Holybro PMW3901 Optical Flow not usable for non gps navigation

Hi all,

so I am currently using a CubeOrange and wanted to set it up for indoor navigation. Since I already had the Crazyflie running on ArduPilot I dicided to take its Rangefinder (VL53L1X) and something similair to its OpticalFLow Sensor (PWM3901). I ended up ordering this sensor from Holybro:

since I already got my frame from them. So I configured everything and set everything up according to the documentation and I could see results in the status bar in MP. But as soon as I switched the Parameter EK3_FLOW_USE = 1 (Navigation), I get the following errors in MP:

And what I tried I coudn´t resolve this issue. I also performed a short flight in stabilize mode as well as a calibration. Find the log files attached:

What is going on here? The Rangefinder seems to work properly (not throwing any errors). Tested this on multiple CubeOranges as well as with different sensors (I got multiple of them). The PD estimation of the KalmanFilter also seems to be weird (XKF1) with the IMUs and the Rangefinder performing normal.

How can I resolve this issues?

Thanks in advance :slight_smile: