Mission execution specifics (PX4)

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Main Page UgCS Connecting UgCS and PX4

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Mission action support

Flight plan element / action Support Notes
Change speed Yes See section Vehicle speed in mission below.
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 below.

Vehicle speed in mission

Vehicle speed in mission depends not only on the speed set for each waypoint but also on maximum climb and descent rates. For best results make sure the "Max climb rate" and "Max descent rate" specified in UgCS Vehicle Profile is 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 mission and parameters MPC_Z_VEL_MAX_UP or MPC_Z_VEL_MAX_DN. Consider route consisting of 2 waypoints:

• WP1 at altitude 30m, speed:1m/s

• WP2 50m apart at altitude 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 "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 route. If 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 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 heading WP action will make vehicle to change heading accordingly. For waypoints which 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 uploaded route will be ignored and vehicle will always point to the next WP by default.

VTOL heading

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

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