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
Hi Palo,
I am not sure that the GCS telemetry works yet on any application. There were MavLink collisions reported several screens back. I gave up trying to use it and only talk directly to the AT via USB which is a benefit of using a Pixhawk. I will wait for either Randy or Jakob to fix this issue and the pitch issue. I am not yet certain if Jakub's branch is compiled for Pixhawk or only Arduflyer.
I tested my AT out again today. While Jakub's Yaw_Trim setting worked great for fixing my yaw offset, I decided to try v.0.7.1 firmware for the Pixhawk and it locked my pitch angle in place. The yaw seemed to work fine but the pitch just remained as it started when pointing to the MRC on the ground about 30 meters away. Previously, I never had an issue with pitch.
I did not try to reverse the pitch direction so maybe uploading new firmware changed some of my setup. I may try going back to my previous 0.5.1 firmware and just use the Yaw_Trim setting for now. At this point, I am not certain if using a Pixhawk or Arduflyer provides an advantage. More testing to come...
I also don't see any significant advantages of using Pixhawk over APM. Main advantage of Pixhawk is in EKF filtering and I am not sure AT firmware supports that. The only real benefit of using Pixhawk is in number of telemetry ports - in APM you only get 2 ports if you move TELEM port to UART2 (one port on TELEM, one USB) but for now it is not a big problem.
There seems to be a problem with PITCH in version 0.7.1 (and thus 0.7 since it only differs in a few insignificant places). My guess is that changes in MAVLink prevent AT from reading MAV's baro and thus routine responisble for PITCH calculation doesn't run (this routine is called every time BARO message reaches AT). I will work on that but now I am busy at work with different stuff.
While I was trying 0.7.1 out, pitch did not follow the vehicle. It only moved if I tilted the tracker, keeping the antenna at the horizon all the time.
Doug, I originally chose the Pixhawk for AT for the reason you stated. After initially testing the second telemetry link and having poor results, I focused more on just getting the AT working with the MRC.
I tried to go back to AT v0.5.1 and Mission Planner only seems to offer v0.4 as a previous version. I'm sure the other binaries are located somewhere. Does anyone have a link?
I found the AT binaries here.
The last v0.5 entry is here at AntennaTracker/2015-05/2015-05-17-06:05
It seemed to load fine so I'll test it out to see if the pitch is working again.
I believe the advantage of using a Pixhawk is that I can run two telemetry units on it where APM only allows one. I could be wrong, but I built my antenna tracker to be wire free for full 360 rotation and not worrying about cables getting caught up. One Telemetry unit is linked to air vehicle while the other is linked to my GCS laptop.
So I'm still rethinking whether to gut my HS-785HB for continuous Yaw and keeping it as is. Jakub, where you planning to help produce code for a CR yaw servo yet keep code for a close loop pitch servo (also a HS-785HB)?
I can produce that code for you, that is quick and easy - just remind me when your tracker is done. I still need to solve the problem that everyone seems to be having - pitch not following the vehicle in versions >0.5
Hello,
I'm working with a team of students trying to create an antenna tracker. We've got a PixHawk and GPS unit intalled on an EagleEyes Antenna Tracker frame. We're using the 3DR radio link to talk to the air vehicle, which is plugged into the Telem 1 connector, and a USB cable running from the antenna tracker PixHawk into a laptop computer. We can see both units (air and ground) on the Mission Planner display and we can pull up data from either one. We've loaded in the firmware from this forum and everything seems fine.
However, when we turn on the antenna tracker it goes to 45 degrees pitch up and never changes. We've verified that the MAVLink data is getting to the antenna tracker unit and we can see it on Mission Planner. We've also looked at the barometer data and we can see that it's correctly sitting around 1000 for both the tracker and the air vehicle. We've tried flying the air vehicle and moving it around just by carrying it. The yaw is working fine; it keeps pointing at the vehicle. But the pitch doesn't react at all.
We're using servos on the tracker; yaw is a 360 degree servo and pitch is a 90 degree servo. We've tried adjusting parameters on the pitch servo but other than controlling it in manual mode, nothing seems to affect it.
Can anyone think of something we overlooked?
This is yet another instance of this problem and I still cannot reproduce it in my tracker. Can you tell me where did you download the firmware from? Basically the version available via MP is an official one based on diydrones gitgub. Versions (a few of them allready) found somewhere in my posts on this forum come from my fork. The only possible reason for pitch to face +45 degrees is when my fork of firmware enters "initialization" mode. There is no reason for it to happen with the official version from Mission Planner, since there is no such mode. I need to make sure, that it happens either in my firmware or in the official fork and then I will be able to solve it.
I assume that pitch is moving when you tilt the whole tracker (keeping the 45 degree angle relative to ground)? Do you use classic closed-loop servos or continuous rotation ones?
-
68
-
69
-
70
-
71
-
72
of 113 Next