Optical Flow Sensor Fusion

RizHass · March 24, 2025, 5:26pm

I successfully integrated MTF-02P optical sensor in my quadcopter using a switch to use both GPS and non-GPS based EKF fusion as described in the document (MTF-02P - Optical&Range Sensor - MicoAir Tech).
But my question is more basic. How do I know when switching between the two options if one or the other is working?
On the Yaapu screen I didn’t get any messages to confirm which sensor is being used (Optical flow or GPS)?
https://drive.google.com/file/d/1dtFKHW1YLFqmX_3QxJU8jusE5hMntyyZ/view?usp=drivesdk

Allister · March 24, 2025, 5:52pm

There’s Lua scripts that will do that, but I haven’t been able to get them working with my MTF-01P. The sensor works great and just playing around with it I know it’s working (Note, they don’t work well over fresh snow on a bright sunny day).

If you’re in the Optical Flow/Range finder mode you will get Dead Reckoning warnings if you exceed the limits of the sensor.

RizHass · March 25, 2025, 5:57pm

It would be nice to have a message on the MP to acknowledge that which EK3 is in use. E.g. “EK3_SRC1 enabled (GPS)” or "EK3_SRC2 enabled (Opt_flow)"
At the moment all I get is relay6 low, medium, and high.

Can this messaging be added in the next build?

acoolguy · April 17, 2025, 1:06am

Is there an option to have the flight controller dynamically switch EKF sources instead of needing to be manually toggled?

I want to use optical flow whenever possible but use the GPS as well instead of it being a binary thing where it’s one or the other. Is that a thing? Can I do that?

Allister · April 17, 2025, 4:43am

Yes, If you’re running an H7 controller then Lua scripts can do that for you.

Here’s one example.

github.com/ArduPilot/ardupilot

libraries/AP_Scripting/examples/ahrs-source-gps-optflow.lua

Copter-4.5

-- switches between AHRS/EKF sources based on the pilot's source selection switch or using an automatic source selection algorithm
-- this script is intended to help vehicles automatically switch between GPS and optical flow
--
-- configure a forward or downward facing lidar with a range of at least 5m
-- setup RCx_OPTION = 90 (EKF Pos Source) to select the source (low=GPS, middle=opticalflow, high=Not Used)
-- setup RCx_OPTION = 300 (Scripting1).  When this switch is pulled high, the source will be automatically selected
-- SRC_ENABLE = 1 (enable scripting)
-- setup EK3_SRCn_ parameters so that GPS is the primary source, opticalflow is secondary.
--     EK3_SRC1_POSXY = 3 (GPS)
--     EK3_SRC1_VELXY = 3 (GPS)
--     EK3_SRC1_VELZ  = 3 (GPS)
--     EK3_SRC1_POSZ  = 1 (Baro)
--     EK3_SRC1_YAW   = 1 (Compass)
--     EK3_SRC2_POSXY = 0 (None)
--     EK3_SRC2_VELXY = 5 (OpticalFlow)
--     EK3_SRC2_VELZ  = 0 (None)
--     EK3_SRC2_POSZ  = 1 (Baro)
--     EK3_SRC2_YAW   = 1 (Compass)
--     EK3_SRC_OPTIONS    = 0 (Do not fuse all velocities)
--

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I commented earlier that I couldn’t get it to work, but that was my fault. I had the wrong script library in Github selected so I was getting script bindings that didn’t work in the version of Copter I was running.

acoolguy · April 17, 2025, 6:04am

Dude that’s freaking awesome!

I’m going to try that right now.