Copter: use 3d vector from plnd to slow down

[chobitsfan]

This PR allows distance field in LANDING_TARGET been used to slow down descend speed. It is tested with CubeBlack in RTL 2022-08-25 10-24-58.zip Hi @kapacheuski , would you mind taking a look at this PR? Thank you very much

[kapacheuski]

@chobitsfan Hi. It looks like we are thinking some way! I think it needs to be implemented. By the way, we need to keep in mind that the distance to target != altitude in general. But it is approximately the same in case of deviation from target < 30 degrees. So I will be happy to test it when my PR (#21556) is merged (I have no camera-based landing system so I can test only using MAV_FARME_BODY_FRD (or any NED) messages). Anyway if you have the possibility to build my branch (#21556) and confirm that is working with your setup (camera-based system) - it will be awesome and speed up (I hope) the merging process. Let's keep in touch!

[rishabsingh3003]

@chobitsfan on the call this PR was approved. We'll merge it after it has some testing

[chobitsfan]

Thank you. I will try to test it when weather condition is ok.

[chobitsfan]

flight test ok CubeBlack, Raspberry Pi and camera send LANDING_TARGET to FC, no rangefinder, RTL log 2022-09-15 15-40-51.zip video https://youtube.com/shorts/04SDixARTS8?feature=share

[chobitsfan]

pixhawk 4 mini, irlock and lightware sf-20 rangefinder, flight test ok log 2022-09-19 15-30-19.zip

Hi @rishabsingh3003 I have tested it with companion computer (LANDING_TARGET) and irlock (with rangefinder). Both configurations work well.

[rishabsingh3003]

@rmackay9 can you merge this one if you like it?

[rmackay9]

Merged, thanks! sorry for the delay.