- saves a small amount of work for the ekf2 selector in multi-EKF mode (visual_odometry_aligned now ignored)
 - helps to distinguish the origin/purpose from vehicle_odometry and vehicle_visual_odometry

In the predition step, the process variance was erroneously
multiplied by dt instead of dt^2. The default values are adjusted
accordingly to keep the same tuning for the default loop rate of 50Hz

Co-authored-by: Alexey Matveev <>

 - ekf2 can now run in multi-instance mode (currently up to 9 instances)
    - in multi mode all estimates are published to alternate topics (eg estimator_attitude instead of vehicle_attitude)
 - new ekf2 selector runs in multi-instance mode to monitor and compare all instances, selecting a primary (eg N x estimator_attitude => vehicle_attitude)
 - sensors module accel & gyro inconsistency checks are now relative to the mean of all instances, rather than the current primary (when active ekf2 selector is responsible for choosing primary accel & gyro)
 - existing consumers of estimator_status must check estimator_selector_status to select current primary instance status
 - ekf2 single instance mode is still fully supported and the default

Co-authored-by: Paul Riseborough <gncsolns@gmail.com>

This is the correct value for the most common optical flow sensor

This is important to align the flow with the IMU data and verify that
the compensation is properly done

    - sitl_gazebo in PX4/Firmware (945c17bc): https://github.com/PX4/sitl_gazebo/commit/4f03afc7def0b958e7567a35093bacf93dcc824f
    - sitl_gazebo current upstream: https://github.com/PX4/sitl_gazebo/commit/2451437c19ed9fcdf8a79990313e768c98aa15b6
    - Changes: https://github.com/PX4/sitl_gazebo/compare/4f03afc7def0b958e7567a35093bacf93dcc824f...2451437c19ed9fcdf8a79990313e768c98aa15b6

    2451437 2020-10-24 Igor Campos - fix #638 - geotagging plugin not working: subscribed to wrong topic
9f832e5 2020-10-09 JaeyoungLim - Add groundtruth plugin
dcae3ed 2020-09-29 JaeyoungLim - Switch tiltrotor to jinja templates
928169c 2020-09-28 JaeyoungLim - Move where the gps joint is being defined
60897b7 2020-08-24 JaeyoungLim - Fix tiltrotor model
9f82ad4 2020-10-22 JaeyoungLim - Move rover models to jinja templates (#629)
00d6f2f 2020-10-21 Thies Lennart Alff - Adding Model of BlueROV2 (heavy configuration) (#637)
b15784d 2020-10-19 Vojtech Spurny - gazebo_gps_plugin fix and enhancement (#635)

 - add new parameter `IMU_GYRO_FFT_EN` to start
 - add 75% overlap in buffer to increase FFT update rate
 - space out FFT calls (no more than 1 per cycle)
 - increase `IMU_GYRO_FFT_MIN` default
 - decrease main stack usage

 * HealthFlags: define bitfield using 1<<X

Co-authored-by: Matthias Grob <maetugr@gmail.com>

This is done to prevent yawing 180 degrees when switching
to hold mode with high velocity and the overshoot causing a 180°
yaw turn.

The yaw is unlocked on waypoint updates and the yaw
setpoint generation had to be put at the end because otherwise the
first yaw calculation is with the old waypoint and immediately
locks again.

 - skipping these sensor checks in HIL no longer makes sense as each
sensor has a normal publication (sensor_accel/gyro/etc) regardless of
simulation

after NuttX 9.1.0+ upgrade #15139

benefits:
- read & validate product name
- sensor configuration with the output we want (raw distance data)
- get signal quality

Protocol description: http://support.lightware.co.za/sf20/#/commands

Other Lightware sensors can easily be moved over to that as well.

This removes the exception handling of airship type vehicles when scaling actuators for the simulator

The enumeration changed from usbmodem1 to usbmodem01 and this tracks this OS-level naming change.

 - mavlink messages DEBUG/DEBUG_FLOAT_ARRAY/DEBUG_VECT/NAMED_VALUE_FLOAT move to separate stream headers and don't include if CONSTRAINED_FLASH
 - mavlink receiver DEBUG/DEBUG_FLOAT_ARRAY/DEBUG_VECT/NAMED_VALUE_FLOAT handling excluded if CONSTRAINED_FLASH
 - msg: skip debug_array.msg, debug_key_value.msg, debug_value.msg, debug_vect.msg if CONSTRAINED_FLASH

The battery migration interferes with the tests.

Avoid a GCS showing 2 battery indicators.
Alternatively we could also check the 'connected' flag, but this is more
explicit.