Moving platform takeoff and landing

ArduPlane VTOL Plane
, , ,
1

I’m currently working on ArduPilot’s “Moving Platform Takeoff and Landing” functionality but have encountered some issues.

For example, I’m unsure if my P900 radio meets the requirements. Using its broadcast mode, I’ve connected two devices (a rover and a plane) to one ground radio. I can switch between them in the top-right corner of Mission Planner—one with ID 1 and the other with ID 17.

From the official documentation, I understand that I need to send the set fwdpos true command in the MAVProxy terminal to forward the beacon’s GLOBAL_POSITION_INT packets to the plane. However, nothing happens when I enter set fwdpos true.

I haven’t connected a GPS device yet, so I’m not sure where the problem lies.

2

What do you expect to happen when you issue that command?

You can also right click on the Mission Planner Map and select “Forward between links” in the context menu. Not sure why it’s there but I believe that will have the same effect.

Is there a gps on the “rover” separate from the one you have yet to plug in?

3

Thank you very much for your reply.

Currently, I have not connected any devices to the rover or the plane except for the P900 radios. I’m unsure what a successful setup looks like, as there are basically no such cases available online.

Regarding the “Forward between links” feature in Mission Planner that you mentioned, I have tried using it, but since this is my first time, I don’t know what to expect or what the correct behavior should be after clicking it.

4

If everything is working correctly, after you click “Forward between links” in Mission Planner you should be able to see the “Have beacon” message coming from the plane in Mission Planner.

You can also press F12 in Mission Planner and open MAVLink Inspector to look at the MAVLink traffic between the plane / rover / GCS, and check whether there are any LANDING_TARGET (149) messages being sent and forwarded.

Also, just to confirm: did you start the Lua script on the plane ? I didn’t see that mentioned in your description.

1 Like
6

Thank you for your reply.

Lua scripting is available, and the corresponding parameters have been enabled. However, Mission Planner currently displays the message: “No Ship: no beacon”.

I accessed the MAVLink Inspector and can see both Vehicle 1 and Vehicle 17. Upon checking the GLOBAL_POSITION_INT packets from Vehicle 1, they are being transmitted at a rate of 2 Hz.

Regarding the LANDING_TARGET message you mentioned, where can I view it?

As for the “Forward between links” feature, I just tried enabling it for both the rover and the plane, but there was no noticeable change in the system behavior.

There are no icons related to this functionality visible in Mission Planner. I wonder if this is due to testing indoors?

8

I have a fundamental question: how should I configure the P900 radios in PMP mode when using three radios, one for Mission Planner, one for the rover, and one for the plane?

9

I’m sorry, I miss-spoke earlier.
With Forward between links enabled, in MAVLink Inspector you should be able to see the GLOBAL_POSITION_INT messages from Vehicle 17 being forwarded to Vehicle 1.

Please put both Vehicle 1 and Vehicle 17 outdoors where they can get a good GPS fix, and make sure you can see both vehicle icons on the Mission Planner map.
If the Lua script on the plane does not receive the valid target position and velocity from the other vehicle, it will also report “no beacon”.

10

You’re absolutely right; it’s confirmed that useful position data cannot be obtained indoors.

When I took the equipment outside today, the “no beacon” message disappeared. When I set SHIP_AUTO_OFS = 1, the FOLL_OFS_X/Y/Z parameters started showing data. However, the Z-axis value displays -400m, and I’m not sure where the problem lies yet. It might be due to the crudeness of my equipment resulting in poor positioning accuracy.

Thank you very much.