We have just pushed a patch release - Copter-3.4.6. This is a very minor change on top of Copter-3.4.5 but fixes a nasty arithmetic exception that could occur if the WPNAV_LOIT_SPEED parameter was set to zero. Release Notes are here and the change is:
ensure WPNAV_LOIT_SPEED is non-zero to avoid divide-by-zero
In short, the vehicle would lose the ability to control it’s position in Loiter if the WPNAV_LOIT_SPEED parameter was set to zero which is luckily not something that people do much. If this happened, the pilot could only recover in manual flight modes light Stabilize.
Thank you very much to “darcopter” who reported the issue on this thread including logs.
Nice catch! I think you’re right, people actually keying “0” to the parameter is probably exceedingly rare if never. Other than maybe someone saying “I wonder what would happen if…”. BUT, what could be a risk is if someone uses the CH6 tuning knob to adjust the speed on the fly. Turn it down all the way and that would get ugly.
Pedals,
We actually don’t support changing the Loiter speed with the tuning knob, it’s the waypoint speed that can be changed… and luckily that one didn’t suffer from this problem.
Pedals,
You are absolutely right that it’s listed as an option. I will remove that. Looks like we did have the ability, removed it at some point but didn’t update the docs. I will fix the docs tomorrow, thanks! … or maybe I’ll add back the ability to tune it…
Thank you Randy for the fix! My pleasure to have made this very little contribution.
I’m still trying to understand what is it that caused WPNAV_LOIT_SPEED to get set to zero. Certainly not my intent.
I have been flying this quad for a while with no problems. But I had just played with 2 parameters prior to this particular flight. So it could have been me unintentionally touching WPNAV_LOIT_SPEED or maybe a bug in Mission Planner?
Does it make sense to contact the Mission Planner team and ask for a quick review?