Hello,
I am currently working on a UAV that can fly autonomously within a tree plantation.
We are facing significant issues with the GPS.
We are currently using two Here 4 GPS, using a Ublox Neo F9P chip. We are also using the Here 4 Base. We are currently using only the GPS and Beidou constellations to have a good update rate. In the GPS_DRV_OPTIONS, we have enabled L5.
We are unable to get a home fix. We have good satellite counts and good HDOP. But the course over ground keeps changing. It shows 3D Fix on Mission Planner, but we constantly get the message GPS Glitch or Compass Error. Sometimes AHRS waiting for home. The UAV is unable to fix its home location. I believe this is due to the high moisture content of the rubber trees in the plantation and the signals’ multipathing a lot.
Some of the solutions we have come up with are:
-
Switch to an ArduSimple RTK GPS simpleRTK3B Pro running the Septentrio Mosaic X5. This seems to have a significantly higher update rate and also shows support for Navic.
- Use a triple-band GNSS antenna.
- Add an SBG INS system as an external NAV system to the Ardupilot EKF, In case GPS glitches a bit, the INS can provide reliable data for a bit, not for long, though.
- Integrating some sort of Visual Odometry. We currently possess a ZED 2i Stereo Camera.
Are these all good enough solutions to implement to ensure I get a good 3D fix and can easily navigate in the plantation? Would the Visual Odometry work alongside the GPS in ensuring a position fix, or is it one or the other? I couldn’t find a suitable guide for integrating both at the same time, which is why I’m making this post. I cannot easily travel to the test site, so I need to make sure that the changes I make to my system are good enough. Thank you. Any input would be helpful.