Publish Gimbaled LRF distance through mavlink camera protocol

[dirksavage88]

Feature Request

Publish Gimbaled LRF distance through mavlink, instead of just the backend mount message

Is your feature request related to a problem? Please describe.
Currently the gimbal LRF distances for the viewpro and SIYI are published via an ardupilot specific mount message, see

ardupilot/libraries/AP_Mount/AP_Mount_Backend.cpp

Line 477 in c40422c

rangefinder_dist : rangefinder_dist,

However this implementation just passively publishes the distance values, whereas these range values can be consumed by some (LightwareLidar is one such gimbal LRF) mavlink-enabled gimbal/camera payloads to focus on a POI and would be a valid use case for these LRF values given the mavlink camera protocol v2.

Describe the solution you'd like
Instead of only publishing a custom mount message specific to ardupilot, publish via MAV_CMD_SET_CAMERA_FOCUS with focus type set to range and the value in meters from the POI

Describe alternatives you've considered
modifying the current implementation to publish gimbal LRF values to MAV_CMD_TRACKING_GEO_STATUS, however the camera protocol/manager would have to be actively tracking to send distance values for focusing?

Platform
[ x ] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Submarine

Additional context
Willing to contribute to push this forward, but I am new to ardupilot contributions.

[rmackay9]

Hi @dirksavage88,

Thanks for the enhancement request. Technically it's easy to add the rangefinder distance to a mavlink message, the issue is that I don't think we really have a good message at the moment. MAV_CMD_SET_CAMERA_FOCUS and MAV_CMD_TRACKING_GEO_STATUS are both commands so those probably aren't appropriate.

It's probably best if we raise an issue on the MAVLink issues list and get input from @hamishwillee and others.

[hamishwillee]

I don't understand where the information is coming from or going to, but rangefinders are expected to publish information using https://mavlink.io/en/messages/common.html#DISTANCE_SENSOR . Posting an issue as Randy suggests is a good idea (if this doesn't do what you want) so that I can share more broadly among mavlink users.