Air Traffic Avoidance: UTM

Air Traffic Avoidance: UAS Traffic Management (UTM)

PX4 can use MAVLink UTM_GLOBAL_POSITION messages to support simple air traffic avoidance in missions. If a potential collision is detected, PX4 can warn, immediately land, or return (depending on the value of NAV_TRAFF_AVOID).

:::note This implementation is exactly the same as for ADS-B traffic avoidance (except for the source of other-vehicle data). For more information see implementation below. :::

Configure Traffic Avoidance

Configure the trigger distance and action when there is a potential collision using the parameters below:

Parameter	Description
NAV_TRAFF_AVOID	Enable traffic avoidance mode specify avoidance response. 0: Disable, 1: Warn only, 2: Return mode, 3: Land mode.
NAV_TRAFF_A_HOR	Horizonal radius of cylinder around the vehicle that defines its airspace (i.e. the airspace in the ground plane).
NAV_TRAFF_A_VER	Vertical height above and below vehicle of the cylinder that defines its airspace (also see NAV_TRAFF_A_HOR).
NAV_TRAFF_COLL_T	Collision time threshold. Avoidance will trigger if the estimated time until collision drops below this value (the estimated time is based on relative speed of traffic and UAV).

Implementation

PX4 listens for UTM_GLOBAL_POSITION MAVLink messages during missions. When a valid message is received, its validity flags, position and heading are mapped into the same transponder_report UORB topic used for ADS-B traffic avoidance.

The implementation is otherwise exactly as described in: ADS-B traffic avoidance > Implementation.

:::note UTM_GLOBAL_POSITION contains additional fields that are not provided by an ADSB transponder (see ADSB_VEHICLE). The current implementation simply drops the additional fields (including information about the vehicle's planned next waypoint). :::

Further Information

• ADS-B Traffic Avoidance