GyrX is Smaller in Scale Compared to Flow Data


I have been trying to calibrate my Optical Flow sensor. It is a Matek 3901-L0X sensor.

During the calibration process, I noticed that the IMU GyrX data was larger in scale compared to FlowX and BodyX for the sensor. Nothing in Optical Flow Sensor Testing and Setup — Copter documentation is telling me how to fix this issue or that it ever was an issue. Here is a screenshot of what I am seeing:

Also, below are some relevant files including the log that generates the image you see above:
Log: Microsoft OneDrive - Access files anywhere. Create docs with free Office Online.
Config Params:
config_params_2022-03-07.param (16.5 KB)

Let me know if you need additional information!

I think you have to change the FLOW_FYSCALER and FLOW_FXSCALER to -800, I read this in another forum post for the sensor but couldn’t find it again. I’m also using the same sensor and I’m having issues with it giving readings. It only works when I reboot the FC randomly. What firmware version are you using?

Edit: here’s the link to the post: Optical Flow - Problems

Thanks for the reply! Yeah I thought the FX/FY Scaler was used for FlowX larger than BodyX for the sensor but I dont remember, I will try when I get home today.
I can point you to another topic I created about this sensor, hopefully it helps your issue a little:Matek 3901-L0X Setup Help - No Data and Bad OptFlow Health Message - #8 by MaxBuzz

So after applying -800 for X and -775 for Y, I get pretty close:

The difference is just from the offset in the graph axis, I believe.
For the Y, it matches more:

Thank you! It worked!!

That’s great to hear, I read in your original post that you were using 4.0.3, is this the version you’re still using? I switched to 4.0.7 and the sensor does not display values at all anymore.

I actually ended up upgrading to 4.1.5 as Ardupilot didn’t support the Matek sensor just yet at 4.0.X. I think that was an additional underlying issue that I fixed while getting to the root of the problem. Try it and let me know what happens!

Yea no wonder 4.0.7 and 4.0.3 didn’t work at all. 4.1.5 and 4.1.0 are giving me that issue, but 4.1.0 has a higher chance of working on reboot for me. Are you using the original sensor board or the new revision with the different MCU due to chip shortage?

That is strange, I am using this one:

Did you get the drone to arm in loiter/guided mode? It keeps saying need position estimate for me.

Edit: also, is there a film over the sensor lens? I think there is for mine but I’m not sure and don’t want to damage it.

I haven’t checked to see if there was a film on mine. It looks good based on your plots so I would say leave it.

Also you need to right click on the map and set home to EKF Home point and that should allow you arm it.

It’s all laid out here pretty nicely !

I did do the homing part but it still gives me the error, any ideas? What parameters did you change?

Maybe try and run a diff between your config params and the config params I attached at the beginning of the forum?? If you have Ubuntu or some Linux app on your computer just run "diff "