PX4FLOW project restart

Since APM Copter3.3 start to support Optical Flow LOITER, my PX4FLOW project can be restarted

Yesterday, I installed APM Copter3.3rc8 to Pixhawk. Since it is a beta version, my QAV500 became a testing drone that can’t do long flight anymore in order to try the PX4FLOW LOITER earlier.

I followed the document to install the FA4FLOW.


I found there is a place under QAV500 bottom that mounts PX4FLOW easily.

PX4FLOW under QAV500
PX4FLOW under QAV500

I rotated the PX4Flow 180 angle, because of my I2C cable too short. x pointed to back, y pointed to left. I have to change the “FLOW_ORIENT_YAW” setting to 18000. ( If you not need to rotate the PX4Flow, just follow the document. No need to change the setting.)




You can’t sure the focusing of factory setup that is correct, so you have to adjust it. I use APM Planner, there is not interface to display PX4Flow visual video. Then I changed to use QGroundControl. You may check here for how to connect PX4Flow to QGroundControl. When you can see the video output, you can adjust the focus to 2-3m.


Flow Sensor Calibration

I followed the document to calibrate. The result is fine. Open the log file and got the chart below:

FX4Flow Flow Sensor Calibration log flow_y

OF.floxY vs OF.bodyY

FX4Flow Flow Sensor Calibration log flow_x
OF.floxX vs OF.bodyX

Then I did same test indoor, the result was much poorer, chart below:

FX4Flow Flow Sensor Calibration (Indoor)

When I do the Range Sensor Check, the document said that EKF5.meaRng will show the distance data, but my log is 0. I don’t know what is wrong.。I didn’t install range finder, may be this reason. However I would not buy a Pulsed Light unit for this. So, leave it then go to flight.


Compare to GPS, the Optical Flow is not show stable. It move 2-3M. I did the test outdoor. If I want it can stable indoor, it can’t move more then 0.5m. I don’t know can I improve it by calibration, or wait program upgrade.

Welcome your comments