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.
Replies
It may be possible that you don't really have the latest firmware as previous versions did have a pitch control issue. Try using the "Test" butttons on the Extended Tuning screen to manually position your pitch to verify operation. One other possiblity is that the copter is too close to the AT. You need a good 50 feet (15m) separation.
Manual servo test are fine with the Pitch, it is only in Auto mode that it does not work.
I have also configured the parameter that gives the minimum distance to begin tracking and have set it to one meter for my bench tests.
Worse, Sometimes it works, sometimes it does not. It is like the Auto mode does not trigger in certain circumstances that are undefined and unexplainable.
I worried that this firmware is still too green and needs to mature for a reliable functionning tracker.
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.
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)...
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!
Hi,
I do not succeed to make antenna tracker work. I repost here a question raised on APM forum as it seems to be the place for discussing AT matters.
This is what I tried:
I follow the wiki instructions to setup an antenna tracker, using a pixhawk (driving the antenna tracker servos). Firmware is installed and configured. This is a "proxy mode" setup with AT in the middle. My objective is to use AT for long distance telemetry link to the GCS.
I used the connection scheme of the wiki with a 3DR radio link between the vehicle and the antenna tracker's pixhawk. And then I connect mission planner via usb cable to this pixhawk.
I get in mission planner the icon of the antenna tracker on the map, I get all of the config menus of the antenna tracker.
But I do not see anywhere the vehicle as if the antenna tracker was not connected to any vehicle.
I tried CTRL+X to switch vehicles on the MP display but no joy : no copter in the drop down list, only antenna tracker.
What did I miss ?
Secondary question : what do these two parameters in the antenna tracker config params mean : SYSID_TARGET, SYSID_THISMAV? Should I set them to specific values ? Why is SYSID_THISMAV to a value of 2 by default ?
In MAVLink every device has its own ID. AT also needs to have an ID, thus it is by default assigned with number 2 stored in SYSID_THISMAV parameter (on another thought - the default should be 10 if I'm not mistaken). You can change it to any unused number but there is no need for it (unless you have more than one tracker in your network). Every APM/Pixhawk you have in the same network needs a different SYSID_THISMAV parameter.
SYSID_TARGET is the ID of the vehicle we are currently tracking. Zero means auto detect and it should work fine in most cases. If you feel like changing it make sure that SYSID_TARGET on the tracker is equal to SYSID_THISMAV on the vehicle. SYSID_THISMAV on the tracker is not relevant, but it needs to be different.
To make it easier to explain - you can build a system that consists of 2 trackers. First tracker with SYSID_TARGET = 2 and SYSID_THISMAV = 1, second tracker with SYSID_TARGET = 1 and SYSID_THISMAV = 2. These 2 trackers should point exactly at each other since tracker 1 is pointing at device nr 2, tracker 2 is pointing at device number 1.
As for your configuration problems - this is still work in progress and you need to experiment a lot. Try getting through this forum as you may find a lot of similar issues. Maybe your copter also has SYSID_THISMAV set to 2 which would prevent MP from seeing it. Verify that your devices have different numbers.
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...
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.
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