AHRS_ parameters¶

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

AHRS_COMP_BETA¶

AHRS Velocity Complementary Filter Beta Coefficient

This controls the time constant for the cross-over frequency used to fuse AHRS (airspeed and heading) and GPS data to estimate ground velocity. Time constant is 0.1/beta. A larger time constant will use GPS data less and a small time constant will use air data less.

Range	`0.001` to `0.5`
Increment	`0.01`
User level	Advanced

AHRS_CUSTOM_PIT¶

Board orientation pitch offset

Autopilot mounting position pitch offset. Positive values = pitch up, negative values = pitch down. This parameter is only used when AHRS_ORIENTATION is set to CUSTOM.

Units	`deg`
Range	`-180` to `180`
Increment	`1`
User level	Advanced

AHRS_CUSTOM_ROLL¶

Board orientation roll offset

Autopilot mounting position roll offset. Positive values = roll right, negative values = roll left. This parameter is only used when AHRS_ORIENTATION is set to CUSTOM.

Units	`deg`
Range	`-180` to `180`
Increment	`1`
User level	Advanced

AHRS_CUSTOM_YAW¶

Board orientation yaw offset

Autopilot mounting position yaw offset. Positive values = yaw right, negative values = yaw left. This parameter is only used when AHRS_ORIENTATION is set to CUSTOM.

Units	`deg`
Range	`-180` to `180`
Increment	`1`
User level	Advanced

AHRS_EKF_TYPE¶

Use NavEKF Kalman filter for attitude and position estimation

This controls which NavEKF Kalman filter version is used for attitude and position estimation

User level

Advanced

Values¶

Value	Meaning
`0`	Disabled
`2`	Enable EKF2
`3`	Enable EKF3
`10`	Sim
`11`	ExternalAHRS

AHRS_GPS_GAIN¶

AHRS GPS gain

This controls how much to use the GPS to correct the attitude. This should never be set to zero for a plane as it would result in the plane losing control in turns. For a plane please use the default value of 1.0.

Range	`0.0` to `1.0`
Increment	`0.01`
User level	Advanced

AHRS_GPS_MINSATS¶

AHRS GPS Minimum satellites

Minimum number of satellites visible to use GPS for velocity based corrections attitude correction. This defaults to 6, which is about the point at which the velocity numbers from a GPS become too unreliable for accurate correction of the accelerometers.

Range	`0` to `10`
Increment	`1`
User level	Advanced

AHRS_GPS_USE¶

AHRS use GPS for DCM navigation and position-down

This controls whether to use dead-reckoning or GPS based navigation. If set to 0 then the GPS won’t be used for navigation, and only dead reckoning will be used. A value of zero should never be used for normal flight. Currently this affects only the DCM-based AHRS: the EKF uses GPS according to its own parameters. A value of 2 means to use GPS for height as well as position - both in DCM estimation and when determining altitude-above-home.

User level

Advanced

Values¶

Value	Meaning
`0`	Disabled
`1`	Use GPS for DCM position
`2`	Use GPS for DCM position and height

AHRS_OPTIONS¶

Optional AHRS behaviour

This controls optional AHRS behaviour. Setting DisableDCMFallbackFW will change the AHRS behaviour for fixed wing aircraft in fly-forward flight to not fall back to DCM when the EKF stops navigating. Setting DisableDCMFallbackVTOL will change the AHRS behaviour for fixed wing aircraft in non fly-forward (VTOL) flight to not fall back to DCM when the EKF stops navigating. Setting DontDisableAirspeedUsingEKF disables the EKF based innovation check for airspeed consistency. Setting AutoRecordOrigin will auto-save the EKF origin to parameters when it becomes valid.

