Has anyone used a pixhawk as a standalone device to assist in mapping using a full-sized fixed wing craft?
I'm thinking about setting up a pixhawk +GPS + 3dr radio in a box that would be powered by a 5v BEC. A camera trigger would be connected to the pixhawk. The way that it would need to work is to fly to the target area, then set the cam trigger distance parameter so that the pixhawk could begin to trigger photos with the correct amount of overlap, and the resulting log would have accurate GPS tags via the trigger events. Once the area was done, set the cam trigger distance back to 0 to stop taking photos.
So is this viable? If the pixhawk is disarmed, can it still be put into auto mode so that it can begin to send the trigger command to the camera? Can this just be done using a tablet and no RC remote?
Is there anything else that would need to be done to make this work?
I deleted my first reply, after realizing "full-sized fixed wing craft" :-)
So you do not need the Pixhawk for navigation but only for triggering a camera. Interesting question! But I guess it could work. The survey mode of the Tower GCS allows you to set CAM_TRIGG_DIST automatically when reaching the first WP - and set it back to 0 at the end of the mission. WPNAV_RADIUS must be set pretty high I guess to hit the first WP. Then it should start triggering. So maybe a setup with only two waypoints should work.
But maybe it is much easier: If you enable logging before arming and change CAM_TRIGG_DIST from 0 to something during flight it should start triggering. However, it will not be possible to automatically change CAM_TRIGG_DIST before arming with a standalone pixhawk setup I guess. You would need some companion board and a mavlink connection.
Thanks for the reply Thorsten.
I guess having a reference for navigation would be helpful, even though the pixhawk would't be involved in control at all. So I would still plan a mission with a grid pattern for the appropriate altitude and overlap, and just download the mission into tower so that the flight path is displayed. The actual GPS position reported there will let us know we're on the correct path.
So I guess the procedure I would try to use is fly to the area, use tower to arm the pixhawk board (via 3dr radio), and then change CAM_TRIGG_DIST to what it should be by manually setting the parameter via tower. I guess I can test this on the bench by using a time interval trigger rather than the distance one.
Hmm hit a bit of a wall here. Can't seem to arm via tower or andropilot. Have disabled all failsafes and checks on the pixhawk, but tower displays' rc failsafe', and andropilot displays 'failure to arm - bad throttle'.
Someone must know the correct way to arm a board without a radio rx connected, and only a mavlink tablet connection?