Developer

figuring out the Antenna Tracker

3691139590?profile=originalNot many people know but we have an piece of open source software for controlling an Antenna Tracker.  It's been built by Tridge (Arduplane lead developer) for use in the outback challenge.

Sadly we have no documentation and, as far as I know, nobody except Tridge has used it.  Still given Tridge's track record on building great software I suspect it works well and if it doesn't, I'm sure we can fix it.  So to not let this piece of code go to waste, I'd like some help from people who are interested to give it a try and help me figure out how it works.

Here's the little that I know:

  • It runs on any of our supported board (APM1, APM2, PX4, Pixhawk, Flymaple and perhaps VRBrain)
  • For APM1/APM2 users building the code is as easy as opening our hacked ArduinoIDE and selecting File > SketchBook > Tools > AntennaTracker and then building in the normal way.  For PX4/Pixhawk, our autobuilder doesn't automatically build a binary but I can provide one if people are interested.
  • It can control a Pan and Tilt gimbal like this or this found on servocity.com.
  • It may or may not require a GPS
  • It must somehow receive vehicle position updates from the ground station which has the telemetry radio that is connected to the vehicle. Maybe through a USB cable.  Tridge probably uses the python ground station, MAVProxy, to passthrough the vehicle position data to the AT but perhaps we can get MichaelO to build out a similar feature in Mission Planner.
  • I imagine this antenna tracker could also be used to keep a camera focused on the vehicle which might be good for easing the burden on creating videos of our vehicles.

So if you want to give it a try please do and stick any findings, questions or issues below. Alternatively Issues can go into the issues list.

I'll start sticking things into the wiki as they become clear.

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      • Developer

        Thanks Ted for verifying!

        Im using a real tracker and it was indeed a setup issue.

        It came to life shortly after posting :)

        • Hi Linus,

          I'm glad it worked for you. I've been meaning to test the tracker out with a virtual copter since it's possible to have the vehicle "fix" the location. I am trying to troubleshoot possible offsets in the tracker versus setting PID values. It's hard to do so on a plane vehicle since the plane has to always be moving.

          I've never flown a copter before -- is the SITL procedure for copter the same as it is for plane? I.e. compile the code per http://dev.ardupilot.com/wiki/setting-up-sitl-on-linux/? For the plane, I just start it with "$ARDUPILOT_PATH/Tools/autotest/sim_vehicle.sh -L <mylocation> -v ArduPlane -w --aircraft <myplane>", issue an "ARM THROTTLE", and then a set rc 3 to something like 1400 to take off.

          Thanks

          -Ted

          • Developer

            Copter works similar in SITL, i tried plane as well.

            Here what i do usually:

            sim_vehicle.sh -L EDDH -v ArduCopter --map --console --load-module=tracker --aircraft trackertest/

            proceed with:

            wp clear, wp list, wp draw, arm throttle, rc 3 1666, auto, tracker start, tracker calpress

            My tracker works fine on yaw axis now but pitch does not work so far.

  • hi all is there a minimum distance before it works my one never points to the quad on testing at home 

    • There is a minimum distance parameter in the full parameter list. Default is 5m (500cm in the list).
  • Has scan stopped working in the latest firmware. When I lose signal it should start scanning but it doesn't. Any ideas?
  • Read through the whole thread. Great project with some great results. Really neat.

    Any idea how I can get the tracker to point at the same location no matter what and be independent of a telemetry connection? (I want a tracker on my car and it to track a known location and to use the GPS, baro altitude, etc from the tracker itself and not the remote vehicle). I dont need remote updates as the tracked location is always known, just power up location would be good. Just updates from the local tracker side of things. With the antennas I'm using it is more beneficial for what I'm trying to accomplish to track a known area than try and follow the vehicle so altitude, orientation, etc will change on the antenna tracker side, the tracked location will not.

    Hope anyone has any good ideas. I've been trying to go through and figure this out.

    • Developer

      Paul,

      I've been thinking of adding support for the do-set-roi command.  So that you could click on a point on the map and it would just always point at that.  I can't promise when I'll do that but i've been thinking about it for a while.

      • Randy,

        Now that would be great! I was just thinking of having it point to the startup location once it gets its GPS home location but your idea is even better. As adding a command may be a bit out of my immediate know how, I think I may be able to just create another mode that simply tracks the location at startup. If I'm heading down a dead end then please let me know but I can imagine quite a few uses for this.

        Also, thanks for all the work on this and everything Randy - it is people like you and this whole community that make this so great to be be part of.

        • Paul,

          I've modified v0.5 of the tracker to do exactly what you want, since we need to point to a specific GPS coordinate. All I did was to disable the auto-scan mode on loss of signal, and I just feed the tracker GPS Mavlink messages to get it to point. I am happy to attach the source code if you'd like it.

          -Ted

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