User level

Advanced

Bitmask¶

Value	Meaning
`0`	DisableDCMFallbackFW
`1`	DisableDCMFallbackVTOL
`2`	DontDisableAirspeedUsingEKF
`3`	RecordOrigin
`4`	UseRecordedOriginForNonGPS

AHRS_ORIENTATION¶

Board Orientation

Overall board orientation relative to the standard orientation for the board type. This rotates the IMU and compass readings to allow the board to be oriented in your vehicle at any 90 or 45 degree angle. The label for each option is specified in the order of rotations for that orientation. This option takes affect on next boot. After changing you will need to re-level your vehicle. Firmware versions 4.2 and prior can use a CUSTOM (100) rotation to set the AHRS_CUSTOM_ROLL/PIT/YAW angles for AHRS orientation. Later versions provide two general custom rotations which can be used, Custom 1 and Custom 2, with CUST_ROT1_ROLL/PIT/YAW or CUST_ROT2_ROLL/PIT/YAW angles.

User level

Advanced

Values¶

Value	Meaning
`0`	None
`1`	Yaw45
`2`	Yaw90
`3`	Yaw135
`4`	Yaw180
`5`	Yaw225
`6`	Yaw270
`7`	Yaw315
`8`	Roll180
`9`	Yaw45Roll180
`10`	Yaw90Roll180
`11`	Yaw135Roll180
`12`	Pitch180
`13`	Yaw225Roll180
`14`	Yaw270Roll180
`15`	Yaw315Roll180
`16`	Roll90
`17`	Yaw45Roll90
`18`	Yaw90Roll90
`19`	Yaw135Roll90
`20`	Roll270
`21`	Yaw45Roll270
`22`	Yaw90Roll270
`23`	Yaw135Roll270
`24`	Pitch90
`25`	Pitch270
`26`	Yaw90Pitch180
`27`	Yaw270Pitch180
`28`	Pitch90Roll90
`29`	Pitch90Roll180
`30`	Pitch90Roll270
`31`	Pitch180Roll90
`32`	Pitch180Roll270
`33`	Pitch270Roll90
`34`	Pitch270Roll180
`35`	Pitch270Roll270
`36`	Yaw90Pitch180Roll90
`37`	Yaw270Roll90
`38`	Yaw293Pitch68Roll180
`39`	Pitch315
`40`	Pitch315Roll90
`42`	Roll45
`43`	Roll315
`100`	Custom 4.1 and older
`101`	Custom 1
`102`	Custom 2

AHRS_ORIGIN_ALT¶

AHRS last origin altitude

AHRS last origin altitude in meters

Range	`-200` to `5000`
User level	Advanced

AHRS_ORIGIN_LAT¶

AHRS last origin latitude

AHRS last origin latitude in degrees

Range	`-180` to `180`
Increment	`1`
User level	Advanced

AHRS_ORIGIN_LON¶

AHRS last origin longitude

AHRS last origin longitude in degrees

Range	`-180` to `180`
User level	Advanced

AHRS_RP_P¶

AHRS RP_P

This controls how fast the accelerometers correct the attitude

Range	`0.1` to `0.4`
Increment	`0.01`
User level	Advanced

AHRS_TRIM_X¶

AHRS Trim Roll

Compensates for the roll angle difference between the control board and the frame. Positive values make the vehicle roll right.

Units	`rad`
Range	`-0.1745` to `+0.1745`
Increment	`0.01`
User level	Standard

AHRS_TRIM_Y¶

AHRS Trim Pitch

Compensates for the pitch angle difference between the control board and the frame. Positive values make the vehicle pitch up/back.

Units	`rad`
Range	`-0.1745` to `+0.1745`
Increment	`0.01`
User level	Standard

AHRS_TRIM_Z¶

AHRS Trim Yaw

Not Used

Units	`rad`
Range	`-0.1745` to `+0.1745`
Increment	`0.01`
User level	Advanced

AHRS_WIND_MAX¶

Maximum wind

This sets the maximum allowable difference between ground speed and airspeed. A value of zero means to use the airspeed as is. This allows the plane to cope with a failing airspeed sensor by clipping it to groundspeed plus/minus this limit. See ARSPD_OPTIONS and ARSPD_WIND_MAX to disable airspeed sensors.

Units	`m/s`
Range	`0` to `127`
Increment	`1`
User level	Advanced

AHRS_YAW_P¶

Yaw P

This controls the weight the compass or GPS has on the heading. A higher value means the heading will track the yaw source (GPS or compass) more rapidly.

Range	`0.1` to `0.4`
Increment	`0.01`
User level	Advanced