I had an issue in SITL where my plane would round the last WP staring
its landing approach and immediately limit the roll to 5degress even
before the plane had finished turning the corner so it would go WAY
off course. For a high value of LAND_FLARE_SEC (mine was 5) the math
works out the plane has landed if
height <= sink_rate * land_flare_sec
During the banking of the last corner the plane started to decend and
quickly set itself up for a 6.1m/s sink rate which is normal. It was
at 30 meters altitude. As you can see at this point the math thinks
the plane has landed so limits the roll. The solution was to ensure
the plane had covered at least 50% of the distance toward the final
waypoint before allowing a flare to happen. Note that LAND_FLARE_SEC
above 2 is considered very high and this normally wouldn't occur.
Reverse thrust for controlled landings, even with much steeper approach slopes. This is achieved by allowing throttle demand to go negative to maintain a target airspeed. A Pre-Flare stage was added, triggered by an altitude, to allow for a slower airspeed just before land. That lower airspeed can be near stall.
new params LAND_PF_ALT, LAND_PF_SEC, LAND_PF_ARSPD, USE_REV_THRUST
The PSTR is already define as a NOP for all supported platforms. It's
only needed for AVR so here we remove all the uses throughout the
codebase.
This was automated with a simple python script so it also converts
places which spans to multiple lines, removing the matching parentheses.
AVR-specific places were not changed.
we only accept a lidar if it changes by 5% of its full range, and we
reject a lidar again if the correction between barometric and lidar
range changes by more than 30m
This allows us to cope with faulty lidars which may give a constant
reading
when aborting a landing via mode change, check if NAV_CONTINUE_AND_CHANGE_ALT is after LAND. If so, go ahead and execute it. Else, normal behavior or check do_land_start else decrement mission index
- enabled via new param LAND_ABORT_THR default is 0 (disabled)
- Triggered via 95% throttle during landing, a landing abort will take place.
- This copies all takeoff params for right now, we can make this better later if needed
- added mission item command to NAV_LAND which is the abort takeoff altitude. If 0 then use last takeoff if available, else use 30m
- hold heading, just like takeoff, until altitude is reached
- pitch is constrained to takeoff pitch, or else 10deg if not available
- After abort altitude is reached, the normal landing restart happens (DO_LAND_START or decrement mission)
- restart landing by jumping to DO_LAND_START or decrement mission on mode change
If someone mistakenly puts all 0's in their LAND command then
total_distance will be calculated as 0 and cause a divide by 0 error
below thus crashing ArduPilot. Lets avoid that.
Tom Pittenger
Grant Morphett
Luis Vale Gonçalves
lvale
Lucas De Marchi
Andrew Tridgell
squilter
Michael Day
Andrew Tridgell