land_detector: quick workaround for MC NAN setpoints #15426
Conversation
dagar
force-pushed
the
pr-land_detector_finite_quickfix
branch
from
8395e3d to
2895168
Compare
|
|
||
| if (_vehicle_control_mode.flag_control_climb_rate_enabled && vz_valid) { | ||
| // setpoints can briefly be NAN to signal resets, TODO: fix in multicopter position controller | ||
| if (PX4_ISFINITE(_vehicle_local_position_setpoint.vz)) { |
There was a problem hiding this comment.
This means in every case where there's no vertical velocity setpoint the _in_descend state just stays how it was. The only cases that come to my mind where no vertical velocity setpoint is set (intentionally) are: the thrust cut when ground is detected (that's the constelation that leads to the bug you found) and the in failsafe descend when there's no RC and the vehicle looses the vertical velocity estimate.
What about we capture the case where there's no vertical velocity setpoint and in that case compare vertical acceleration. E.g. the thrust cut is a huge downwards acceleration to enable the land detector to detect maybe landed and landed. And with that huge downwards acceleration you expect no freefall.
There was a problem hiding this comment.
The acceleration condition sounds good, I'm not sure what that wasn't already a factor. My only immediate concern is the current time scale of the ground contact and its hysteresis.
There was a problem hiding this comment.
In flag_control_climb_rate_enabled (and vz_valid) if the vz setpoint is NAN we could just set _in_descend to true.
There was a problem hiding this comment.
in failsafe descend when there's no RC and the vehicle looses the vertical velocity estimate.
Actually, this one isn't going to matter because ground_contact is only used by maybe_landed if vz and z estimates are valid.
|
Going back to the larger PR. #15083 |
This is a quick fix for one of the issues found in the process of fixing other MC land detector issues.
When the multicopter position controller sees
ground_contactthe setpoint reset (NANs) is briefly published onvehicle_local_position_setpoint. This can force the multicopter land detector_in_descendstate immediately back to false which interrupts ground_contact if not currently in low thrust.https://github.com/PX4/Firmware/blob/7354e3989335dfb38cc41216182f48fe84d165c7/src/modules/mc_pos_control/mc_pos_control_main.cpp#L644-L654