PX4Flow disturbed by IR pulses of MOCAP


I cannot use PX4Flow together with a motion tracking system (I use Optitrack).

By looking at the images sent via USB when the PX4Flow is pointed directly towards a mocap camera, it is clear that the PX4Flow sees the IR leds (850nm) flashing at 100Hz. When pointed at the ground, the brightness of the image jumps randomly.

When flying a quadcopter in position control using PX4Flow as main sensor, the position is held stable (~10cm oscillations) when the mocap LEDs are turned off. However large drift occurs (~5m drift) when the LEDs are turned on.

I did not expect to have this problem as the PX4Flow’s lenses are described as

16 mm M12 lens (IR block filter)

Is it common to all PX4Flows on the market, or did I buy a bad copy?

Did others have the same issue? If yes, did you solve it by adding another IR filter to the lens?


@jlecoeur I am also observing a similar problem. I have an optitrack mocap system. I observe a lot of drift in position hold mode. If I switch the mocap system off, the position holds improves.

I still need to use mocap for ground truth though. So, I’m not sure how to go about this problem. Have you found a solution to this issue?


On older optitrack cameras (like the S250) you can set continuous LED lighting instead of stromboscipic lighting. With this the PX4Flow is not disturbed.

With newer cameras (like Prime 13 and 17) you cannot do that. The best solution is placing active markers on the drone, you can then disable camera LEDs. You can either build your own active markers using IR LEDs, or buy a set from optitrack.

Thanks @jlecoeur. I am working with the Prime 17 cameras. Is there a tutorial on building custom IR markers?