Subsystem/ahrs - Revision history

Openuas at 07:55, 14 April 2020

2020-04-14T07:55:33Z

← Older revision		Revision as of 01:55, 14 April 2020
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	=== Update geomagnetic field vector based on GPS ===		=== Update geomagnetic field vector based on GPS ===
	You can also add the [http://docs.paparazziuav.org/latest/module__geo_mag.html geo_mag.xml module], which will update the normalized magnetic field at startup using ~~GPS~~ fix:		You can also add the [http://docs.paparazziuav.org/latest/module__geo_mag.html geo_mag.xml module], which will update the normalized magnetic field at startup using GNSS data of where you get the position fix:
	{{Box Code\|conf/airframes/myplane.xml\|		{{Box Code\|conf/airframes/myplane.xml\|
	<source lang="xml">		<source lang="xml">
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	</source>		</source>
	}}		}}

			This way, wherever you fly on the planet, no need to update your airframe file every time.

	== Enabling External Sensors ==		== Enabling External Sensors ==

Openuas: /* AHRS subsystem */

2017-04-03T05:26:20Z

AHRS subsystem

← Older revision		Revision as of 23:26, 2 April 2017
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	\|'''[[Subsystem/ahrs#Kalman_Filter_Quaternion\|float_mlkf]]''' \|\| floating \|\| rotorcraft \|\|		\|'''[[Subsystem/ahrs#Kalman_Filter_Quaternion\|float_mlkf]]''' \|\| floating \|\| rotorcraft \|\|
	\|-		\|-
	\| '''[[Subsystem/ahrs#Infrared\|infrared]]''' \|\| \|\| ~~fixedwing?~~ \|\|		\| '''[[Subsystem/ahrs#Infrared\|infrared]]''' \|\| \|\| all \|\|
	\|-		\|-
	\| '''[[Subsystem/ahrs#Vectornav\|vectornav]]''' \|\| \|\| all \|\| external		\| '''[[Subsystem/ahrs#Vectornav\|vectornav]]''' \|\| \|\| all \|\| external

Openuas: /* AHRS subsystem */

2017-04-03T05:25:42Z

AHRS subsystem

← Older revision		Revision as of 23:25, 2 April 2017
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	\|'''[[Subsystem/ahrs#Complementary_Quaternion_.28fixed_point.29\|int_cmpl_quat]]''' \|\| fixed \|\| all \|\|		\|'''[[Subsystem/ahrs#Complementary_Quaternion_.28fixed_point.29\|int_cmpl_quat]]''' \|\| fixed \|\| all \|\|
	\|-		\|-
	\|'''[[Subsystem/ahrs#Complementary_Quaternion.2FRotation_Matrix_.28floating_point.29\|~~float_cmpl~~]]''' \|\| floating \|\| all \|\|		\|'''[[Subsystem/ahrs#Complementary_Quaternion.2FRotation_Matrix_.28floating_point.29\|float_cmpl_quat]]''' \|\| floating \|\| all \|\|
	\|-		\|-
	\|'''[[Subsystem/ahrs#DCM_.28floating_point.29\|float_dcm]]''' \|\| floating \|\| fixedwing \|\|		\|'''[[Subsystem/ahrs#DCM_.28floating_point.29\|float_dcm]]''' \|\| floating \|\| fixedwing \|\|

Podhrmic at 21:13, 5 March 2017

2017-03-05T21:13:22Z

← Older revision		Revision as of 15:13, 5 March 2017
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	\|-		\|-
	\| '''[[Subsystem/ahrs#Infrared\|infrared]]''' \|\| \|\| fixedwing? \|\|		\| '''[[Subsystem/ahrs#Infrared\|infrared]]''' \|\| \|\| fixedwing? \|\|
			\|-
			\| '''[[Subsystem/ahrs#Vectornav\|vectornav]]''' \|\| \|\| all \|\| external
	\|}		\|}

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	=== Infrared ===		=== Infrared ===
	For use with infrared sensors that detect aircraft attitude and the [[Module/infrared\| infrared module]].		For use with infrared sensors that detect aircraft attitude and the [[Module/infrared\| infrared module]].


			=== Vectornav ===
			Driver for the Vectornav VN-200 INS, running in AHRS mode (only orientation and rate estimates). See also [[Sensors/imu#Vectornav_VN-200]].

