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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Thx for these useful info on the parameters. 

I still need to find out why AT does not proxy the quadcopter mavlink to the GCS...

Hi Tim.  I assume you have made no code changes in your repository.  If you have you will need to stash them with "git stash" BEFORE you run this command.  See in your post it has the line

Your branch is ahead of 'origin/master-AVR' by 1264 commits.

This means you effectively have master-AVR with all the master changes in it.  So you need to reset back to the head of master-AVR with this command

git reset --hard

This WILL delete any local changes you have made so make sure you stash first if you have anything.

Then go through the make clean, make apm2 again and let us know.

Thanks, Grant.

Grant, thanks for your last suggestion which lead me to a final solution.  I have not made any changes to the files and I don't know why I kept getting the reply that I was ahead of the origin.  No matter what I tried (reset --hard or clean -fd and then doing a pull --rebase) I continued to get a response that I was ahead of the origin.  I finally started from scratch and re-cloned the repo.  After I did this I was able to compile with make.  One more question..As development for AntennaTracker continues will the additions make it into the master-AVR for tracker or will they only be added to master?  Thanks again for you assistance. 

Ok, I found the problem. Again one of these wichcraft reasons: the issue was the quadcopter was unable to make a connection via telemetry, independently of Antenna tracker. Pixhawk would connect via USB but would not connect anymore through radio telem1 (radios themselves were fine as they could be used succesfully to connect with another pixhawk). Could not make it work until I reflashed Pixhawk with firmware (before trying this extreme measure, I tried to reload default params but that did not enable the radio link to work neither).

So the reflashing of the firmware did the trick. Must have been some faults in the telem1 port that has been reset or reloaded in the flashing process ?  These kinds of hardware instabilities are worrying as they happen without identifiable reasons.

Then, I could finally try antenna tracker firmware again. Connected antenna tracker in proxy mode and at least I got some servo movements and saw the quadcopter in the CTRL+X drop down.

Next, outside trials.

Hi Tim.  Glad you got it working.

The AntennaTracker changes will be in both master and master-AVR.  master will have the changes so it works on Pixhawk and Linux compatible boards and master-AVR for APM2 hardware boards.

Thanks, Grant.

I just wanted to follow up:  We got the tracker to work just fine this summer with our PixHawk systems.  Many thanks to everyone in the forum for their advice!

Would you share your setup, changes you made to parameters, and sequence/order you connect things with the group. I'm still struggling. Thanks

Hello,

I've been looking for an answer to this question everywhere and was hoping someone would be able to help me. I had seen that the GPS module from 3dr apparently has a 1-2s lag time associated with it. This affects the GPS based tracking function built into mission planner.

What I'm hoping to find out is:
1. From anyone's experience is this lag time unavoidable (Sorry I know this isn't related to the AT firmware)
2. Does this same lag find it's way into the alternative approach that is the AntennaTracker system? Or does it only rely on compass and elevation data to determine location without a GPS based lag?

Any help from anyone with experience with either of the two systems would be greatly appreciated!:)

I have been working on the antenna tracking firmware version 0.7.3 for my senior design project. I can get a HITL working with a simulated plane and the antenna following it properly. But I can not get the antenna current heading to align with the direction to the next waypoint. The antenna's heading on mission planner is roughly 30 degrees off the actual antenna direction. I have tried adjusting the compass' yaw to account for this with no luck. Anyone else had this problem?

I had a 180 degree offset between current heading and next waypoint; I solved it by adjusting (trial and error) the "reverse" parameter of RC1 and RC2. This cnages the direction of rotation of the picth and yaw servos. You have to find the right combination (4 possibilities)...

Another issue I am blocked at in figuring out antenna tracker;

I have the antenna tracker configured in proxy mode (copter linked via 3DR radio to <-> a pixhawk on the antenna tracker with a second radio connected to <-> mission planner).

The antenna tracker firmware is the last 0.7x version.

Both the copter and antenna tracker show up correctly on mission planner's map. All manual, scanning and test servo modes function correctly.

The only issue I'm experiencing is with the Auto mode that tracks only in yaw, not in pitch.

I tried to reset, to turn on copter and tracker in different chronological order, still same issue.

The attached picture shows the status page, where "alt error" is at "infinite" value, which seems weird.

I wonder if the baro altitude information from the copter is received by antenna tracker ? Is this a known bug ?

I'm closely monitoring satellite antenna tracker project on satnogs.org They are on v3 now and have really nice designed hardware part, It is open source project and most components are 3D printable.

Electronic part is simple and efficient. In V3 they started using geared DC motors instead of stepper motors which made whole thing more electrically efficient. I think we are having some common ground here. V2 is mounted inside of plastic box without the need for aluminium beams.

Electronic for V3 is still work in progress, but basically whole thing is controlled with Arduino that can be installed on controller board. I guess that same Arduino with addition of GPS/compass module and 9dof imu can run mavlink, drive motors and serve as nice ground station antenna tracker for APM/PX powered vehicles. 

On the other hand they are not using IMU/Compas sensors in their project as unreliable. Possibly they have to check few things at our forum about sensors calibration. It would be definitely nice to see Lead developers on both projects  communicate on the subject.

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