PX4 Integration Guide

Connect any UAVLAS precision landing system to PX4: MAVLink port parameters, LANDING_TARGET check in QGroundControl and precision landing missions.

ULSDC-PBIG161026-PX4 · version 1.0.0 · issued October 16, 2026
The numbered PDF is the controlled copy: download it from the portal.

Introduction

Purpose

This guide describes how to connect a UAVLAS precision landing system to a PX4 autopilot, configure the MAVLink port, verify the LANDING_TARGET message and fly a precision landing mission.

Intended Audience

Integrators and operators setting up precision landing on PX4 vehicles.

Applicability

This guide applies to every UAVLAS precision landing system that connects to the autopilot over MAVLink: ULS-XCopter, ULS-ProCopter, ULS-Heli and ULS-XSpot. Product-specific installation, pinouts and wiring are in each product’s Operation Manual and Interface Control Document.

Integration

Preparing for Integration

  • Download the latest version of ULS-Tools. Connect all UAVLAS devices to a PC and update their firmware before proceeding.
  • Update the autopilot to the latest PX4 version. The stock PX4 firmware supports UAVLAS systems; no custom build is needed.
  • Install the transmitter and receiver(s) and wire the receiver to a free autopilot UART (TELEM) port. Pinouts and wiring diagrams are in the Interface Control Document and Operation Manual of your product.
  • Configure the transmitter in ULS-Tools.
  • Configure the receiver in ULS-Tools (on dual-receiver systems, configure both receivers).
Generation 3 receivers (ULS-Heli-G3, ULS-XSpot-G3) have an RS422 interface. A UART-only autopilot needs the ULS-XX-UART-RS422 onboard adapter.

The system communicates with PX4 over MAVLink 2 and reports the target in MAV_FRAME_LOCAL_NED.

Example of receiver configuration:

Receiver configuration for PX4

Figure: Receiver Configuration for PX4

Configure PX4 Autopilot

Values are provided as an example (Pixhawk4-mini AP):

PX4 ParameterValueComment
MAV_1_CONFIGTELEM/SERIAL4Requires reboot to apply the next parameters
MAV_1_FORWARDEnabledForward MAVLink messages
MAV_1_MODEOnboardSet link mode to onboard
SER_TEL4_BAUD460800_8N1Must match the UART baud rate set in the receiver configuration

Table: PX4 Autopilot Configuration Parameters

Running and Testing

After configuration and wiring, power up the drone and transmitter. In QGroundControl, go to Analyze Tools → MAVLink Inspector and check for the LANDING_TARGET MAVLink message.

If the vehicle is providing a LOCAL_POSITION_NED message to the UAVLAS system and is hovering over the beacon, the field position_valid = 1 will appear in LANDING_TARGET.

To perform precision landing, create a flight plan and enable the Precision Landing option on the landing waypoint.

LANDING_TARGET may be unavailable when connected over USB. Use a telemetry channel (UART modem, etc.) to connect the drone to QGroundControl during testing.
LANDING_TARGET in QGroundControl

Figure: LANDING_TARGET Message in QGroundControl

For additional information, see the PX4 documentation at https://docs.px4.io/main/en/