	== Local Magnetic Field ==		== Local Magnetic Field ==

Benelgizim: accelerometers do not measure attitude directly

2016-07-05T09:46:37Z

accelerometers do not measure attitude directly

← Older revision		Revision as of 03:46, 5 July 2016
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	To measure attitude angles, gyrometers measurements are integrated. The result of integration is accurate for short term, but gyro bias is accumulated, which results in long term errors (drift).		To measure attitude angles, gyrometers measurements are integrated. The result of integration is accurate for short term, but gyro bias is accumulated, which results in long term errors (drift).
	On the other hand, accelerometers can be used to ~~measure~~ angles ~~directly~~, but they suffer from noise due to vibrations. The measurement is then only accurate when averaged over a long term. Also, accelerometers alone are unable to give accurate angles when the vehicle is accelerating.		On the other hand, accelerometers can be used to infer pitch/roll angles utilizing gravity vector measurement, but they suffer from noise due to vibrations. The measurement is then only accurate when averaged over a long term. Also, accelerometers alone are unable to give accurate angles when the vehicle is accelerating.
	Complementary filter takes advantage of both sensors, using a low-pass filter on accelerometer readings and high pass filter on gyrometers readings, to estimate attitude angles.		Complementary filter takes advantage of both sensors, using a low-pass filter on accelerometer readings and high pass filter on gyrometers readings, to estimate attitude angles.
	* No danger of [http://en.wikipedia.org/wiki/Gimbal_lock gimbal lock], since quaternions are used.		* No danger of [http://en.wikipedia.org/wiki/Gimbal_lock gimbal lock], since quaternions are used.

IHaveADrone: minor spelling

2016-06-08T13:53:50Z

minor spelling

← Older revision		Revision as of 07:53, 8 June 2016
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	* NEW since [https://github.com/paparazzi/paparazzi/commit/b40da0ae56e861e088017c01426d0c4ed7c43350 v5.1_devel-455-gb40da0a]:		* NEW since [https://github.com/paparazzi/paparazzi/commit/b40da0ae56e861e088017c01426d0c4ed7c43350 v5.1_devel-455-gb40da0a]:
	** Proper scaling of corrections for 100Hz fixedwing or 500Hz for rotorcraft.		** Proper scaling of corrections for 100Hz fixedwing or 500Hz for rotorcraft.
	** Allow tuning of the accel and mag correction natural ~~freqency~~ and damping.		** Allow tuning of the accel and mag correction natural frequency and damping.
	** Tunable gravity_heuristic_factor to reduce accelerometer influence only when the vehicle is accelerating (norm of ax,ay,az ~ 9,81 m/s2).		** Tunable gravity_heuristic_factor to reduce accelerometer influence only when the vehicle is accelerating (norm of ax,ay,az ~ 9,81 m/s2).

Flixr: /* Complementary Quaternion (fixed point) */

2016-04-22T10:01:25Z

Complementary Quaternion (fixed point)

← Older revision		Revision as of 04:01, 22 April 2016
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	* Also suitable for fixedwings, but you need GPS.		* Also suitable for fixedwings, but you need GPS.
	** Compensation of centrifugal force via GPS speed (to fly in circles with a fixedwing).<br/>Enabled with AHRS_GRAVITY_UPDATE_COORDINATED_TURN which is set by default for a fixedwing firmware.		** Compensation of centrifugal force via GPS speed (to fly in circles with a fixedwing).<br/>Enabled with AHRS_GRAVITY_UPDATE_COORDINATED_TURN which is set by default for a fixedwing firmware.
	** ~~Uses~~ GPS course for heading estimation and ~~disable~~ magnetometer, add <source lang="xml" enclose="none"><configure name="USE_MAGNETOMETER" value="FALSE"/></source> if you want to be explicit.		** For fixedwing firmware, GPS course is used for heading estimation by default (and magnetometer disabled), add <source lang="xml" enclose="none"><configure name="USE_MAGNETOMETER" value="FALSE"/></source> if you want to be explicit.
			** To use magnetometer for heading: <source lang="xml" enclose="none"><configure name="USE_MAGNETOMETER" value="TRUE"/></source> and <source lang="xml" enclose="none"><configure name="AHRS_USE_GPS_HEADING" value="FALSE"/></source>


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	</source>		</source>
	}}		}}


	=== Complementary Quaternion/Rotation Matrix (floating point) ===		=== Complementary Quaternion/Rotation Matrix (floating point) ===

Flixr: /* Complementary Quaternion/Rotation Matrix (floating point) */

2015-12-16T11:52:11Z

Complementary Quaternion/Rotation Matrix (floating point)

← Older revision		Revision as of 05:52, 16 December 2015
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	* Estimates the gyro bias.		* Estimates the gyro bias.
	* By default uses magnetometer for heading for rotorcrafts.		* By default uses magnetometer for heading for rotorcrafts.
	* ~~You need to~~ define ~~either~~ ''AHRS_PROPAGATE_RMAT'' or ''AHRS_PROPAGATE_QUAT'' (select if the propagation is done in rotation matrix or quaternion representation).		* Choose either ''type="float_cmpl_rmat"'' or ''type="float_cmpl_quat"'', which define ''AHRS_PROPAGATE_RMAT'' or ''AHRS_PROPAGATE_QUAT'' respectively to select if the propagation is done in rotation matrix or quaternion representation.
	* For fixedwings:		* For fixedwings:
	** Compensation of centrifugal force via GPS speed (to fly in circles with a fixedwing).<br/>Enabled with AHRS_GRAVITY_UPDATE_COORDINATED_TURN which is set by default for a fixedwing firmware.		** Compensation of centrifugal force via GPS speed (to fly in circles with a fixedwing).<br/>Enabled with AHRS_GRAVITY_UPDATE_COORDINATED_TURN which is set by default for a fixedwing firmware.
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	* AHRS_PROPAGATE_LOW_PASS_RATES : apply a low pass filter on rotational velocity		* AHRS_PROPAGATE_LOW_PASS_RATES : apply a low pass filter on rotational velocity
	* AHRS_MAG_UPDATE_ALL_AXES : use mag to also update roll/pitch and not only yaw (not recommended in most cases)		* AHRS_MAG_UPDATE_ALL_AXES : use mag to also update roll/pitch and not only yaw (not recommended in most cases)
	* ~~AHRS_GRAVITY_UPDATE_NORM_HEURISTIC~~: ~~lower~~ the ~~gain of~~ the ~~gravity update based on a acceleration~~ norm ~~heuristic (e~~.g. ~~good for bungee takeoff)~~		* AHRS_GRAVITY_HEURISTIC_FACTOR: Default is 30. Reduce accelerometer cut-off frequency when the vehicle is accelerating: norm(ax,ay,az) ~ 9,81 m/s2. WARNING: when the IMU is not well damped, the norm of accelerometers never equals to 9,81 m/s2. As a result, the GRAVITY_HEURISTIC_FACTOR will reduce the accelerometer bandwith even if the vehicle is not accelerating. Set AHRS_GRAVITY_HEURISTIC_FACTOR = 0 in case of vibrations

