EK3_ parameters

67 parameters in the EK3_ family. ArduCopter 4.7 only — other vehicles share many of these names but not always the same ranges or meanings.

EK3_ABIAS_P_NSE

Accelerometer bias stability (m/s^3)

This noise controls the growth of the vertical accelerometer delta velocity bias state error estimate. Increasing it makes accelerometer bias estimation faster and noisier.

Units	m/s/s/s
Range	0.00001 to 0.02
User level	Advanced

EK3_ACC_BIAS_LIM

Accelerometer bias limit

The accelerometer bias state will be limited to +- this value

Units	m/s/s
Range	0.5 to 2.5
Increment	0.1
User level	Advanced

EK3_ACC_P_NSE

Accelerometer noise (m/s^2)

This control disturbance noise controls the growth of estimated error due to accelerometer measurement errors excluding bias. Increasing it makes the flter trust the accelerometer measurements less and other measurements more.

Units	m/s/s
Range	0.01 to 1.0
Increment	0.01
User level	Advanced

EK3_AFFINITY

EKF3 Sensor Affinity Options

These options control the affinity between sensor instances and EKF cores

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Bitmask

Value	Meaning
0	EnableGPSAffinity
1	EnableBaroAffinity
2	EnableCompassAffinity
3	EnableAirspeedAffinity

EK3_ALT_M_NSE

Altitude measurement noise (m)

This is the RMS value of noise in the altitude measurement. Increasing it reduces the weighting of the baro measurement and will make the filter respond more slowly to baro measurement errors, but will make it more sensitive to GPS and accelerometer errors. A larger value for EK3_ALT_M_NSE may be required when operating with EK3_SRCx_POSZ = 0. This parameter also sets the noise for the ‘synthetic’ zero height measurement that is used when EK3_SRCx_POSZ = 0.

Units	m
Range	0.1 to 100.0
Increment	0.1
User level	Advanced

EK3_BCN_DELAY

Range beacon measurement delay (msec)

This is the number of msec that the range beacon measurements lag behind the inertial measurements.

Units	ms
Range	0 to 250
Increment	10
Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

EK3_BCN_I_GTE

Range beacon measurement gate size

This sets the percentage number of standard deviations applied to the range beacon measurement innovation consistency check. Decreasing it makes it more likely that good measurements will be rejected. Increasing it makes it more likely that bad measurements will be accepted.

Range	100 to 1000
Increment	25
User level	Advanced

EK3_BCN_M_NSE

Range beacon measurement noise (m)

This is the RMS value of noise in the range beacon measurement. Increasing it reduces the weighting on this measurement.

Units	m
Range	0.1 to 10.0
Increment	0.1
User level	Advanced

EK3_BETA_MASK

Bitmask controlling sidelip angle fusion

1 byte bitmap controlling use of sideslip angle fusion for estimation of non wind states during operation of ‘fly forward’ vehicle types such as fixed wing planes. By assuming that the angle of sideslip is small, the wind velocity state estimates are corrected whenever the EKF is not dead reckoning (e.g. has an independent velocity or position sensor such as GPS). This behaviour is on by default and cannot be disabled. When the EKF is dead reckoning, the wind states are used as a reference, enabling use of the small angle of sideslip assumption to correct non wind velocity states (eg attitude, velocity, position, etc) and improve navigation accuracy. This behaviour is on by default and cannot be disabled. The behaviour controlled by this parameter is the use of the small angle of sideslip assumption to correct non wind velocity states when the EKF is NOT dead reckoning. This is primarily of benefit to reduce the buildup of yaw angle errors during straight and level flight without a yaw sensor (e.g. magnetometer or dual antenna GPS yaw) provided aerobatic flight maneuvers with large sideslip angles are not performed. The ‘always’ option might be used where the yaw sensor is intentionally not fitted or disabled. The ‘WhenNoYawSensor’ option might be used if a yaw sensor is fitted, but protection against in-flight failure and continual rejection by the EKF is desired. For vehicles operated within visual range of the operator performing frequent turning maneuvers, setting this parameter is unnecessary.

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Bitmask

Value	Meaning
0	Always
1	WhenNoYawSensor

EK3_CHECK_SCALE

GPS accuracy check scaler (%)

This scales the thresholds that are used to check GPS accuracy before it is used by the EKF. A value of 100 is the default. Values greater than 100 increase and values less than 100 reduce the maximum GPS error the EKF will accept. A value of 200 will double the allowable GPS error.

