Getting reliable heading/yaw for a big metal vehicle?

ArduRover Rover 4.1
61

The RTCM3 path is like this:

  • Fixed base RTCM3 → Moving base (corrects moving base position)
  • Moving base RTCM3 → Rover (corrects rover position)

So, it is entirely possible for the rover GPS to have an RTK fixed state even when the fixed base is not operating. Again, you DO NOT need a fixed base for GPS yaw to work, and the rover fix type is only dependent on its position correction RELATIVE to the moving base.

If you are still using mismatched antenna types, that may also exacerbate the difference in position accuracy and fix type.

The firmware is mature enough at this point that you should not expect any observable difference between using autopilot passthrough RTCM3 vs direct a UART2 connection. In theory, a direct UART2 connection between the modules (GPS_DRV_OPTIONS=1) should be slightly more reliable and is probably preferable to relieve some burden from the autopilot, but in practice, there is little to no difference in results.

62

Ah, sorry, by base I meant the moving base. My system definitely can get a rover RTK fix and use GPS yaw regardless of whether the moving base is receiving anything from the fixed base. The rover fix is just isn’t perfectly consistent (in both cases). The antennas are now identical, so that shouldn’t be it.

But despite the occasional GPS yaw dropouts, the compass/EKF fallback works really well. I managed to find a place to drive around slowly under tree cover and the yaw was spot on the whole time. It performs as well as I need it to, so at this point I’m just curious about optimizing it.

63

GSF fallback should work reasonably well even if you disable the compass (which is what I do for anything with GPS yaw).

1 Like
64

Reading through this thread to get a better understanding of GPS Yaw and still feel abit confused.
If this should be moved to another thread/topic, please inform me.

I have 2 x Drotek Sirius F9P Rovers and 1 x Drotek Sirius RTK Base.
The Rovers are connected to GPS1 & GPS2.
RTK Base connected via usb to Mission Planner.
After a successful Survey In, HUD shows GPS: RTKFixed and GPS2: 3D FIX.
The Blue Marker on Map states Moving Base.
The Rover on the map is moving around(slightly) 50cm here and there.
Rovers are placed 25cm left and right respectively of Cube Orange.
I have set GPS_POS1_Y - 0.25 and GOS_POS2_Y 0.25.

Are all 3 gps units providing gps yaw, or just the 2 rovers?
Blue mark on map(rtk base) showing Moving Base is confusing to me.
My question now, what happens when SiK V3 radios are too far apart…will RTK corrections stop working?

How can I overcome this?
Should also mention I am using Siyi MK15 radio system.