	{{Box Code\|conf/airframes/myplane.xml\|		{{Box Code\|conf/airframes/myplane.xml\|
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	<firmware name="rotorcraft or fixedwing">		<firmware name="rotorcraft or fixedwing">
	...		...
	<subsystem name="ahrs" type="~~float_cmpl_rmat~~">		<subsystem name="ahrs" type="float_cmpl_quat">
	~~<define name="AHRS_PROPAGATE_QUAT"/~~>
	</subsystem>		</subsystem>
	</firmware>		</firmware>
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	The arithmetic is [http://en.wikipedia.org/wiki/Floating_point floating point] and is thus '''not''' suitable if the processor (on your board) has '''no''' [http://en.wikipedia.org/wiki/Floating_point_unit FPU].		The arithmetic is [http://en.wikipedia.org/wiki/Floating_point floating point] and is thus '''not''' suitable if the processor (on your board) has '''no''' [http://en.wikipedia.org/wiki/Floating_point_unit FPU].
	</p>		</p>


	=== DCM (floating point) ===		=== DCM (floating point) ===

Rijesh: Added how to enable ABI messages from external Mag

2015-07-29T22:25:08Z

Added how to enable ABI messages from external Mag

@@ Line 287: / Line 287: @@
 </source>
 }}
 [[Category:User_Documentation]] [[Category:Subsystems]]

IHaveADrone: /* AHRS subsystem */

2014-10-07T20:24:32Z

AHRS subsystem

← Older revision		Revision as of 14:24, 7 October 2014
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	{\| class="wikitable" style="text-align:center" border="1"		{\| class="wikitable" style="text-align:center" border="1"
	! ~~type~~ !! ~~point~~ type !! ~~firmwares~~ !! ~~notes~~		! Type !! Point type !! Firmwares !! Notes
	\|-		\|-
	\|''[[Subsystem/ahrs#Complementary_Quaternion_.28fixed_point.29\|int_cmpl_quat]]'' \|\| fixed \|\| all \|\|		\|'''[[Subsystem/ahrs#Complementary_Quaternion_.28fixed_point.29\|int_cmpl_quat]]''' \|\| fixed \|\| all \|\|
	\|-		\|-
	\|''[[Subsystem/ahrs#Complementary_Quaternion.2FRotation_Matrix_.28floating_point.29\|float_cmpl]]'' \|\| floating \|\| all \|\|		\|'''[[Subsystem/ahrs#Complementary_Quaternion.2FRotation_Matrix_.28floating_point.29\|float_cmpl]]''' \|\| floating \|\| all \|\|
	\|-		\|-
	\|''[[Subsystem/ahrs#DCM_.28floating_point.29\|float_dcm]]'' \|\| floating \|\| fixedwing \|\|		\|'''[[Subsystem/ahrs#DCM_.28floating_point.29\|float_dcm]]''' \|\| floating \|\| fixedwing \|\|
	\|-		\|-
	\|''[[Subsystem/ahrs#Complementary_Euler_.28fixed_point.29\|int_cmpl_euler]]'' \|\| fixed \|\| rotorcraft \|\|		\|'''[[Subsystem/ahrs#Complementary_Euler_.28fixed_point.29\|int_cmpl_euler]]''' \|\| fixed \|\| rotorcraft \|\|
	\|-		\|-
	\|''[[Subsystem/ahrs#Kalman_Filter_Quaternion\|float_mlkf]]'' \|\| floating \|\| rotorcraft \|\|		\|'''[[Subsystem/ahrs#Kalman_Filter_Quaternion\|float_mlkf]]''' \|\| floating \|\| rotorcraft \|\|
	\|-		\|-
	\| ''[[Subsystem/ahrs#Infrared\|infrared]]'' \|\| \|\| fixedwing? \|\|		\| '''[[Subsystem/ahrs#Infrared\|infrared]]''' \|\| \|\| fixedwing? \|\|
	\|}		\|}