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figuring out the Antenna Tracker

Posted by Randy on July 25, 2014 at 8:01pm

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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Tags: antenna, obc, open, source, tracker
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Replies

      • Greg Covey > Greg Covey August 2, 2015 at 8:43am

        One other observation on the 2nd telemetry link from the AT to GCS. If the MRC is unpowered so that there is no primary telemetry link from the AT to MRC then the 2nd telemetry link from the AT to GCS seems to connect rather quickly. This seems to add to the MavLink collision theory. Both my telemetry links use the same frequency but different net IDs.

  • Jakub Oller July 31, 2015 at 2:15pm

    I tested 0.7.1 firmware today and pitch indeed doesn't work. I set up a simulation environment (as simple as following a howto on ardupilot.com) and PITCH stays at +45 degrees (my fork). On official 0.7.1 it will most likely stay at 0 degrees. I am working on a fix and I am quite determined, since I want to fly my plane tomorrow morning :) I will report back as soon as I have some results.

    Randy,

    I've seen that you added readme.txt into master and I feel called to the whiteboard - I will try to write something in there when I'm done with the fix :)

  • 3qs7z40lxxok2 July 31, 2015 at 7:18am

    how does one slow the servos down

    • Jakub Oller > 3qs7z40lxxok2 July 31, 2015 at 2:45pm

      It depends on what type of servos you use. With official firmware and classic servos I don't think you can do this. With CR servos you can simply limit RC_MIN/MAX values. 

      Max servo speed (based on angular velocity) is on my todo list.

  • palo sestak July 28, 2015 at 2:47pm

    Hello guys,

    today I put into service AT loaded with firmware build from Jakub Oller (thanks Jakub again). I set it somehow (indeed not optimal PID settings) but it works, ugly but works. Not tested it in the field yet, perhaps in the weekend. Now I would like to know  what application I can use in the field since I have only android tablet. On the bench I connected it with MissionPlanner on PC and it works well - I can switch between MRC and AT, data from MRC flows well through AT to MissionPlanner. So I hope in the field it will work. But In the field I can only use Android tablet. When I tested it with andropilot and droidplanner on Android it didn't work.It works only when I connect Android application directly to MRC via telemetry link without AT in between.

    Have somebody any hint on another application I can use on Android? Guess GCS doesn't work on Android.

    • Sebastian Schürmann > palo sestak July 29, 2015 at 1:03am
      I tried a direct connection via USB OTG from my android phone. The only app that was able to establish a connection was 3dr tower, but it had issues with two vehicles (tracker and copter) being connected at the same time. The HUD and the parameters were changing between the two every second, so it was unusable. If you have a few bucks to spare, you could buy a used laptop to use it in the field.
      I bought a Dell e4300 for 150€, bright non-glossy screen, readable outside on a sunny day. I just added a SSD and it now boots to Window7 desktop in about 20s.
    • Sebastian Schürmann > palo sestak July 28, 2015 at 9:49pm
      I have a Raspberry Pi connected to my APM2.5 (running tracker0.5) via USB. Telemetry is connected to UART2. This setup works fine. I only used it with PC / Laptop so far, but I will add a UDP output to mavproxy and see if any of my android devices will be able to receive the telemetry. With Missionplanner I use UDPCI. I did not find any android GCS that is able to use this too.
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