Not 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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The open360tracker sketch runs on an APM2.5, too. The only APM2.5 I had, had the internal compass disabled, so I did not use it.
I use a Crius Aio Pro which is also powered by an Atmega 2560.

Is there a need to change something in code, if I want to use it with my APM 1.4, or can I directly compile and flash it  into AMP ?

Hello! I am building a very high gain parabolic dish system - I wanted to ask how accurate the antenna tracker is in degrees?

What would be a reasonable maximum gain for a parabolic dish on the antenna tracker? Would 30 db be too much? 

Thanks!

Hello,

Trying deseperatly to make the antenna tracker firmware work, I succeeded so far to make use of SITL to simulate a vehicle to be able to test the real antenna tracker based on the simulated positions of the vehicle.

I use a AUAV-X2 boartd on the antenna tracker (same as Pixhawk) and an external compass. GPS position has been fixed for testing.

I found two blocking issues/bugs in the antenna tracker firmware (in addition to the already known blocking issue the pitch does not track at all):

  • Bug 1 : the reversing of servo movement is without effect. Changing it in the full param list or on the GIU of mission planner does not change the servo rotation direction, rebooting Pixhawk after these change does not solve the issue. Picture below:

  • Bug 2 : Yaw tracking stops after reaching the servo position limits. It is supposed to do a 180 deg reversal, but it does not (I sue 180 deg servos in pitch and yaw). See picture:

These three bugs make antenna tracker firmware currently unusable. There does not seem to be any improvements more development follow up on this firmware, a pity.

I will have a look at the 360openTracker open source solution as an alternative.

Hugues,

I agree with your assessment and I'm glad that you were able to get SITL to simulate a vehicle and test the APM AT.

Hopefully, we just have to be patient and wait a bit longer. Priorities change so it is up to the community to find others that are interested in the project and have the skills to modify the code. Perhaps we will get lucky and Randy or Jacob will return. One other thing you might consider is to open a ticket with your findings using the Github Issue Tracker.

Hi Greg,

Will link this to the Github issue tracker. Thx for the suggestion.

I will compile a summary of my experiments. I can get the tracker to track but only in the positions limits of the servo (no reversal) (maybe it works better with continuous rotation servos ?) and had to discover by trial and errors what works and what does not, including a non documented way of how you physically have to position the external compass versus the moving plate, for the tracker to read a good heading (and I can tell you it is counter intuitive).

So half joy, but already glad I can track in a limited 180 degrees.

I have a tracker that is working well but it has standard servos. I would like to put a continuous rotation on the yaw and keep my standard servo for pitch. Are there parameter settings that will allow this combo?

Also what’s the latest on firmware development? I have been using the custom firmware because the pitch never moves with the latest firmware.

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I have a tracker that is working well but it has standard servos. I would like to put a continuous rotation on the yaw and keep my standard servo for pitch. Are there parameter settings that will allow this combo?

Also what’s the latest on firmware development? I have been using the custom firmware because the pitch never moves with the latest firmware.

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Hello,

Does any body have any idea of the maximum accuracy of the antenna tracker system?

I do not want to build a system where the gain is too high for the tracker to deal with, it would be terrible if it "missed" the aircraft.

I've never measured it but I think it's within a couple of degrees at least at longer ranges.

Hi Mike,

experience with ardutracker can vary so much from people to people although using the same firmware, which I believe shows how "green" it still is and how ultra-sensitive it is to setting right a certain combination of parameters : for example, in my case, I have succedded to make the pitch work but only with standard positional servos and only if you define a range of movement no more than 90 degrees (although the servo could do more)  and only with yaw tracking that can only be done within180 degrees  and only without reversal contrarily to how it is supposed to behave. Some people have made it work but it remains a mystery why it sometimes works for some and sometime not for others. I suspect that some combinations of parameters work and some other combinations does not work. For me at the moment it is pure trial and error (it took me months banging my head on the walls to have something working, but still in a very limited way)

Like you, I would like to replace the yaw position sevo by a continuous rotation one. I believe the servo type in the firmware is set for both pitch & yaw servos, unfortunately not separately configurable.

Maybe we should call for a group of volunteers, among which some are developers, to develop forward the current Ardutracker firmware base ?


We need to talk Randy into coming out with more Beta versions so we can find out what works and what does not. When he releases a beta version he needs to post his exact setup so we will have a starting set of parameters that’s known to work together. I have asked about gains and other things but never get any useful answers.

I am not a programmer but I do have time to do some beta testing. I have the Servo City mechanics (7:1) with a custom pinion gear to get me 360 on yaw. That works well with the Jakub0.7.2 custom firmware. With that firmware the two telemetry modem option is not supported. I solved that problem by using RFD900+ multi-point setup. It works well but would be a bit of a challenge for someone starting out from scratch.


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