Units	%
Range	50 to 200
User level	Advanced

EK3_DRAG_BCOEF_X

Ballistic coefficient for X axis drag

Ratio of mass to drag coefficient measured along the X body axis. This parameter enables estimation of wind drift for vehicles with bluff bodies and without propulsion forces in the X and Y direction (eg multicopters). The drag produced by this effect scales with speed squared. Set to a positive value > 1.0 to enable. A starting value is the mass in Kg divided by the frontal area. The predicted drag from the rotors is specified separately by the EK3_DRAG_MCOEF parameter.

Units	kg/m/m
Range	0.0 to 1000.0
User level	Advanced

EK3_DRAG_BCOEF_Y

Ballistic coefficient for Y axis drag

Ratio of mass to drag coefficient measured along the Y body axis. This parameter enables estimation of wind drift for vehicles with bluff bodies and without propulsion forces in the X and Y direction (eg multicopters). The drag produced by this effect scales with speed squared. Set to a positive value > 1.0 to enable. A starting value is the mass in Kg divided by the side area. The predicted drag from the rotors is specified separately by the EK3_DRAG_MCOEF parameter.

Units	kg/m/m
Range	50.0 to 1000.0
User level	Advanced

EK3_DRAG_MCOEF

Momentum coefficient for propeller drag

This parameter is used to predict the drag produced by the rotors when flying a multi-copter, enabling estimation of wind drift. The drag produced by this effect scales with speed not speed squared and is produced because some of the air velocity normal to the rotors axis of rotation is lost when passing through the rotor disc which changes the momentum of the airflow causing drag. For unducted rotors the effect is roughly proportional to the area of the propeller blades when viewed side on and changes with different propellers. It is higher for ducted rotors. For example if flying at 15 m/s at sea level conditions produces a rotor induced drag acceleration of 1.5 m/s/s, then EK3_DRAG_MCOEF would be set to 0.1 = (1.5/15.0). Set EK3_MCOEF to a positive value to enable wind estimation using this drag effect. To account for the drag produced by the body which scales with speed squared, see documentation for the EK3_DRAG_BCOEF_X and EK3_DRAG_BCOEF_Y parameters.

Units	1/s
Range	0.0 to 1.0
Increment	0.01
User level	Advanced

EK3_DRAG_M_NSE

Observation noise for drag acceleration

This sets the amount of noise used when fusing X and Y acceleration as an observation that enables estimation of wind velocity for multi-rotor vehicles. This feature is enabled by the EK3_DRAG_BCOEF_X and EK3_DRAG_BCOEF_Y parameters

Units	m/s/s
Range	0.1 to 2.0
Increment	0.1
User level	Advanced

EK3_EAS_I_GATE

Airspeed measurement gate size

This sets the percentage number of standard deviations applied to the airspeed measurement innovation consistency check. Decreasing it makes it more likely that good measurements will be rejected. Increasing it makes it more likely that bad measurements will be accepted.

Range	100 to 1000
Increment	25
User level	Advanced

EK3_EAS_M_NSE

Equivalent airspeed measurement noise (m/s)

This is the RMS value of noise in equivalent airspeed measurements used by planes. Increasing it reduces the weighting of airspeed measurements and will make wind speed estimates less noisy and slower to converge. Increasing also increases navigation errors when dead-reckoning without GPS measurements.

Units	m/s
Range	0.5 to 5.0
Increment	0.1
User level	Advanced

EK3_ENABLE

Enable EKF3

This enables EKF3. Enabling EKF3 only makes the maths run, it does not mean it will be used for flight control. To use it for flight control set AHRS_EKF_TYPE=3. A reboot or restart will need to be performed after changing the value of EK3_ENABLE for it to take effect.

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Values

Value	Meaning
0	Disabled
1	Enabled

EK3_ERR_THRESH

EKF3 Lane Relative Error Sensitivity Threshold

lanes have to be consistently better than the primary by at least this threshold to reduce their overall relativeCoreError, lowering this makes lane switching more sensitive to smaller error differences

Range	0.05 to 1
Increment	0.05
User level	Advanced

EK3_FLOW_DELAY

Optical Flow measurement delay (msec)

This is the number of msec that the optical flow measurements lag behind the inertial measurements. It is the time from the end of the optical flow averaging period and does not include the time delay due to the 100msec of averaging within the flow sensor.

