Obtaining underwater motion paths question

How can I use the QGC log file to calculate the path of Blue ROV2 running in the water?I tried looking for this variable in the log but couldn’t find it.

Hi @suitangxiaoyi,

If your vehicle has a positioning estimate then that should be available in QGC’s .tlog telemetry files in the GLOBAL_POSITION_INT messages. If you’re using QGC to download .bin log files off the flight controller I believe the relevant onboard (autopilot) message is POS, but the GPS and VISP messages might also be useful if you want to see the data being provided by your GPS or DVL.

If your vehicle doesn’t have a positioning estimate then the log file will not include the path, because it doesn’t know where it is or where it’s gone. You could try to calculate a relative path (from the starting point of the dive) by correcting the accelerometer values for attitude and doubly integrating, but that would only give you a rough shape of the path (without accurate distances), because the IMU sensor errors are too significant to be used for position estimation without some form of external correction.

Thanks for your help.

1 Like