@rmackay9 recently reached out to me after I posted a YouTube video of a zero turn mower using GPS yaw with Rover 4.1.0, a Cube Orange, and ArduSimple SimpleRTK2B F9P boards (fixed base, moving base, and rover). This thread seems an appropriate continuation of that brief comment exchange. I’m not sure I should post the video link here, since I don’t want to seem as if I’m just shilling for video views.
Here’s what I’ve learned after many hours of experimentation with parameters and settings:
I spent HOURS rebooting and tweaking parameters with Rover 4.0.0 and never achieved any real measure of success with GPS yaw. Rover 4.1.0-dev as of July 2020 seems to have improved things quite a bit. I did not dig into the code changes to determine why, but I cannot recommend GPS yaw under the 4.0.0 stable release based on my observations. The 4.1.0-dev branch works great for me at present.
The moving base and rover F9Ps must be connected directly to one another via their UART2 ports (what seems to be called “piggybacking” above), with GPS_DRV_OPTIONS=1 set. Attempting passthrough RTK from one to the other through the Pixhawk always fails for me.
While disabling GPS_AUTO_CONFIG makes for a faster initialization sequence, EKF3 never sees the config data it wants, and the sequence hangs, as described above. I always keep this enabled.
GPS_RATE_MS for both GPSs needs to be 100ms. Anything faster is glitchy, and anything slower results in bad GPS signal warnings (at least on the Cube Orange as well as an older fmuv3 board that I used until somewhat recently).
I have yet to achieve a solution to repeated nuisance warnings of “Bad Compass Health” when disabling all compasses. I always keep the internal compass enabled, which does seem to help with occasional GPS yaw failures when satellites drop from view or other brief (and as yet unexplained) errors occur with GPS yaw. I rarely see more than a fraction of a second of 65,535 on GPS2_RAW with my current setup, but it does occasionally/momentarily fail to achieve a solution.
@rmackay9 - I sent you the log file you requested via email, but perhaps it went to your junk mail. I’d rather not post full log files to the public forum in the interest of privacy, but I’m willing to share as much info as I can otherwise.