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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      • eagle eyes tracker

        currently using Futaba S3000 position servo's but I have ordered some CR servos to see if that makes it easier.

        Have tried the default pids and suggested Pids here.

        P 0.2

        I 0.1

        D 0

        IMAX 4000

        slew 2

  • My quad is set to node 0 destination 65k

    My ground station is set to node 1 destination 0

    My AntennaTracker running on APM 2.6 is set to node 2 destination 0

    I can connect to the Quad from mission planner but I am not seeing the AntennaTracker in mission planner.

    Using RFD 900s on all 3.

    I have confirmed by reconfiguring them all that each can talk to each device individually so I think it is something in the way I have set this up.

    Any ideas, I really am keen on a minimalist setup without USB.

    • ok, further update

      so if I connect the AT to the USB port on the GSC and then use the swarm feature in MP then I can see both the antenna tracker and the quad.

      Then if I disconnect the USB and connect an RFD900 to the Telem1 port on the APM2.6, the RFD is on the network but I can't get it to show up in MP.

      I cant't figure out how to get the traffic from the AT to go to the GSC via the quad at radio node 0.

      If someone can point me in the right direction and I can get this working, I'll write up all the configs and instructions required to get AT working as part of multi node network.


    • Further, mavlink settings

      tracker system id set to 9

      Tracker target id set to 0

      Quad system id set to 3

      Could not find a target parameter in the quad so assume this cannot be set

  • Hi All got little issue with my tracker with yaw servo

    https://www.youtube.com/watch?v=AUG27V4BOxg

    YouTube
    • I can see two problems:
      1. The GWS servo turns 360° instead of the "normal" 180°. This means the resolution (°/us) is half as good as with a 180° servo. This makes it more difficult for the tracker to find the right position.
      2. Your trackers mass is distributed relativly far out from the pivot point. This creates a lot of inertia and makes the servo slower to react.
      I would try to set the I term to zero and see if it changes the behaviour.
      You might also try to add some kind of mechanical damper, like a small o-ring under the yaw servos horn.
      • played with pi for some time today with no luck.

        so i change it with HS 5645 all good now no more shaking

        just its not pointing to the plane and slow to respond to moving plane

    • Looks either like bad PID settings or wrong servo type. Please describe your tracker (especially servos). Does it point towards the plane (your movie suggest that)?

      • yes it does point to the plane

        my setup is

        pixhawk V2 the radios are RFD900+ servos are Tilt servo is Hitec HS 5645 MG

        Yaw  servo is GWS S125 1T Sail Winch

        3702720187?profile=original3702720303?profile=original3702720226?profile=original

        • Is your YAW servo a continuous rotation servo? Specs say it isa standard position servo with extended range but I am not sure about that. You should play around with PID settings. Since it points to the plane and your only problem is oscillation it should be a PID issue.

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