The function `mission_item_to_position_setpoint()` is called in
`FollowTarget::update_position_sp()`. The nav_cmd is a
NAV_CMD_DO_FOLLOW_REPOSITION as set earlier in `set_follow_target_item`.
Since `mission_item_to_position_setpointi` returns early because the item
presumably contains no position, the lat/lon of the mission_item are
not copied over to the position_setpoint and therefore the vehicle will
never move in follow me position mode.
When checking a mission, the takeoff altitude is being checked
against the waypoint acceptance radius to ensure the MAV being
clear from ground before heading to the next waypoint.
However, until now the _horizontal_ acceptance radius was being
used, instead of the altitude reference value.
Targets PX4/Firmware/#7379
The TECS controller belongs really into the ECL (estimation & control library) where we have collected a number of vehicle control systems. It is being replaced by a new implementation of the algorithm, contributed by Paul Riseborough.
Instead of just checking whether the first waypoint is too far away from
home it makes sense to also check between waypoints.
This can prevent
- flyaways due to user errors, or
- catch the corner case where a takeoff waypoint is added to a mission
and therefore the first waypoint is not too far away, however, the
subsequent waypoints are still too far away.
If logger is started very early, orb_exists() will fail for a lot of
topics, they will be advertised within the next few seconds.
Logger already dynamically adds subscriptions during logging, but if we
do that before as well, we'll avoid any delays and having to subscribe
to a lot of topics all at once.
To keep track of the configured interval, we store it as negative file
descriptor, until we do the subscription.
This frees up a considerable amount of file descriptors in most use-cases.
Existing users of orb_exists:
- logger (dynamic subscribe to multi-instances)
- mavlink (orb subscription)
- sdlog2
- preflightcheck (check for home_position)
- wait_for_topic shell command (it's not used)
- orb_group_count() (sensors: dynamic sensor addition)
All use-cases benefit from the changed semantics: they are really only
interested if there is a publisher, not another subscriber.
Paul Riseborough