Units	ms
Range	0 to 250
Increment	10
Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

EK3_FLOW_I_GATE

Optical Flow measurement gate size

This sets the percentage number of standard deviations applied to the optical flow innovation consistency check. Decreasing it makes it more likely that good measurements will be rejected. Increasing it makes it more likely that bad measurements will be accepted.

Range	100 to 1000
Increment	25
User level	Advanced

EK3_FLOW_MAX

Optical flow rate maximum

The maximum optical flow rate in rad/sec that will be accepted by the filter. Flow rates above this value will not be fused.

Units	rad/s
Range	1.0 to 4.0
Increment	0.1
User level	Advanced

EK3_FLOW_M_NSE

Optical flow measurement noise (rad/s)

This is the RMS value of noise and errors in optical flow measurements. Increasing it reduces the weighting on these measurements.

Units	rad/s
Range	0.05 to 1.0
Increment	0.05
User level	Advanced

EK3_FLOW_USE

Optical flow use bitmask

Controls if the optical flow data is fused into the 24-state navigation estimator OR the 1-state terrain height estimator.

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Values

Value	Meaning
0	None
1	Navigation
2	Terrain

EK3_GBIAS_P_NSE

Rate gyro bias stability (rad/s/s)

This state process noise controls growth of the gyro delta angle bias state error estimate. Increasing it makes rate gyro bias estimation faster and noisier.

Units	rad/s/s
Range	0.00001 to 0.001
User level	Advanced

EK3_GLITCH_RAD

GPS glitch radius gate size (m)

This controls the maximum radial uncertainty in position between the value predicted by the filter and the value measured by the GPS before the filter position and velocity states are reset to the GPS. Making this value larger allows the filter to ignore larger GPS glitches but also means that non-GPS errors such as IMU and compass can create a larger error in position before the filter is forced back to the GPS position. If EK3_GLITCH_RAD set to 0 the GPS innovations will be clipped instead of rejected if they exceed the gate size set by EK3_VEL_I_GATE and EK3_POS_I_GATE which can be useful if poor quality sensor data is causing GPS rejection and loss of navigation but does make the EKF more susceptible to GPS glitches. If setting EK3_GLITCH_RAD to 0 it is recommended to reduce EK3_VEL_I_GATE and EK3_POS_I_GATE to 300.

Units	m
Range	10 to 100
Increment	5
User level	Advanced

EK3_GND_EFF_DZ

Baro height ground effect dead zone

This parameter sets the size of the dead zone that is applied to negative baro height spikes that can occur when taking off or landing when a vehicle with lift rotors is operating in ground effect ground effect. Set to about 0.5m less than the amount of negative offset in baro height that occurs just prior to takeoff when lift motors are spooling up. Set to 0 if no ground effect is present.

Range	0.0 to 10.0
Increment	0.5
User level	Advanced

EK3_GPS_CHECK

GPS preflight check

This is a 1 byte bitmap controlling which GPS preflight checks are performed. Set to 0 to bypass all checks. Set to 255 perform all checks. Set to 3 to check just the number of satellites and HDoP. Set to 31 for the most rigorous checks that will still allow checks to pass when the copter is moving, eg launch from a boat.

User level

Advanced

Bitmask

Value	Meaning
0	NSats
1	HDoP
2	speed error
3	position error
4	yaw error
5	pos drift
6	vert speed
7	horiz speed

EK3_GPS_VACC_MAX

GPS vertical accuracy threshold

Vertical accuracy threshold for GPS as the altitude source. The GPS will not be used as an altitude source if the reported vertical accuracy of the GPS is larger than this threshold, falling back to baro instead. Set to zero to deactivate the threshold check.

Units	m
Range	0.0 to 10.0
Increment	0.1
User level	Advanced

EK3_GSF_RST_MAX

Maximum number of resets to the EKF-GSF yaw estimate allowed

Sets the maximum number of times the EKF3 will be allowed to reset its yaw to the estimate from the EKF-GSF yaw estimator. No resets will be allowed unless the use of the EKF-GSF yaw estimate is enabled via the EK3_GSF_USE_MASK parameter.

