How for feed vision-based latitude, longitude and alt into the EKF?

ArduCopter
1

I have a module for image matching between realtime image and google map which can offer only latitude\longitude and altitude.
How can I set the firmware to use the module for localization or navigation?
My vehicle type is plane.

2

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How to integrate vision-based GPS data into the EKF?

To integrate vision-based GPS data into the Extended Kalman Filter (EKF) in ArduPilot, you need to configure the system to use external navigation data sources. This process involves setting up the EKF to accept inputs from vision-based systems like the Intel Realsense T265 or similar devices. Here’s a step-by-step guide:

  1. Enable EKF3: Ensure that EKF3 is enabled, as it is the default estimator for ArduPilot 4.1 and higher. You can enable it by setting the following parameters:

    • EK3_ENABLE = 1
    • EK2_ENABLE = 0
    • AHRS_EKF_TYPE = 3

  2. Configure Sensor Sources: Set up the primary and secondary sensor sources. The primary source is typically GPS, while the secondary source can be your vision-based system.

    • For the primary source (GPS):
      • EK3_SRC1_POSXY = 3 (GPS)
      • EK3_SRC1_VELXY = 3 (GPS)
      • EK3_SRC1_POSZ = 1 (Barometer)
      • EK3_SRC1_VELZ = 3 (GPS)
      • EK3_SRC1_YAW = 1 (Compass)
    • For the secondary source (Vision-based system):
      • EK3_SRC2_POSXY = 6 (External Nav)
      • EK3_SRC2_VELXY = 6 (External Nav)
      • EK3_SRC2_POSZ = 1 (Barometer)
      • EK3_SRC2_VELZ = 6 (External Nav)
      • EK3_SRC2_YAW = 6 (External Nav)

  3. Disable Fusing of All Velocities: Set the EK3_SRC_OPTIONS parameter to 0 to disable the fusing of all velocities.

  4. Switching Between Sources: Use a 3-position auxiliary switch to manually switch between the primary and secondary sources. Configure the switch with:

    • RC8_OPTION = 90 (EKF Pos Source)

  5. Testing and Validation: Perform bench and flight tests to ensure the system switches correctly between GPS and vision-based data. Monitor the EKF health and position accuracy using a ground station.

For more detailed instructions, refer to the GPS / Non-GPS Transitions documentation.