Commit Graph

60 Commits

Author SHA1 Message Date
Paul Riseborough 24d8cc62e2 AP_NavEKF2: rework yaw and magnetic heading reset logic
Splits in-flight yaw alignment completed status into separate yaw and magnetic field flags.
Reduce the number of places where decisions to perform a yaw and field reset are made.
Don't perform a reset unless there is is data in the buffer
Don't use 3-axis fusion if the field states still need to be reset.
When starting 3-axis fusion request a reset if not previously performed.
Ensure magnetometer and GPs heading resets are alwasy perfomred with data at teh correct time horizon.
2016-05-31 16:12:53 +10:00
Paul Riseborough de15928921 AP_NavEKF2: prevent potential arithmetic error in declination fusion 2016-05-27 09:00:41 +10:00
Paul Riseborough 11c6ea7ef6 AP_NavEKF2: attitude co-variance reset for all post alignment yaw resets
Whenever the yaw angle is changed, the correlation with other state errors will be incorrect and the terms should be zeroed.
2016-05-27 09:00:41 +10:00
Paul Riseborough fe9ddfdfeb AP_NavEKF2: remove code that prevents attitude updates after mag reset
This code assumes a vehicle is close to level and will not work for all vehicle types. It will be replaced by a different method.
2016-05-27 09:00:40 +10:00
Paul Riseborough fe85c68344 AP_NavEKF2: move yaw reset for no compass case
Should not be in a function that performs reset on magnetic field states
2016-05-27 09:00:40 +10:00
Paul Riseborough 74121fdaeb AP_NavEKF2: fix bug preventing in-flight alignment 2016-05-21 15:13:53 +10:00
Paul Riseborough 9aa3cdfaae AP_NavEKF2: Update GPS yaw re-alignment function
Updates to support initial alignment without magnetometer
2016-05-21 15:13:53 +10:00
Paul Riseborough e3c966661b AP_NavEKF2: Remove unnecessary variance reset
This reset is unnecessary give that a synthetic yaw angle is fused at a low rate to prevent variances from becoming badly conditioned.
2016-05-21 15:13:53 +10:00
Paul Riseborough 1179c08473 AP_NavEKF2: Handle case where we are in-flight and haven't yet aligned the yaw
This happens if planes are flown without a compass
2016-05-21 15:13:53 +10:00
Paul Riseborough 581c1aa0d4 AP_NavEKF2: Adjust attitude variance values used after a heading reset
Because these errors are in body frame, a spherical error should be used to accommodate different orientations
2016-05-21 15:13:53 +10:00
Paul Riseborough 64a8153b68 AP_NavEKF2: update function name
The primary purpose of this function is re-alignment
2016-05-21 15:13:52 +10:00
Paul Riseborough 42da33593d AP_NavEKF2: fix yaw fusion numerical health reporting 2016-05-21 15:13:51 +10:00
Paul Riseborough 6eb9d43507 AP_NavEKF2: add numerical error checking and isolation to mag decl fusion 2016-05-21 15:13:51 +10:00
Paul Riseborough b325c5faeb AP_NavEKF2: add error checking and isolation to mag heading fusion 2016-05-21 15:13:51 +10:00
Paul Riseborough a0b1dc5325 AP_NavEKF2: add error checking and isolation to 3D amg fusion 2016-05-21 15:13:51 +10:00
Ricardo de Almeida Gonzaga 64d14356b9 AP_NavEKF2: Fix typos 2016-05-13 19:20:06 -03:00
dgrat 41661f815f AP_Math: Replace the pythagorous* functions with a variadic template
The new function can deal with a variable number of function parameters.
Additionally, I renamed the functions to norm(), because this is the
standard name used in several other projects.
2016-05-10 11:41:26 -03:00
Paul Riseborough 1ecc206eee AP_NavEKF2: Allow use in planes without a magnetometer
Implements the following techniques to enable planes to operate without magnetometers.