Range	1 to 10
Increment	1
Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

EK3_GSF_RUN_MASK

Bitmask of which EKF-GSF yaw estimators run

1 byte bitmap of which EKF3 instances run an independent EKF-GSF yaw estimator to provide a backup yaw estimate that doesn’t rely on magnetometer data. This estimator uses IMU, GPS and, if available, airspeed data. EKF-GSF yaw estimator data for the primary EKF3 instance will be logged as GSF0 and GSF1 messages. Use of the yaw estimate generated by this algorithm is controlled by the EK3_GSF_USE_MASK and EK3_GSF_RST_MAX parameters. To run the EKF-GSF yaw estimator in ride-along and logging only, set EK3_GSF_USE to 0.

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Bitmask

Value	Meaning
0	FirstEKF
1	SecondEKF
2	ThirdEKF
3	FourthEKF
4	FifthEKF
5	SixthEKF

EK3_GSF_USE_MASK

Bitmask of which EKF-GSF yaw estimators are used

A bitmask of which EKF3 instances will use the output from the EKF-GSF yaw estimator that has been turned on by the EK3_GSF_RUN_MASK parameter. If the inertial navigation calculation stops following the GPS, then the vehicle code can request EKF3 to attempt to resolve the issue, either by performing a yaw reset if enabled by this parameter by switching to another EKF3 instance.

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Bitmask

Value	Meaning
0	FirstEKF
1	SecondEKF
2	ThirdEKF
3	FourthEKF
4	FifthEKF
5	SixthEKF

EK3_GYRO_P_NSE

Rate gyro noise (rad/s)

This control disturbance noise controls the growth of estimated error due to gyro measurement errors excluding bias. Increasing it makes the flter trust the gyro measurements less and other measurements more.

Units	rad/s
Range	0.0001 to 0.1
Increment	0.0001
User level	Advanced

EK3_HGT_DELAY

Height measurement delay (msec)

This is the number of msec that the Height measurements lag behind the inertial measurements.

Units	ms
Range	0 to 250
Increment	10
Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

EK3_HGT_I_GATE

Height measurement gate size

This sets the percentage number of standard deviations applied to the height measurement innovation consistency check. Decreasing it makes it more likely that good measurements will be rejected. Increasing it makes it more likely that bad measurements will be accepted. If EK3_GLITCH_RAD set to 0 the vertical position innovations will be clipped instead of rejected if they exceed the gate size and a smaller value of EK3_HGT_I_GATE not exceeding 300 is recommended to limit the effect of height sensor transient errors.

Range	100 to 1000
Increment	25
User level	Advanced

EK3_HRT_FILT

Height rate filter crossover frequency

Specifies the crossover frequency of the complementary filter used to calculate the output predictor height rate derivative.

Units	Hz
Range	0.1 to 30.0

EK3_IMU_MASK

Bitmask of active IMUs

1 byte bitmap of IMUs to use in EKF3. A separate instance of EKF3 will be started for each IMU selected. Set to 1 to use the first IMU only (default), set to 2 to use the second IMU only, set to 3 to use the first and second IMU. Additional IMU’s can be used up to a maximum of 6 if memory and processing resources permit. There may be insufficient memory and processing resources to run multiple instances. If this occurs EKF3 will fail to start.

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Bitmask

Value	Meaning
0	FirstIMU
1	SecondIMU
2	ThirdIMU
3	FourthIMU
4	FifthIMU
5	SixthIMU

EK3_LOG_LEVEL

Logging Level

Determines how verbose the EKF3 streaming logging is. A value of 0 provides full logging(default), a value of 1 only XKF4 scaled innovations are logged, a value of 2 both XKF4 and GSF are logged, and a value of 3 disables all streaming logging of EKF3.

Range	0 to 3
Increment	1
User level	Advanced

EK3_MAGB_P_NSE

Body magnetic field process noise (gauss/s)

This state process noise controls the growth of body magnetic field state error estimates. Increasing it makes magnetometer bias error estimation faster and noisier.

Units	Gauss/s
Range	0.00001 to 0.01
User level	Advanced

EK3_MAGE_P_NSE

Earth magnetic field process noise (gauss/s)

This state process noise controls the growth of earth magnetic field state error estimates. Increasing it makes earth magnetic field estimation faster and noisier.

