Cross Track Tether: This functions like a rolling geo fence. If the rover ever exceeds the Cross Track threshold (mine is set for 2 meters) it will stop the blade, and switch the mode to HOLD. If I deem everything is OK, I can switch the mower to MANUAL and that will reset the Cross Track Tether, then switching the mode to AUTO will restart the mission. Cross Track error is the amount of distance from the intended GPS course to the next waypoint.
My mower has had two different failures (so far) that have caused it to veer off course: loss of RTK fix and a mechanical malfunction. I was impressed with Yuri_Rage’s minFIX program and it motivated me to write my own version for my electric mower. That took care of the RTK loss however did not address a (hopefully rare) mechanical malfunction. Even worse, because it would still have a RTK fix, the mower blade would be spinning as it ventured off track.
My mower is a skid steer type and the right-side drive malfunctioned and was free spinning. The left-side was still functioning and the mower was trying to turn back, but instead the mower was driving off mostly in a straight line due to the right side not assisting with the turn. I stopped it just as it hit a stone bench and the only damage was a 3D printed bumper stop switch holder. (The bumper switch engaged a bit too late). This got me thinking about how to know when the mower is way off course due to any reason, chain derail, breaking or any other thing that could happen. That got me looking into cross-track errors and a cross-track failsafe. I found others who were also wondering about this, however, I never found a working example. Here is my version for my mower rover that also has the RTK requirement in case anybody wants to play with it. The loss of RTK will stop the mower and blade and then restart everything automatically when it reacquires RTK. The stoppage due to the mower exceeding the Cross Track Tether threshold, will need a manual reset (mode change) and then toggling the relays manually to restart the blade.
gomowRTKXT.lua (6.8 KB)