1) When on ground with mag use inhibited, a synthetic heading equal to current heading is fused to prevent uncontrolled covariance growth.
2) When transitioning to in-flight, the delta between inertial and GPS velocity vector is used to align the yaw.
3) The yaw gyro bias state variance is reset following an in-flight heading reset to enable the yaw gyro bias to be learned faster.
2016-04-15 08:31:47 +10:00
Paul Riseborough 6d9ba8c527 AP_NavEKF2: Improve protection against ground based mag interference
Reset the mag field states and yaw earlier than the normal 5m height threshold if toilet bowling is detected.
2016-03-17 10:55:11 +11:00
Paul Riseborough 2888bdd6d5 AP_NavEKF: Protect against possible div by 0 2016-03-01 10:08:47 -03:00
Paul Riseborough 7d6b926749 AP_NavEKF2: Improved magnetic heading fusion
Use an Euler yaw heading that switches between a 321 and 312 rotation
sequence to avoid areas of singularity.  Using Euler yaw decouples the
observation from the roll and pitch states and prevents magnetic
disturbances from affecting roll and pitch via the magnetometer fusion
process.
2016-03-01 10:08:47 -03:00
dgrat 5148e41c1a AP_Math: Cleaned macro definitions
Moved Definitions into a separate header. Replaced PI with M_PI and
removed the M_PI_*_F macros.
2016-02-27 02:51:33 -03:00
Paul Riseborough 7459bfb96b AP_NavEKF2: Eliminate simple compass fusion singularities near +-90 deg pitch
The use of yaw angle fusion during startup and ground operation causes problems with tail-sitter vehicle types.
Instead of observing an Euler yaw angle, we now observe the yaw angle obtained by projecting the measured magnetic field onto the the horizontal plain.
This avoids the singularities associated with the observation of Euler yaw angle.
2016-02-22 16:29:36 +11:00
Paul Riseborough 4aefe1caee AP_NavEKF2: Fix sign error in magnetic heading innovation calculation 2016-02-20 08:55:48 +11:00
Paul Riseborough 047e9fabaf AP_NavEKF2: Fix bug in simple heading fusion
The innovation calculation should have been updated when the heading fusion maths was updated.

We now use a direct heading or yaw angle measurement in the derivation, not the difference between observed and published declination.
2016-02-19 15:35:11 +09:00
Paul Riseborough d3c9a0aef1 AP_NavEKF: Limit heading innovations after the consistency check 2016-02-18 08:53:47 +09:00
Paul Riseborough 6a34e4c384 AP_NavEKF2: Fix bug in magnetic heading and declination fusion equations.
The derivation incorrectly used a tan instead of an atan function. This applies the corrected auto-code.
2016-02-18 08:53:45 +09:00
Paul Riseborough 7e05646316 AP_NavEKF2: Improvements to non-GPS performance
Change to user adjustable fusion of constant position (as per legacy EKF) instead of constant velocity.
Enable user to specify use of 3-axis magnetometer fusion when operating without aiding.
Don't allow gyro scale factor learning without external aiding data as it can be unreliable
2016-02-18 08:53:41 +09:00
Paul Riseborough 20923da23a AP_NavEKF2: Allow tuning of non-GPS mode
Eliminate the use of horizontal position states during non-aiding operation to make it easier to tune.
Explicitly set the horizontal position associated Kalman gains to zero and the coresponding covariance entries to zero after avery fusion operation.
Make the horizontal velocity observation noise used during non-aiding operation adjustable.
Use a fixed value of velocity noise during initial alignment so that the flight peformance can be tuned without affecting the initial alignment.
2016-01-13 08:05:39 +11:00
Lucas De Marchi 2591261af6 Global: rename min and max macros to uppercase
The problem with using min() and max() is that they conflict with some
C++ headers. Name the macros in uppercase instead. We may go case by
case later converting them to be typesafe.

Changes generated with:

	git ls-files '*.cpp' '*.h' -z | xargs -0 sed -i 's/\([^_[:alnum:]]\)max(/\1MAX(/g'
	git ls-files '*.cpp' '*.h' -z | xargs -0 sed -i 's/\([^_[:alnum:]]\)min(/\1MIN(/g'
2015-12-01 16:28:09 -02:00
Siddharth Bharat Purohit b3c8dcee34 AP_NavEKF2: measurement buffer refactor 2015-11-23 19:34:50 +11:00
Paul Riseborough 20798316e1 AP_NavEKF2: fix bug in performance timer 2015-11-18 20:16:58 +09:00
Paul Riseborough f9cadaf15c AP_NavEKF2: Increase resolution of innovation consistency gate parameters
Also adds protection against setting the gate to a number that would casue numerical errors.
2015-11-18 11:39:53 +11:00
Paul Riseborough d820a538d5 AP_NavEKF2: Make magnetometer data available status global
This assists with debugging and makes it consistent with other measurements that are buffered
2015-11-18 11:18:46 +11:00
Paul Riseborough 9b82b2200c AP_NavEKF2: Fix plane in-flight yaw reset
The copter method was being used for plane and the plane method was not being run due to the change in flight status not being detected.
The plane reset method did not trigger if the EKF had already dragged the velocity states along with the GPS or could align to an incorrect heading.
The method has been reworked so that it resets to the GPS course, but only if there are inconsistent angles and large innovations.
To stop a failed magnetometer causing a loss of yaw reference later in flight, if all available sensors have been tried in flight and timed out, then no further magnetoemter data will be used
2015-11-16 09:05:42 +11:00
Paul Riseborough 577670ccee AP_NavEKF2: Reduce memory required by 6KB when running at 400Hz
Down-sample the IMU and output observer state data to 100Hz for storage in the buffer.
This reduces storage requirements for Copter by 75% or 6KB
It does not affect memory required by plane which already uses short buffers due to its 50Hz execution rate.
This means that the EKF filter operations operate at a maximum rate of 100Hz.
The output observer continues to operate at 400Hz and coning and sculling corrections are applied during the down-sampling so there is no loss of accuracy.
2015-11-10 15:51:18 +11:00
Paul Riseborough 6deabe28c2 AP_NavEKF2: Require all magnetometer axes to pass innovation test
The original design intent was to require all axes to pass because severe errors are rarely constrained to a single axis.
This was not achieved with the previous implementation.
These changes move the innovation consistency checks for all three axes to the top before any axes are fused.
Unnecessary performance timers have been removed.
2015-11-09 22:07:09 +11:00
Andrew Tridgell 2ab2afc86a AP_NavEKF2: added EK2_IMU_MASK for multiple IMUs
no voting between multiple IMUs yet
2015-11-06 10:42:58 +11:00
Paul Riseborough aa14de9d39 AP_NavEKF2: Fix failure to start mag cal due to gyro noise
Vibration in the 400Hz delta angles could cause the angular rate condition check for in-flight magnetic field alignment to fail.
The symptons were failure to start magnetic field learning as expected when EK2_MAG_CAL=3 was set.
2015-11-02 14:12:17 +11:00
Paul Riseborough b15bf3243e AP_NavEKF2: Remove potential for division by zero 2015-10-30 15:34:26 +09:00
Paul Riseborough 5533a9a149 AP_NavEKF2: Add improved health monitoring when using simple compass yaw fusion 2015-10-30 15:34:23 +09:00
Paul Riseborough f539b597a3 AP_NavEKF2: Improve initialisation of magnetic field learning
Use the more robust, but less accurate compass heading fusion up to 5m altitude
Wait for the magnetometer data fusion time offset to be correct before using data to reset states
Don't reset magnetic field states if the vehicle is rotating rapidly as timing offsets will produce large errors
When doing the yaw angle reset, apply the reset increment to all quaternions stored in the output buffer to avoid transients produced by yaw rotations and the 0.25 second fusion time horizon offset.
Only do the one yaw and mag reset at 5m, not two at 1.5 and 5.0m
Always re-do the yaw and mag reset when leaving the ground.
2015-10-30 15:34:20 +09:00
Paul Riseborough e692e30988 AP_NavEKF2: Reduce allowance for magnetometer timing errors
The previous gain from rate to magnetometer error was excessive. The revised value is equivalent to a magnetic field length of 0.5 with a timing uncertainty of 0.01 sec
2015-10-26 08:05:15 +11:00
Paul Riseborough 4c5ba60578 AP_NavEKF2: Remove dead code 2015-10-26 08:05:15 +11:00
Paul Riseborough 1e7ac873b9 AP_NavEKF2: Improve handling of GPS loss and recovery for planes
Extended GPS loss can result in the earth field states becoming  rotated and making it difficult for the EKF to recover its heading when GPS is regained.
During prolonged GPS outages, the position covariance can become large enough to cause the reset function to continually activate. This is fixed by ensuring that position covariances are always reset when the position is reset.
The innovation variance was being used incorrectly instead of the state variance to trigger the glitch reset.
2015-10-24 07:17:11 +11:00
Paul Riseborough 5eb7cf1fbf AP_NavEKF: Reduce roll/pitch disturbance when magnetic field is reset
Because we have changed the yaw angle and have taken a point sample on the magnetic field, covariances associated with the magnetic field states will be invalid and subsequent innovations could cause an unwanted disturbance in roll and pitch.
The reset of the Euler angles to a new yaw orientation was being done using roll and pitch from the output observer states, not the EKF state vector which meant that when roll and pitch were changing, the reset to a new yaw angle would also cause a roll and pitch disturbance.
2015-10-23 19:04:30 +11:00
Andrew Tridgell cb0f7cb370 NavEKF2: use new perf counter API 2015-10-20 18:16:15 +11:00
Paul Riseborough 60c2e81d19 AP_NavEKF2: Apply optimisations to declination fusion covariance update
These are the same type of optimisations that were successful with the magnetometer fusion
2015-10-20 15:21:41 +11:00
Paul Riseborough b5e43288d4 AP_NavEKF2: Down to 12 from 14 usec for perf test[8] 2015-10-20 15:21:40 +11:00
Andrew Tridgell d1dfd5fd01 AP_NavEKF2: use common header for optimisation level and irq disable 2015-10-20 15:21:40 +11:00