Units	Gauss/s
Range	0.00001 to 0.01
User level	Advanced

EK3_MAG_CAL

Magnetometer default fusion mode

This determines when the filter will use the 3-axis magnetometer fusion model that estimates both earth and body fixed magnetic field states and when it will use a simpler magnetic heading fusion model that does not use magnetic field states. The 3-axis magnetometer fusion is only suitable for use when the external magnetic field environment is stable. EK3_MAG_CAL = 0 uses heading fusion on ground, 3-axis fusion in-flight, and is the default setting for Plane users. EK3_MAG_CAL = 1 uses 3-axis fusion only when manoeuvring. EK3_MAG_CAL = 2 uses heading fusion at all times, is recommended if the external magnetic field is varying and is the default for rovers. EK3_MAG_CAL = 3 uses heading fusion on the ground and 3-axis fusion after the first in-air field and yaw reset has completed, and is the default for copters. EK3_MAG_CAL = 4 uses 3-axis fusion at all times. EK3_MAG_CAL = 5 uses an external yaw sensor with simple heading fusion. NOTE : Use of simple heading magnetometer fusion makes vehicle compass calibration and alignment errors harder for the EKF to detect which reduces the sensitivity of the Copter EKF failsafe algorithm. NOTE: The fusion mode can be forced to 2 for specific EKF cores using the EK3_MAG_MASK parameter. EK3_MAG_CAL = 6 uses an external yaw sensor with fallback to compass when the external sensor is not available if we are flying. NOTE: The fusion mode can be forced to 2 for specific EKF cores using the EK3_MAG_MASK parameter. NOTE: limited operation without a magnetometer or any other yaw sensor is possible by setting all COMPASS_USE, COMPASS_USE2, COMPASS_USE3, etc parameters to 0 and setting COMPASS_ENABLE to 0. If this is done, the EK3_GSF_RUN and EK3_GSF_USE masks must be set to the same as EK3_IMU_MASK. A yaw angle derived from IMU and GPS velocity data using a Gaussian Sum Filter (GSF) will then be used to align the yaw when flight commences and there is sufficient movement.

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Values

Value	Meaning
0	When flying
1	When manoeuvring
2	Never
3	After first climb yaw reset
4	Always
5	Use external yaw sensor (Deprecated in 4.1+ see EK3_SRCn_YAW)
6	External yaw sensor with compass fallback (Deprecated in 4.1+ see EK3_SRCn_YAW)

EK3_MAG_EF_LIM

EarthField error limit

This limits the difference between the learned earth magnetic field and the earth field from the world magnetic model tables. A value of zero means to disable the use of the WMM tables.

Units	mGauss
Range	0 to 500
User level	Advanced

EK3_MAG_I_GATE

Magnetometer measurement gate size

This sets the percentage number of standard deviations applied to the magnetometer measurement innovation consistency check. Decreasing it makes it more likely that good measurements will be rejected. Increasing it makes it more likely that bad measurements will be accepted.

Range	100 to 1000
Increment	25
User level	Advanced

EK3_MAG_MASK

Bitmask of active EKF cores that will always use heading fusion

1 byte bitmap of EKF cores that will disable magnetic field states and use simple magnetic heading fusion at all times. This parameter enables specified cores to be used as a backup for flight into an environment with high levels of external magnetic interference which may degrade the EKF attitude estimate when using 3-axis magnetometer fusion. NOTE : Use of a different magnetometer fusion algorithm on different cores makes unwanted EKF core switches due to magnetometer errors more likely.

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Bitmask

Value	Meaning
0	FirstEKF
1	SecondEKF
2	ThirdEKF
3	FourthEKF
4	FifthEKF
5	SixthEKF

EK3_MAG_M_NSE

Magnetometer measurement noise (Gauss)

This is the RMS value of noise in magnetometer measurements. Increasing it reduces the weighting on these measurements.

Units	Gauss
Range	0.01 to 0.5
Increment	0.01
User level	Advanced

EK3_NOAID_M_NSE

Non-GPS operation position uncertainty (m)

This sets the amount of position variation that the EKF allows for when operating without external measurements (eg GPS or optical flow). Increasing this parameter makes the EKF attitude estimate less sensitive to vehicle manoeuvres but more sensitive to IMU errors.

Units	m
Range	0.5 to 50.0
User level	Advanced

EK3_OGNM_TEST_SF

On ground not moving test scale factor

This parameter is adjust the sensitivity of the on ground not moving test which is used to assist with learning the yaw gyro bias and stopping yaw drift before flight when operating without a yaw sensor. Bigger values allow the detection of a not moving condition with noiser IMU data. Check the XKFM data logged when the vehicle is on ground not moving and adjust the value of OGNM_TEST_SF to be slightly higher than the maximum value of the XKFM.ADR, XKFM.ALR, XKFM.GDR and XKFM.GLR test levels.

