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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Replies

    • Developer

      iskess,

      I've been off looking at at AC3.2 mostly but I started back at the Antenna Tracker again a bit today.  I found that I needed to set the PROXY_MODE parameter to "1" so that messages are forwarded on from the Pixhawk I'm using to control the antenna tracker servos to my mission planner ground station.  I've updated the wiki page here.

      I can now connect to the vehicle with the mission planner (passing through the AT) including reading parameters, etc.

      There's still some weirdness, like the mission planner is complaining on it's console that it's seeing a lot of messages that aren't meant for.  Basically I think there's some IDs being set incorrectly during the message forwarding.

      I can tell that the Pixhawk on the AT is receiving the position updates from the vehicle but I haven't checked if it will move the servos correctly or not yet.

      At the moment, I also don't see a way for the MP to send messages to both the AT and the vehicle so I think we will need MichaelO to enhance the MP.  I think he'll be ok to do that for us though.

  • Any idea what kind of control unit for the pan and tilt in the image above is?

  • So does the APM tracker needs a GPS? It seems it would not unless the GCS is mobile.
    Sounds like it needs it's Mag, IMU, and Gyros for attitude info.
    What about baro? Is there a way to feed the baro info into the GCS so it can update the GND_ALT_OFFSET?
    • Developer

      @iskess,

      I use a GPS but it shouldn't be completely necessary.  It's not documented on the wiki yet but there are some parameter that allow you to manually sets the location of the tracker.  I can't remember the names of the parameters immediately but hopefully you can find them in the full parameters list.  Anyway, just set those to the tracker's location and it should work.

      • Thanks for the reply Randy. Is it possible for the tracker to learn its location from the Home location so the lat/long wouldn't need to be manually entered?

        What do you think of the idea of using the onboard baro to adjust the GCS height via GND_SET_OFFSET?
        • Developer

          @iskess,

          I think the idea to use the vehicle's home location if the AT doesn't have a GPS and the location parameters haven't been set is a good ease-of-use enhancement.  Feel free to add the home location enhancement to the to-do list.

          Using the AT's baro to adjust the vehicle's ground pressure param to take account of baro drift is also a great idea.  I'm sure Tridge updates that ground-pressure value on long flights, i don't know how exactly but I'd suspect the AT is used somehow.

          • Thats what I did with mine initially./

            First 3D fix it sees on startup with more than 8 sats it records as Tracker Base, I have a menu option to reset it if it doesn't look right, Height was sometimes a bit off. Just needed to make sure the multicopter was next to the Tracker on startup.

  • We are lot of people who want an easy-to-use antenna tracker. 

    I don't understand why this stuff did not exist in 3DR shop because of frequency/power we are allowed to use in many countries. 

    I've got an Ardustation Mega (2560) with LCD and it's works...certainly not perfect...but it's 'works'.

    (with Ctrl+F Mavlink feed from mission planner, even with X-plane for testing/debugging Or 3DR telemetry OR openLRS with Serial-passthrought (flipflap version) )

    I've seen this stuff  'Mavlink Auto Antenna Tracker'  from CUAV but it's seems not to be real...

    Product :  http://item.taobao.com/item.htm?spm=a1z10.5.w4002-2343226222.87.M9S...

    Video presentation :  http://www.tudou.com/programs/view/YFwc1FnSj1U/?resourceId=0_06_02_99 

    This stuff seems to have compass. 

    If only we could find a working MAAT like this, finally, many Arduplane/copter/rover users will be happy....

    I will be happy to test Antenna Tracker 1.01 (via MP) but I've no MPU/Baro/compass on my Ardustaton Mega...

    Perhaps when I'll bought Pixwhawk, my APM  will become Antenna Tracker ? 

    • Looks like someone hacked a MyFlyDream antenna tracker to use MAVLink messaging. Eventually, this slip ring type trackers get dirty and have electrical open circuits here and there. But it is a nice effort for a mere $300. Does it include everything, including P&T?

      Yes, you need a compass on the tracker to tell it which way is North during initial set up. There may be auto calibrating ones now. They will still need a compass to orient North and you will need to be somewhat level to have correct elevation. Slip rings are very handy for providing >360 degree rotation. If you've ever tried a tracker without them, you know exactly what I mean. :-)

      • Actually, in my home made tracker I fitted a a tilt compensated compass. I can just drop the unit down anywhere :-)

        I can pick up the base unit while its busy tracking :-)3702666781?profile=original

        3702666930?profile=original

        3702666956?profile=original

        3702666861?profile=original

        3702666984?profile=original

        Built and programmed in about a week. Its a bit rough but it works. Got bored one weekend and decided to see if I could get one to work. Haven't really used it, just a wee exercise to keep the old grey matter churning.

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