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Overview

The ORIGIN parameter group (specifically ORIGIN_LAT, LON, and ALT) defines the global anchor point for vehicles operating in a Local Coordinate Frame.

This is primarily used when flying Indoors or in GPS-denied environments using Beacons (Pozyx/Marvelmind) or Visual Odometry.

Key Concepts

1. Anchoring the Local Map

Indoor positioning systems report position relative to a local origin (0,0,0). To allow the GCS to draw the drone on a world map, the autopilot must know where that (0,0,0) point is physically located on Earth.

  • ORIGIN_LAT / LON: The Geodetic coordinates of the local origin.
  • ORIGIN_ALT: The altitude (AMSL) of the local origin.

Developer Notes

  • Library: libraries/AP_Beacon.
  • Context: Without these parameters, the vehicle can still hover and fly relative to its starting point, but it cannot perform mission-based navigation using global waypoints.

Backup altitude (MSL) for EKF origin

ORIGIN_ALT: Backup altitude (MSL) for EKF origin

Description

Backup EKF origin altitude (Mean Sea Level) used when not using a positioning system.

Values

  • Units: m
  • Default: 0

Description

This parameter sets a fixed "Home" altitude for the EKF when no GPS or other absolute positioning system is available.

  • Usage: Primarily used in ArduSub or indoor non-GPS environments where the vehicle needs a reference point to initialize its navigation filter.
  • Function: If the EKF cannot find a global origin (e.g., via GPS lock), it will use this value (along with ORIGIN_LAT and ORIGIN_LON) to establish its local coordinate frame.

Source Code

ardupilot/ArduSub/Parameters.cpp

ORIGIN_LAT

deg
Default 0
Range -90 90

EKF Backup Origin Latitude (ORIGIN_LAT)

Description

ORIGIN_LAT (working with ORIGIN_LON) provides a "Start Map Here" coordinate for the drone's position estimator (EKF).

If you are flying indoors or using an ArduSub ROV without GPS, the drone doesn't know where it is on the planet. However, it still needs a global coordinate to satisfy internal math and GCS mapping. This parameter allows you to manually set that starting point.

Tuning & Behavior

  • Usage: Set this to the coordinates of your dive site or indoor arena.
  • Significance: Even if you only care about relative movement (e.g. "Move 5 meters left"), providing a valid origin ensures that logs and maps show your vehicle in the correct general area of the world.
View Source

ORIGIN_LON

deg
Default 0
Range -180 180

EKF Backup Origin Longitude (ORIGIN_LON)

Description

Provides the manual longitude coordinate for an EKF origin without GPS.

View Source
Sensor Orientation Configuration (ORIENT) On-Screen Display Configuration (OSD)