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
Yes, there is an AT change log here.
The v0.7.5 added dataflash logging.
I've released a new version (for Pixhawk only at the moment) which is 0.7.4 which I think will fix the problem that some people were seeing with the pitch not moving. I hadn't realised but the pitch control actually works by comparing the baro pressure of the tracker to the baro pressure received from the vehicle. This patch ensure that the tracker asks the vehicle to send it's pressure at 1hz.
I'm really not sure that basing the pitch on the pressure difference is the best idea. The baro is just one sensor which is used as input to the vehicle's EKF that estimates the altitude. It's certainly noisier than the EKF's final altitude estimate. Anyway, I've just (tried) to solve the immediate issue of the pitch not moving for now.
I've also updated the wiki after first going back and resetting all my params to their defaults and doing everything over again. During my test today I didn't actually have any ground station connected, I just had the tracker and the vehicle communicating with each other using 3DR radios. The default parameters were a little jumpy especially in pitch and it was pointing off in the wrong direction when the vehicle was very close indicating the tracker itself didn't know exactly where it was. Still it generally worked.
Sorry for taking so long to figure out the pitch issue!
Randy,
I thought that was already fixed - there are some comments in the code indicating, that tracker specifically asks remote vehicle do send it's data at 1Hz (I thought it included baro). I never experienced that problem but still a good fix to have around.
As for using unfiltered baro - this is the very reason I talked about using GPS alt. Did you take a look at trackers AHRS? I am no expert but I believe it is not as advanced as in Copter firmware, especially when it comes to using accelerometers to compensate baro and GPS. Can you verify that?
Slow telemetry link.
I finally got my tracker put together and everything works but the telemetry is very slow. I have two pare of 3DR V2 915 telemetry radios set to different net id. The MP Link Status shows only 12 to 25% Quality with more lost packets than good ones. It works great with USB and one set of radios but I need the dual radio setup.
I recall that someone else had this problem but this discussion is so long that I could not find the solution. The AP needs a good troubleshooting guide and FAQ.
Can anyone help?
You should chceck frequency range on both radios - if you use the same settings on both pairs they will try to talk at the same time at the same frequencies (at least I think that is the case). Try changing frequencies to separate these radios from each other.
So having built this antenna tracker with a Pixhawk controller, I'm now having issues with Mission Planner communicating with the tracker. The Antenna Tracker "manual" clearly indicates using a second 3DR radio pair between the GCS computer and the controller Pixhawk on telem 2. When I connect in this manner, the GCS radio does not show any indicators.
Does Telem 2 need to be enabled somewhere?
On the actions tab of the Mission Planner where tracker commands are located, nothing seems to make any change to the tracker behaviour. (This is with the Pixhawk controller and GCS connected via telem 1)
Factual instructions are sparse. Any guidance will be appreciated.
Telem 2 needs indeed to be configured in the parameters with the right baud rate and protocol : should be mavlink and 57 for the rate.
You then also need to copy all of the SR1 parameters to SR2 parameters (that defines the different rates at which the different parameters catagories are sent over the telemetry mavlink). For info, SR0 are the rates for a USB cable connection. SR1 for the telem1, SR2 for telem2, etc.
Roger that. Found settings in full settings screen. Telem 2 talks now. Thanks for the reply.
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