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.

Views: 64342

Reply to This

Replies to This Discussion

Pixhawks are very reasonable these days. ebay has then for less than $60 with free shipping. I have one if the latest V2.4.8 and have flown it all summer with no problems. APM is very old hardware technology. I upgraded everything a couple of years back.

Developers just don't have time to continue supporting such old hardware.

.

Well for some reason the developers seems to keep supporting APM on plane. We are talking about a tracker here, is the firmware that advanced it needs pixhawk? I am puzzled.  It's not a multi-rotor that needs more advanced navigation. Well I guess I am stuck having to fork out $60. It all adds up when and you get nickel-and-dimed building this stuff. 

Hi Patrick,

I agree with you that EKF to point two servos to a predefined spatial 3D coordinate is not required at all. I suspect that EKF is the cause for the pointing large deviations I noticed because EKF transforms real sensed data into future projections. However we do not need to do that for coordinates : they are what they are and should not be filetred in any way.

EKF is probably also the cause of the tracking lag we observe as it requires a time delay to compute.

But I am no developper and we'd better let developpers explain why they chose to use EKF for antenna tracker ?
 
Patrick Duffy said:

Well for some reason the developers seems to keep supporting APM on plane. We are talking about a tracker here, is the firmware that advanced it needs pixhawk? I am puzzled.  It's not a multi-rotor that needs more advanced navigation. Well I guess I am stuck having to fork out $60. It all adds up when and you get nickel-and-dimed building this stuff. 

I can confirm the deviations in tracking, as well as delays, as well as pointing correctly if the plane moves from right to left and a big deviation when the plane moves from left to right. It makes it almost useless. Sorry to be so critical, but that is the reality.

Before the introduction of Mavlink2, I was using Jakub Oller's firmware. It was flawless. Unfortunately, with Mavlink2, there were problems.

I also feel it is over engineered. I'm not a software engineer, but I totally agree with Hugues. EKF is probably not needed, neither other bells and whistles.

For me, it should have like an auto tune function, be able to work with 360 degrees servos and point to the plane. Simple and straight forward.

All we need now is find a developper in this community who is able (=question of time and skills. Randy is, as far as i know, the only dev who worked lately on the antenna tracker firmware but he's obviously busy on other things) to take the antenna tracker code re-engineering in hand to build this simple and straightforward tracker. I'm unfortunately not a developer but could assist in the functional analysis and requirements definition to help guide the development.

OK guys, so reading you comments I come to the conclusion that v1.0 is not good to use??

I recently replaced my 3kg servos, which were using relative good on some old version... around 0.74 for instance?!?

I installed 20kg servos... but I cannot get them to move properly! When testing all moves well, but when it has to track... there is a considerable delay in the reaction, and even when it starts moving it is constantly shaking left and right (for pan), and up and down (for tilt). I played around with the params but was unable to fine a setting that would stop this behaviour and would make it work properly! At least the old servos with the old firmware moved and tracked very well... and these right now are almost worthless.

Would going back to an earlier version of the firmware improve things? Preferably one where the EKF is not used?

Will the next version be out any time soon?

Nikola,

Version 0.8.0 firmware is working very well for me when ALT_SOURCE is set for GPS. You can still select version 0.8.0 by pressing the "Pick previous firmware" link in the Install Firmware section of Mission Planner. It works well for both copter and plane.

I have not tried version 1.0 yet...

Thank you, will give it a try! Any suggestion how to tune shaking servos just in case I keep having that issue?


Greg Covey said:

Nikola,

Version 0.8.0 firmware is working very well for me when ALT_SOURCE is set for GPS. You can still select version 0.8.0 by pressing the "Pick previous firmware" link in the Install Firmware section of Mission Planner. It works well for both copter and plane.

I have not tried version 1.0 yet...

Nikola,

Others have reported oscillations with v1.0 firmware so hopefully you will not see them in v0.8. A few pages back, Randy posted the differences added to v1.0. Maybe you can check out his blog entry. I copied his post below.

Reply by Randy on July 28, 2016 at 5:24am

You may have seen that I've done a blog post about Tracker version 1.0.  Basically this is 0.8 but it's got three improvements including the tilt compensation and PITCH_MIN and PITCH_MAX parameters replace the PITCH_RANGE parameter.  Version 1.0 is available through the Mission Planner's Beta firmwares link and if people think it's ok, I'll make it the official version next week some time.

Hi buddy i see your using Immersion Circular Polarized patch antenna any good ?


Greg Covey said:

I tested the new v0.8.0 of the APM Antenna Tracker which included a new filter to smooth input to the controllers. It worked great for both APM Copter v3.3.3 and APM Plane v3.2.3. My ALT_SOURCE parameter was set to use GPS.

My tracker uses an EZTracker with extra side car from ReadyMadeRC, a long range RDF900 telemetry unit and an ImmersionRC DUO 5.8GHz receiver with a directional and omni antenna. The extra side car acts as a counter-balance and a spare battery holder.

I posted my param file for those that are interested...

APM Antenna Tracker v0.8.0 from Gregory Covey on Vimeo.

Greg,

Using latest version of MissionPlanner I can't find this FW 0.8.0 in combobox when clicking on "Pick prev firmware" button.

The only AT FW I can see here is 0.7.6 and 0.7.3. Can you please send me hex file with AT 0.8.0?



Greg Covey said:

Nikola,

Version 0.8.0 firmware is working very well for me when ALT_SOURCE is set for GPS. You can still select version 0.8.0 by pressing the "Pick previous firmware" link in the Install Firmware section of Mission Planner. It works well for both copter and plane.

I have not tried version 1.0 yet...

Reply to Discussion

RSS

Groups

Season Two of the Trust Time Trial (T3) Contest 
A list of all T3 contests is here. The current round, the Vertical Horizontal one, is here

© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service