Hi - this is a plea for help here… I have scoured the internet over and over looking for answers, but to no avail. I have used this site to get started: http://dev.px4.io/flow_lidar_setup.html Setup: Pixhawk with 3DR Optical Flow Camera connected over I2C I have GPS Off, LPE set. I see Optical F…

What distance sensor are you using? The sonar of the PX4FLOW or a separate range sensor? I would definitely recommend that you look at the data in flight with a telemetry module. You should look at the quality measurement in the flow message as well as the distance from your range sensor in DISTAN…

Thanks Nicolas for the reply! Much appreciated. Bunch of simple questions below… Range sensor is the SF11-C, which is reported to be supported in the latest PX4 builds. https://www.parallax.com/product/28054 So not using the Sonar, although I don’t know how to ‘disable’ it. Does the SF11 autom…

So not using the Sonar, although I don’t know how to ‘disable’ it. Does the SF11 automatically override it when I set SENS_EN_SF0X Set to 1? SF11 should take precedence over the sonar on the PX4FLOW module. You can easily test this by looking at the distance measurements in QGC and covering up on…

Excellent info! Glad I bought that SF11 then on a hunch. We shall look at the code, thanks for pointing me in the right area. In QGC, I am a little new to logging. The messages you refer to are in MAVLINK messages? I would like to know what the recommended Widget is to see these… Sorry for new…

The mavlink log messages are displayed in QGC under “vehicle messages”, which looks like a megaphone (or red exclamation point if there are critical messages) as shown here: https://donlakeflyer.gitbooks.io/qgroundcontrol-user-guide/content/QuickStart/QuickStart.html (section “connecting the drone”) …

Ok Nicolas - I have some work to do then. I will report back with the flow stats when in flight, using telemetry and QGC. Appreciate your help so far! Derek

Ok - so it works! I think the patterned carpet I tried today made the quality go up. Not sure. But with telemetry I can see the success. One issue I do have though is that the Lidar will come and go, even when stationary, and I see occasional messages: lidar fault, beta 157.08 lidar fault, bet…

[image] Strongbad71: lidar fault, beta I see it in source but not sure what it signifies, or if it impacts indoor positioning directly. https://pixhawk.ethz.ch/docs/lidar_8cpp_source.html // fault detection 98 float beta = (r.transpose() * (S_I * r))(0, 0); 99 100 if (bet…

That means that the measurement produced by the lidar is considered to be an outlier and is not fused into the estimator. You can observe the lidar measurements in the QGC Analyze widget, look for DISTANCE_SENSOR. If you are getting a lot of bad measurements from the lidar, your height above ground …

Pixhawk+PX4: Cannot get Optical Flow to work!

PX4 Autopilot

Strongbad71 September 19, 2016, 9:47am 11

I will have to correlate when I see these errors to what is actually physically happening at that moment.

Thanks Nicolas!

Experiencing large (10-100-1000+ meters) drift in local position with PX4FLOW

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Pixhawk+PX4: Cannot get Optical Flow to work!

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