 0 = use Baro, 1 = use range finder.
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AP_Int8 _gpsCheck; // Bitmask controlling which preflight GPS checks are bypassed
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};
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