I thought the issue with VTOL platforms going to RTL on battery failsafe was fixed in the latest firmware version but sadly, it doesn’t seem to be and almost cost me the platform. I am flying a very modified Nimbus setup with the CUBE and latest stable firmware (3.9.8). I was flying an automatic mission (from start to finish with VTOL_LAND as the last command), the battery was at 22.3V right before the transition to copter mode and then due to the high amp draw, got sucked down to below 21.7V (where I have my Low Battery Failsafe set). At approximately 4 meters from the ground during the landing phase, the platform decided to initiate RTL and proceeded to transition to Fixed Wing and fly home (actually, I have RTL_AUTOLAND setup so that it repeats the landing approach). I switched out of Auto and back into it to over-ride the RTL and it proceeded to return to the landing zone where I took over manual control and landed in Q_LOITER.
This is VERY DANGEROUS!!! I was a few seconds away from watching the platform fly into a power-line and tree when I grabbed the remote and took over control. Please please please can we do something about this? The logs for this flight can be found here: https://we.tl/t-2JTR46H80Z
If someone can get back to me on this asap that would be fantastic. This issue causes major concerns for operations where you do not want to land where you took off from (ie, home) and removes the viability of low battery failsafe as with it enabled, this issue happens, and with is disabled, well, you dont have that security.
VTOL_LAND is a mission command within auto mode, so it is in auto mode rather than land mode. It looks like we would need a few changes to the flight_stage code so that a auto mode landing in vtol would stop a RTL
I have just made and update with a very simple solution in the issue that I reported on github (see my last post in that topic). Can you please take a look and see what you think? If this was implemented, then all but the most extreme cases will be able to operate safely.
Hi Guys, I am worried about this Fail safe problem, but fortunately I never got this problem during my Vtol flight auto mission. So, before we have permanent solution, what do you think “temporary” solution to avoid this FS problem??
In think I will not set low batt. FS (since this issue may happen anytime). Also I wish can set the delay disarm (after landing) to Zeo (So ardupilot will Disarm immediately after landing), but unfortunately can not do that now. Based on current firmware, the minimum value is 1 second. I agree that this FS problem is very very Serious issue to be solved as soon as possible. I suggest The logic as follows:
1). FS (and RTL) can not be triggered during landing process.
2). Landing mode can override RTL or FS mode.
3). Disarm delay value (after landing) can be set to zero (autopilot disarmed immediately after landing).
I hope developers consider Safety as number 1 priority to be solved.