ARK Flow application on quadcopter

Matte_Lanni · January 2, 2022, 11:42am

Hi all, I’ve recently come up with a doubt about optical flow algorithms, especially the one used in PX4Flow modules, which is the same firmware flashed on the Ark Flow module (which I’m planning to use):
what if there is a “fixed object” in the field of view of the optical flow sensor?

In particular I’m wondering if I mount the sensor very close to the landing gear of my quadcopter, and a portion of the landing gear gets in the view of the sensor, will it negatively affect it’s functioning? (consider it would obscure a very limited portion of the sensor view).

Thank you in advance

ryanjAA · January 2, 2022, 11:06pm

@AlexKlimaj maybe good for you to chime in.

AlexKlimaj · January 2, 2022, 11:44pm

Hi Matte, just to clarify, the px4flow and the ARK Flow don’t use the same firmware. ARK Flow runs upstream PX4 as a cannode board config.

I can’t speak to the algorithm the PAW3902 uses internally for optical flow.

On my larger test quad seen in the videos, there is a good chance the landing gear is in view of the PAW3902.

AlexKlimaj · January 3, 2022, 7:30pm

Actually, on my larger test quad, the landing gear is not in view of the PAW3902.

Here is a 3D model with the FOV.

github.com

ARK-Electronics/ARK_Flow/blob/main/Hardware/Rev 2/ARK Flow Rev 2 3D Model With FOV.step

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Matte_Lanni · January 9, 2022, 11:25am

Hi, thank you very much for the reply, now I can understand a little better the difference between the two modules anyway I still wonder if in the case of the landing gear being in the view of the optical flow it could negatively affect the performances, is it possible to try it in a simulation?

AlexKlimaj · January 10, 2022, 8:30pm

Unfortunately there is no way to simulate the algorithm internal to the PAW3902. I will need to test it by putting something across the landing gear in the field of view of the sensor.

AlexKlimaj · January 12, 2022, 8:44pm

I just did a test with a ruler in the FOV.

I did a control without to verify position hold with optical flow only first and it flew great.

With the ruler in the FOV, the paw3902 outputs data with a reasonable quality metric, but the EKF didn’t like the data and rejected position hold.

So the answer to your question in no, the ARK Flow will not work with a fixed object in the field of view.

Matte_Lanni · January 15, 2022, 10:57am

Wow that’s amazing, thank you very much for running an actual test, I really appreciate that your help is very useful, I will now work around another solution. Thanks again!