Fixed Wing Autoland

The autopilot will automatically land on a landing waypoint.

Usage

Set a landing waypoint at ground altitude in QGroundControl. The landing direction will be defined by the direction of the previous waypoint (last mission waypoint) towards the landing waypoint. The system will try to touch down at the landing waypoint position.

Setup

These are the main parameters for landing. Note that the maximum accuracy for a good ground estimate is 2-5 meters based on barometric pressure and GPS and that a laser distance sensor is required for spot-on reliable landings. The system will land fine without, but might under or overshoot by a few meters due to altitude variations (needs more space / longer runway).

  • FW_LND_ANG - The landing slope
  • FW_THR_LND_MAX - The landing throttle (maximum throttle when touching down, which is defined as being below FW_LND_TLALT)
  • FW_LND_TLALT - The altitude at which the throttle will be limited
  • FW_LND_RFRALT - If set to 1, the system will use a relative altitude estimate if available, such as a laser distance sensor
  • FW_LAND_HHDIST - The heading hold (only small roll angle allowed) horizontal distance. This parameter ensures that the system will not touch the ground with one of the wings.
  • FW_LND_FLALT - The vertical ground distance / relative altitude at which the system starts to flare.

Landing Slope and Final Flare

laser sensor for autoland

If a precise landing is required or if it is a bigger/heavier aircraft, a laser sensor is required to get precise results.

There you have to set FW_LND_USETER on 1 to integrate the terrain estimate with laser. Do double check/adjust the SENS_BARO_QNH to the actual AMSL height. Otherwise it will not work precise.

QGroundControl

You have to plan your autolanding by setting waypoints in QGroundControl. You should plan a pattern like in general aviation with downwind, base and final.

This is how a successfull autolanding could look in QGC:

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