Range	1.0 to 10.0
Increment	0.5
User level	Advanced

EK3_OGN_HGT_MASK

Bitmask control of EKF reference height correction

When a height sensor other than GPS is used as the primary height source by the EKF, the position of the zero height datum is defined by that sensor and its frame of reference. If a GPS height measurement is also available, then the height of the WGS-84 height datum used by the EKF can be corrected so that the height returned by the getLLH() function is compensated for primary height sensor drift and change in datum over time. The first two bit positions control when the height datum will be corrected. Correction is performed using a Bayes filter and only operates when GPS quality permits. The third bit position controls where the corrections to the GPS reference datum are applied. Corrections can be applied to the local vertical position or to the reported EKF origin height (default).

Reboot required	Yes — the change takes effect after a reboot.
User level	Advanced

Bitmask

Value	Meaning
0	Correct when using Baro height
1	Correct when using range finder height
2	Apply corrections to local position

EK3_OPTIONS

Optional EKF behaviour

EKF optional behaviour. Bit 0 (JammingExpected): Setting JammingExpected will change the EKF behaviour such that if dead reckoning navigation is possible it will require the preflight alignment GPS quality checks controlled by EK3_GPS_CHECK and EK3_CHECK_SCALE to pass before resuming GPS use if GPS lock is lost for more than 2 seconds to prevent bad position estimate. Bit 1 (Manual lane switching): DANGEROUS – If enabled, this disables automatic lane switching. If the active lane becomes unhealthy, no automatic switching will occur. Users must manually set EK3_PRIMARY to change lanes. No health checks will be performed on the selected lane. Use with extreme caution. Bit 2 (Optflow may use terrain alt): Terrain SRTM data will be used if the vehicle climbs above the rangefinder’s range allowing optical flow to be used at higher altitudes.

User level

Advanced

Bitmask

Value	Meaning
0	JammingExpected
1	ManualLaneSwitching
2	Optflow may use terrain alt

EK3_POSNE_M_NSE

GPS horizontal position measurement noise (m)

This sets the GPS horizontal position observation noise. Increasing it reduces the weighting of GPS horizontal position measurements.

Units	m
Range	0.1 to 10.0
Increment	0.1
User level	Advanced

EK3_POS_I_GATE

GPS position measurement gate size

This sets the percentage number of standard deviations applied to the GPS position measurement innovation consistency check. Decreasing it makes it more likely that good measurements will be rejected. Increasing it makes it more likely that bad measurements will be accepted. If EK3_GLITCH_RAD has been set to 0 the horizontal position innovations will be clipped instead of rejected if they exceed the gate size so a smaller value of EK3_POS_I_GATE not exceeding 300 is recommended to limit the effect of GPS transient errors.

Range	100 to 1000
Increment	25
User level	Advanced

EK3_PRIMARY

Primary core number

The core number (index in IMU mask) that will be used as the primary EKF core on startup. While disarmed the EKF will force the use of this core. A value of 0 corresponds to the first IMU in EK3_IMU_MASK.

Range	0 to 2
Increment	1
User level	Advanced

EK3_RNG_I_GATE

Range finder measurement gate size

This sets the percentage number of standard deviations applied to the range finder innovation consistency check. Decreasing it makes it more likely that good measurements will be rejected. Increasing it makes it more likely that bad measurements will be accepted.

Range	100 to 1000
Increment	25
User level	Advanced

EK3_RNG_M_NSE

Range finder measurement noise (m)

This is the RMS value of noise in the range finder measurement. Increasing it reduces the weighting on this measurement.

Units	m
Range	0.1 to 10.0
Increment	0.1
User level	Advanced

EK3_RNG_USE_HGT

Range finder switch height percentage

Range finder can be used as the primary height source when below this percentage of its maximum range (see RNGFNDx_MAX) and the primary height source is Baro or GPS (see EK3_SRCx_POSZ). This feature should not be used for terrain following as it is designed for vertical takeoff and landing with climb above the range finder use height before commencing the mission, and with horizontal position changes below that height being limited to a flat region around the takeoff and landing point.

