Mission execution specifics

Mission action support

Flight plan element / action	Support	Notes
Change speed	Yes
Wait	Yes
Panorama	No
Set camera mode	Yes
Set camera by time	Yes
Set camera by distance	Yes
Set camera attitude	Yes
Set POI	Yes	Starting from PX4 version 1.8
Change heading	Yes	See section Heading behavior bellow

Vehicle speed in mission

Vehicle speed in a mission depends not only on the speed set for each waypoint but also on a maximum climb and descent rates. For best results make sure the "Max climb rate" and "Max descent rate" specified in UgCS Vehicle Profile are equal to the rates configured on the vehicle: parameters MPC_Z_VEL_MAX_UP and MPC_Z_VEL_MAX_DN respectively.

Warning!!!
PX4 will not always fly along the straight line between waypoints if waypoints are at different altitudes.

The exact trajectory will depend on the slope angle, speed specified in the mission, and parameters MPC_Z_VEL_MAX_UP or MPC_Z_VEL_MAX_DN. Consider a route consisting of 2 waypoints:

• WP1 at an altitude of 30m, speed:1m/s

• WP2 50m apart at an altitude of 20m.

• MPC_Z_VEL_MAX_DN is set to 5m/s

PX4 vehicle at WP1 will descend rapidly at 5m/s vertical speed while maintaining ∼1m/s ground speed and then fly horizontally towards WP2.

Workaround for the problem is to use the "Safe" Trajectory type. In that case, UGcS will generate only vertical and horizontal segments.

Heading behavior

Vehicle heading is controlled by "Heading" waypoint actions specified in the route. If the Heading is not specified for the route waypoint then VSM calculates the heading automatically to point to the next WP.

The above behavior can be disabled via Force heading to the next WP parameter. In that case, the vehicle behavior will depend on the autopilot parameter MIS_YAWMODE.

If MIS_YAWMODE is set to zero then the heading WP action will make the vehicle change the heading accordingly. For waypoints that do not have explicit heading action vehicle will keep the last heading.

If MIS_YAWMODE is set to non-zero then all heading actions in the uploaded route will be ignored and the vehicle will always point to the next WP by default.

VTOL heading

Change yaw for VTOL vehicles works only when hovering over the waypoint. The vehicle will always fly with the nose pointing to the next waypoint.

For Yaw action to succeed it must be used together with the "Wait" action.

Flights below Home Location

Warning!!!
PX4 does not support flying below Home Location. Make sure all route waypoints are above HL. See also
Home Location (HL) support.