Sudden loss of control, vibrations?


I have a windsurfing board powered by two BlueRobotics T100 thrusters, controlled by a Pixhawk running Rover 2.50 with skid steering enabled.

Now I’ve experienced sudden loss of control during several auto missions. Normally it runs perfect for some time, but then suddenly it will deviate heavily from it’s track to the next waypoint.

I don’t suspect bad hardware nor issue with the Rover code. I’m quite confident that it’s something with my setup (e.g. underpowered, mag field) or external forces that are changing the conditions (wind, waves etc).

My own theory after analysing the tlog from my latest mission, is simply that the sea is getting rougher and somehow affect my ship to the point that control is lost.

For anyone interested in helping out with analysis, the tlog is provided on the link below: … .tlog?dl=0

Unfortunately this tlog starts some 19 hours before the mission starts. Sorry for that.

The loss of control appear at 10:43:30. Before that, performance is flawless (in my opinion :slight_smile: I regain some control at a later point in time but it’s quite bad.

My list of suspects:

  1. Vibrations due to higher wind and waves. But how sensitive is the rover code to vibrations really? the RAW IMU x,y,z acc shows quite significant increase at around 10:43:30. I know wind was also picking up around then.
  2. Lower voltage after a while that reduce the max RPM of the thrusters, giving less control. Maybe a combination with 1.
  3. Downwind travel, where the speed through water is very slow while airspeed/gps speed is up to target speed. I guess this will make the craft unstable. We’re talking a max speed of 1.3-1.5m/s here. So very slow indeed.

Any help is appreciated!


A dataflash log would be better for analysis then the tlog if you could provide it?

Thanks, Grant.