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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

    • Jakub Oller > Randy April 27, 2015 at 1:49am

      Great. Can you add third servo mode (continuous rotation servo mode) which essentially transfers PID output to servo? It was described before.

  • Ashish Bhatti April 21, 2015 at 9:48am

    Hey guys, appologies for not posting my params been very busy with university work. i need some help though. as part of the project i need to prove i have tracking capabilities, now when i use the telemetry log it only seems to plot the copter data not the antenna tracker data. any ideas? i need to show the bearing of the tracker is justified by the location of the drone. 

  • Keith G April 19, 2015 at 10:13pm
    Good lord....pitch is working. Whatever Randy changed 2 days ago was the fix I needed. It's not perfect but the damn thing works!!! The biggest problem at the moment is that when I try to connect and connect the plane first, it takes at least 20 mins to update the parameters. But it works.

    Any ideas how to speed up the the "get param" when connecting to mission planner. The plane now has the apm and the tracker now has the pixhawk. On the APM I am using uart2 but there is no sr2_param to configure. Any ideas.

    Thanks
    Keith
    • Keith G > Keith G April 22, 2015 at 3:50pm
      After an hour I stopped waiting for the parameters to load and turned it off. Any ideas would be appreciated. Tracker is the pixhawk and the plane has apm 2.6 on uart2. I don't see a setting in the APM for uart sr2_param. Please help.
      • Jakub Oller > Keith G April 23, 2015 at 12:03am

        Why do you insist on using UART2 in the APM? Can you prepare a simple diagram of connections (what is connected where)?

        • Keith G > Jakub Oller April 23, 2015 at 12:31am
          I don't insist but rather require. I originally had the Apm on the tracker and pixhawk on the plane. Since I need usb I had to move telemetry to uart2. As you know, moving telemetry to uart2 requires disabling the telemetry port. So now I have put the apm on the plane and the telemetry is on uart2. The pixhawk is now on the tracker. I made this change during a troubleshooting session and desperation.

          Is there a reason the parameters loading is so slow it can't be used? Any ideas?
          • Sebastian Schürmann > Keith G April 23, 2015 at 3:31am

            I got an APM2.5 in my tracker. I connected it via USB to a Raspberry Pi running mavproxy and 3DR radio to UART2. I soldered pins to the UART2 connector on the right side of the APM board.

            I only changed the baudrate (57600) and protocol (1 = GCS Mavlink) for sr2.

            I can select both vehicle and tracker in MP, I see their position on the map and I can change their settings, too.

            The only thing is, I get a lot of "already got param xxx" during parameter download, after connecting to the tracker. This increases the time for initial connection, but not to 20mins or more. I will have to verify if it is only for the tracker, the vehicle or both.

            I connect via Wifi/UDP to the tracker.

            • Jakub Oller > Sebastian Schürmann April 23, 2015 at 4:22am

              My setup is somewhat similar to yours, but I use WiFi link between Copter and Tracker. Mavproxy runs on my Copter (collects data from Pixhawk and sends them via UDP to Tracker), then another Mavproxy receives data from copter, relays that data to APM on the tracker and to Mission Planner on PC. That way I have all telemetry and video data pushed into one WiFi link. PC is connected to tracker via Ethernet cable to avoid additional radio traffic.

              Mavproxy on Copter side has one master (ttyUSB for Pixhawk) and 2 outputs: one is for tracker and second is optional if I need to connect to Pixhawk directly. I tested 2 scenarios, the third one is still to be tested. All of these scenarios on the tracker side, the copter side remains unchanged:

              1. Mavproxy on the tracker has 2 masters. One is for Pixhawk (UDP connection) and another is for APM on the tracker. It also has one output for Mission Planner. In that scenario I see both units on my Mission Planner, but I can only talk to one of them (the one, that was listed as a first master)

              2. Mavproxy on the tracker has 1 master connected to Pixhawk (UDP connection). It has 2 outputs - one for APM on the tracker (ttyUSB), another for Mission Planner. In this scenario I connect my Mission Planner directly to Pixhawk's mavproxy. Mavproxy on tracker is only receiving data from target and relays it to APM. This scenario works well, but I don't see the tracker on my Mission Planner and I can't communicate with it. I have no problem communicating with Pixhawk in this scenario as I skip tracker when I connect to it.

              3. Tracker runs 2 separate Mavproxys. One has Pixhawk on it's master (UDP connection) and APM's uart2 on its output and the second one has APM's USB port on master and UDP connection to Mission Planner on it's output. That way data will be transfered from Pixhawk into APM's uart2, then APM will process it and forward to Mission Planner via USB. This scenario will appear as identical to the one described in antenna tracker's howto, as the APM will relay all data.

              As for the "allready got param" problem - check the ID's again and make sure, that the telemetry rates you use are within APM's baud rate. What I mean, is that maybe (just maybe) there are communication errors due to big stream of data going out of APM's USB port. After all APM is outputting double the data it was meant to (it outputs it's own telemetry and pixhawk's telemetry). Try increasing APM's baud to as high as it goes (I can't remember now but it is stated in parameter description) and enter the same value in your Mavproxy script. If you do it wrong you won't be able to communicate with APM unless you upload the firmware from scratch, so I recommend saving your current parameters before you proceed. 

          • Jakub Oller > Keith G April 23, 2015 at 1:18am

            In my case I had a slightly different setup, since I used mavproxy and ethernet connections. I found, that I can communicate with only one device at a time (depending on which is listed as a first one in mavproxy). I could see my tracker and my copter on mission planner (both were sending their location properly) but I could only read/write params to one of them. I think this was related to mavproxy and it is not relevant to your problem. From what I know data should be relayed from one uart to another if you have your ID's set properly. Moreover, Mission Planner should see 2 different devices and ask you which one you want to connect to. You probably allready did that, but try it anyway:

            1. Update Mission Planner to the latest version

            2. Update Antenna Tracker to the latest version if it works for you (servo wise), if it doesn't try my version modified for continuous rotation servos 

            3. Update your target (plane, copter, rover)

            4. Connect to each one individually (by USB) and verify their Mavlink ID: It doesn't really matter what number you enter, they just have to be different (I have my copter set to 1 and tracker set to 10)

            5. Verify your connections. Is your connection similar to this? (except you switched pixhawk with APM)

            PIXHAWK telem1 port-----telemetry radio----air----telemetry radio-----APM uart2 port----APM USB----PC with MP

            6. Last one - did you phisically move the telemetry on APM to uart2? You need to cut traces on the APM board and solder new jumpers.

            Detailed description (and preferably drawing/picture) of your setup would help a lot.

            • Keith G > Jakub Oller April 23, 2015 at 8:19am
              I do make the change to the board. All was working, connection wise, untill the latest changes in the master. Everything else is as described.
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