Units	%
Range	-1 to 70
Increment	1
User level	Advanced

EK3_RNG_USE_SPD

Range finder max ground speed

The range finder will not be used as the primary height source when the horizontal ground speed is greater than this value.

Units	m/s
Range	2.0 to 6.0
Increment	0.5
User level	Advanced

EK3_TAU_OUTPUT

Output complementary filter time constant (centi-sec)

Sets the time constant of the output complementary filter/predictor in centi-seconds.

Units	cs
Range	10 to 50
Increment	5
User level	Advanced

EK3_TERR_GRAD

Maximum terrain gradient

Specifies the maximum gradient of the terrain below the vehicle when it is using range finder as a height reference

Range	0 to 0.2
Increment	0.01
User level	Advanced

EK3_VELD_M_NSE

GPS vertical velocity measurement noise (m/s)

This sets a lower limit on the speed accuracy reported by the GPS receiver that is used to set vertical velocity observation noise. If the model of receiver used does not provide a speed accurcy estimate, then the parameter value will be used. Increasing it reduces the weighting of the GPS vertical velocity measurements.

Units	m/s
Range	0.05 to 5.0
Increment	0.05
User level	Advanced

EK3_VELNE_M_NSE

GPS horizontal velocity measurement noise (m/s)

This sets a lower limit on the speed accuracy reported by the GPS receiver that is used to set horizontal velocity observation noise. If the model of receiver used does not provide a speed accurcy estimate, then the parameter value will be used. Increasing it reduces the weighting of the GPS horizontal velocity measurements.

Units	m/s
Range	0.05 to 5.0
Increment	0.05
User level	Advanced

EK3_VEL_I_GATE

GPS velocity innovation gate size

This sets the percentage number of standard deviations applied to the GPS velocity measurement innovation consistency check. Decreasing it makes it more likely that good measurements will be rejected. Increasing it makes it more likely that bad measurements will be accepted. If EK3_GLITCH_RAD set to 0 the velocity innovations will be clipped instead of rejected if they exceed the gate size and a smaller value of EK3_VEL_I_GATE not exceeding 300 is recommended to limit the effect of GPS transient errors.

Range	100 to 1000
Increment	25
User level	Advanced

EK3_VIS_VERR_MAX

Visual odometry maximum velocity error

This is the 1-STD odometry velocity observation error that will be assumed when minimum quality is reported by the sensor. When quality is between max and min, the error will be calculated using linear interpolation between VIS_VERR_MIN and VIS_VERR_MAX.

Units	m/s
Range	0.5 to 5.0
Increment	0.1
User level	Advanced

EK3_VIS_VERR_MIN

Visual odometry minimum velocity error

This is the 1-STD odometry velocity observation error that will be assumed when maximum quality is reported by the sensor. When quality is between max and min, the error will be calculated using linear interpolation between VIS_VERR_MIN and VIS_VERR_MAX.

Units	m/s
Range	0.05 to 0.5
Increment	0.05
User level	Advanced

EK3_WENC_VERR

Wheel odometry velocity error

This is the 1-STD odometry velocity observation error that will be assumed when wheel encoder data is being fused.

Units	m/s
Range	0.01 to 1.0
Increment	0.1
User level	Advanced

EK3_WIND_PSCALE

Height rate to wind process noise scaler

This controls how much the process noise on the wind states is increased when gaining or losing altitude to take into account changes in wind speed and direction with altitude. Increasing this parameter increases how rapidly the wind states adapt when changing altitude, but does make wind velocity estimation noiser.

Range	0.0 to 2.0
Increment	0.1
User level	Advanced

EK3_WIND_P_NSE

Wind velocity process noise (m/s^2)

This state process noise controls the growth of wind state error estimates. Increasing it makes wind estimation faster and noisier.

Units	m/s/s
Range	0.01 to 2.0
Increment	0.1
User level	Advanced

EK3_YAW_I_GATE

Yaw measurement gate size

This sets the percentage number of standard deviations applied to the magnetometer yaw measurement innovation consistency check. Decreasing it makes it more likely that good measurements will be rejected. Increasing it makes it more likely that bad measurements will be accepted.

Range	100 to 1000
Increment	25
User level	Advanced

EK3_YAW_M_NSE

Yaw measurement noise (rad)

This is the RMS value of noise in yaw measurements from the magnetometer. Increasing it reduces the weighting on these measurements.

Units	rad
Range	0.05 to 1.0
Increment	0.05
User level	Advanced