Currently it seems like only two altitudes the quad will start RTL at are the current altitude, or RTL_ALT (whichever is lower). And RTL_ALT is limited to about 80m.
Is it possible to have the initial RTL altitude be the current altitude + some buffer altitude? This is for cases where you may inadvertently descend or fly behind something that triggers a failsafe, but you know that there’s no altitude limit… like when you’re going up/down a mountain and and you fall on the wrong side of a ridge that cuts direct LOS.
Where did you see it?
This parameter is stored as
int32 in centimeters and I couldn’t find a restriction to that in the firmware.
There is a parameter for following the terrain during RTL.
Just from the param description on the website. I suspected there was no actual limit but I admit I haven’t tested it out yet.
I’d like to try the terrain follow at some point, but having to rely on one additional feature for RTL is just one more thing that could go wrong.
I don’t think
some buffer altitude approach is a safe solution for your case.
That buffer will not be sufficient enough or will be too high, based on your location of the terrain.
If you don’t want to rely on terrain-following, setting the RTL_ALT higher than the tip of the mountain is the safest approach.
The optimum solution is using the terrain-following during RTL.
You’re right that the best approach is to set the peak altitude and fly over it.
I may not carry a computer with me to be able to set RTL_ALT on a whim and I’d prefer not to have to leave an arbitrarily high RTL_ALT configured (for the reason that it may be too high). So either an option have the quad fly back to max altitude seen or point of failsafe + value could be a better alternative to me.
My use case would be flying in a manner that just a small amount elevation increase would be sufficient, like if I accidentally dip below the ridge as I’m flying along it. I’m not flying sideways behind large objects whereby the only way to recover is SmartRTL or fly all the way above the object.
Barring this… I guess my alternative is to leave FS on SmartRTL and for video loss, I muscle memory into loiter and lift the quad in hopes that I get video back?
Set RTL_CLIMB_MIN (centimeters) to how much you want to add to current altitude when RTL is triggered.
I must have been thrown off by the max range listed for that param and missed it did what I wanted… Thanks so much!