navigator: let vtol descend in fixed wing mode before transitioning #10404
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I don't recall the full discussion, but I believe the only reason this wasn't already done was potential safety concerns and the general awkwardness of transitioning from a FW loiter rather than towards the actual home. That being said, I'm fine with this PR if we make sure the default VTOL descend altitude is safe. |
src/modules/navigator/rtl.cpp
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| if (_param_land_delay.get() < -DELAY_SIGMA || _param_land_delay.get() > DELAY_SIGMA) { | ||
| // if we are a VTOL and in fixed wing mode then we should now transition to rotary wing mode | ||
| if (_navigator->get_vstatus()->is_vtol && !_navigator->get_vstatus()->is_rotary_wing) { | ||
| _rtl_state = RTL_STATE_TRANSITION_TO_MC; |
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Can you reorder the switch so it follows the intended order of execution.
RTL_STATE_RETURN -> RTL_STATE_DESCEND -> RTL_STATE_TRANSITION_TO_MC -> ...
- previously during an RTL the transition back to rotary wing mode was triggered when the plane reached the home position at the RTL height. It makes more sense to do the descent phase in fw mode in order to save energy and for stability reasons. The plane will now fly down to the descend altitude in fixed wing mode and then do the transition to rotary wing mode. Signed-off-by: Roman <bapstroman@gmail.com>
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We could, but isnt that making it needlessly complex? |
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That could make sense, but I'd still be worried about general transition safety. How far does a transition tangent to a FW loiter around home take you away from the home position? What about wind direction? It basically means at transition altitude you'd need to ensure a safe radius of several hundred meters around home (the worst case). That's fine if you're operating from a field. The other (minor) thing to check is the back transition logic from loiter. The vtol controller will abruptly and simultaneously force the vehicle level (roll and pitch to 0 or offsets) while cutting the throttle (all with TECS disabled). In my mind this quickly turns into the same situation as FW where a planned landing sequence at the end of the mission (marked with DO_LAND_START) should be required and used for RTL in most real world situations. |
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This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions. |
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Is there something wrong with this PR? @RomanBapst |
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This issue has been automatically marked as stale because it has not had recent activity. Thank you for your contributions. |
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Will be implemented in a nicer way in #14728 |
Previously during an RTL the transition back to rotary wing mode was
triggered when the plane reached the home position at the RTL height.
It makes more sense to do the descent phase in fw mode in order to save
energy and for stability reasons. Note also that the RTL height could potentially be quite high and so we really should avoid descending in rotary wing mode.
The plane will now fly down to the descend altitude in fixed wing mode and
then do the transition to rotary wing mode.
Currently the descend altitude is quite low (10 m) by default which is probably too low for vtol transitions.
So we should handle that somehow before merging this.
@dagar @sanderux FYI
Signed-off-by: Roman bapstroman@gmail.com