OPTICAL FLOW 3901-L0X Problem. One axis does not show flow movement


Me and my team are working on a project in which we are developing four 7 inch drones which use the same components and firmware (ardupilot 4.4.0). We are using the OPTICAL FLOW 3901-L0X in all of them which have been working ok.

However, recently we acquired more optical flows from matek which should work fine but this is not what was observed. Despite using the same parameters as before we can not get accurate flow movement from the longitudinal axis of the optical flow board.

I would like to know if anyone encoutered this problem aswell with new matek opflow boards.

Here are some ardupilot logs with different values for the ​​​FLOW_FYSCALER parameter in which you can see there is no considerable difference in the readings:

FLOW_FYSCALER -800: 1.2 MB file on MEGA

FLOW_FYSCALER 0: 1.05 MB file on MEGA

FLOW_FYSCALER 800: https://mega.nz/file/oMIGBZxb#Stis5vYwG7bc-mvSGehleDJ23pwXyqKQ21vzjXnBGo0

Thanks in advance

Have you reported the issue to Matek? you should.

Yes I already sent them an email but didn´t get a reply yet. However, I also decided to share the information here to see if anyone as encountered the same problem


Despite the log showing no flow movement in the x axis while logging while disarmed, I tried flying the drone in loiter without gps and everything works fine. The drone keeps position and brakes when I let go of the sticks. Very strange. Also the log of that flight shows flow movement in the x axis… :thinking::thinking:

Log: 6.84 MB file on MEGA

I believe I’m experiencing a similar issue. I’ve tested two 3901 L0X modules, and both have experienced very poor x axis flow readings, while the y is perfect.

I then tested outside, and the OF was spitting out perfect data.

This is my first experience with these OF modules, but they seem to be very sensitive to poor lighting. Unfortunately, the LIDAR module has the opposite problem- it seems bad readings the better the lighting gets. Are you using a different lidar module?
POOR_X_GOOD_Y_3901_L0X.bin (465.6 KB)

I’ve attached my log as a comparison.

Yes I am using a TFmini lidar.

The standard lidar that is available on these boards (L0X) is not good for outdoors use. The sun light decreases its maximum range as any other lidar. However the maximum range for indoors use of this lidar is already pretty low