instead of the derivative of the vertical position which is
not the same value when using the ekf2 estimation.
Using the position derivative resulted in delayed landing because
the value for some reason often bumped over the theshold before
slowly converging towards zero while the velocity was within expected
accuary in all these cases.
PositionControl: update comment about the order of thrust and position
mc_pos_control: reset setpoints to NAN if required
MulticopterLandDetector: consider to be landed if vehicle is not armed
mc_pos_control: initialize landing struct with landed
mc-pos-ctrl: adjust thrust-setpoint and yaw during ground-contact/maybe-landed without capturing
that information within vehicle-local-position-setpoint topic because that information
does not belong to user intention
PositionControl: set local position/velocity setpoint to NAN if not used in the control pipeline
mc-pos-ctrl: Fill vehicle_local_position_setpoint_s structure as follow:
The message contains setpoints where each type of setpoint is either the input to the PositionController
or was generated by the PositionController and therefore corresponds to the PositioControl internal states (states that were generated by P-PID).
Example:
If the desired setpoint is position-setpoint, _local_pos_sp will contain
position-, velocity- and thrust-setpoint where the velocity- and thrust-setpoint were generated by the PositionControlller.
If the desired setpoint has a velocity-setpoint only, then _local_pos_sp will contain valid velocity- and thrust-setpoint, but the position-setpoint
will remain NAN. Given that the PositionController cannot generate a position-setpoint, this type of setpoint is always equal to the input to the
PositionController.
mc_pos_control: switch to designated initializer for landed
It's less error prone because it produces an error on every discrepancy.
- no airframe changes the default
- it does not make much sense to be able to configure the 0.1 threshold
but the 0.3 threshold for ground contact detection cannot be configured.
Using the vertical derivative estimate prevents vertical velocity offsets caused by estimation vertical velocity errors preventing the vehicle disarming.
Before that, different modules (ekf2, commander & land detector) changed
params upon different events:
- ekf2 & commander set params after disarm
- land detector set params on land detected
If the 2 events were several 100ms appart, it led to 2 param saves, and
the latter param set could have been blocked by an ongoing save. And if
the land detector was blocked, it could lead to mag timeouts.
This patch makes all modules use the same event, thus only a single param
save will happen.
If we want to have guarantees to never block, we should introduce a
param_try_set() API method.
This commit is an attempt to fix a race condition happening on takeoff
between the land detector and the multicopter position controller.
Previously, an auto-takeoff leads to the following events:
1. A takeoff setpoint is given.
2. The thrust setpoint spikes because we don't enter smooth takeoff yet.
3. The land detector detects a takeoff because of the high thrust.
4. The position controller sees the landed state transition and
initiates the smooth takeoff. Thrust goes back down.
5. Depending on control gains the takeoff is successful or fails
if the smoothing takes too long which causes thrust to be too low, so
the land detector detects land again.
The two obvious problems with this are:
- The intermittent spike.
- The failed takeoff because of the smoothing leads to a delay..
With this change, the logic for a takeoff detection is moved from the
land detector to the position controller.
The events are now:
1. A takeoff setpoint is given.
2. The position controller detects the takeoff setpoint and initiates
the smooth takeoff.
3. As thrust ramps up, the land detector detects the take off.
In the same way, we now detect the intent to takeoff in manual,
altitude, control, position control in the position controller instead
of in the land detector.
because in altitude mode we have a baro available and can therefore check vertical movement
we can not check horizontal movement but I consider the checks for landing still pretty safe
unlike in manual mode we are not allowed to disarm before land detection in altitude mode
Even for well calibrated RC sticks 5% stick movement is a too small margin for the end user that might not land because of this.
15% is still clearly restricting the stick far down.
Ground detect: pilot want down or we are on minimum thrust by auto land but no vertical movement
-> Controller should relax x,y corrections and even ramp down desired thrust
Landed: All other conditions are eventually met
- constructor initalization fix
- set trigger time for ground contact hysteresis
- updated ground_contact_state logic
MulticopterLandDetector:
- added hysteresis for ground_contact
VtolLandDetector:
- get_ground_contact_state function that return the one form MultcopterLandDetector
FixedWingLandDetector:
- get_ground_contact_state with a return false: requires implementation
This allows to detect ground contact before concluding the system is landed. This allows to disable some parts of the horizontal control system and only control the vertical position to avoid tipping over.
;
Matthias Grob