figuring out the Antenna Tracker

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.

Hi !

I had some hard hours these days trying to get my antenna tracker up and running.
Although there are some minor issues it finally seems to do what it should do now!

I'm trying to describe the issues and questions I had to deal with and hope I can help someone with my solutions.
(I know most of the issues where discussed before but I think some kind of summary wont hurt and please... forgive my English)

But first at all some words to my setup:

Mechanical Hardware: -> 3D printed , inspired by eFPV Antenna Tracker, 2x continues rotating servos (on/off servos powered separately ), "slipring"
Electronics: 5v UBEC; APM 2.5; 3DR 433MHz radio (on telem1 connecting to my quadcopter), CZ-HC-05 Bluetooth module (on serial 2 connecting to my laptop), NEO-7M GPS module, RC832 Video receiver and hex antenna

My issues (chronological order):

1) The "Test" Buttons in Mission Planner are not working
2) The "Proxy Mode" drop down in Mission Planner does not work
3) How does the manual mode work?
4) No connection to the antenna tracker over the bluetooth module
5) No servo movement or tracking behaviour
6) No connection to my quadcopter when AT is connected over USB
--- not fixed yet
7) The AT is heavily wobbling back and forth while tracking
8) Antenna Tracker states that there is "NO GPS" when connected over bluetooth. But Mission Planner shows the correct position of my tracker (when moving around with it)
9) The YAW,ROLL and PICH values are not updated while connected through the AT.

-------------------------------------------------------------------------------------

My solutions:

1) The "Test" Buttons in Mission Planner are not working

Simple answer: This feature is not implemented yet.
Randy has an implementation in one of his branches (https://github.com/rmackay9/rmackay9-ardupilot/tree/antenna-wip6) but it's AT version 0.2 and it's not working correctly.
I've opened this github-issue https://github.com/diydrones/ardupilot/issues/1934 and randy promissed to implement the feature. For the meantime i've done it on my own. It's the original v0.4 with just the test feature added.
I've attached the pre-compiled APM hex.

2) The "Proxy Mode" drop-down in Mission Planner does not work

This feature has been removed from AT and has been replaced with a better mavlink routing. VEHICLE <-> AT <-> MISSION PLANNER. In Mission Planner you can use STRG+X to switch between vehicle and AT data.
I've opened the github-issue: https://github.com/diydrones/MissionPlanner/issues/811 and asked to remove the drop-down cause it's no longer neede.

3) How does the manual mode work?
It's meant to control yaw and pitch through your rc transmitter. It simply reads the inputs of RC1 and RC2 and uses its values to control the servos. So you would have to have a seperate rc reciever attached to your AT.
Maybe you could also use a joystick in Mission Planner but I haven't tried this

4) No connection to the antenna tracker over the bluetooth module

(This solution isn't related to the AT code but might be helpful)
I've connected the "CZ-HC-05" bluetooth module on serial 2. Windows (8.1) sees the module and binds to it (default PIN: 1234). Afterwards to virtual COM Ports got created. One is called "incoming" and the other one "outgoing" (hope that's right cause I use a German windows ;-))
Unfortunately I couldn't get any connection through one of these ports with any baudrate.
The solution was rather simple: The default baudrate in AT for "serial 2" is set to 57600. The default baudrate of my bluetooth module is 9600. I simply had to change the baudrate of the module and voila! How to do this for my specific module (CZ-HC-05) can be found here: http://hackaday.com/2013/09/04/modifying-the-hc-05-bluetooth-module...
Ah yes: in Mission Planner you have to user the virtual COM port called "outgoing" and the correct baudrate.

5) No servo movement or tracking behaviour

My quadcopter had a 3D fix, the AT was up and running, the LEDs on my 3DR radio where flashing like crazy (so there should be a connection between AT and quadcopter) but there was no servo movement at all.
The reason for this is that the AT is waiting for correct location info from the vehicle. But the vehicle wants to get "asked" for the info and the unkind AT doesn't ask for it.
So you have to set the SR_0(1) (depends where your 3DR radio is connected to) parameters of your vehicle to something between 2 and 5. So your vehicle will talk about its location info from start up and the AT starts to aim at the specified position.

6) No connection to my quadcopter when AT is connected over USB

When I connect the AT through the USB port I lose the connection to my quadcopter. As I said before I've connected my 3DR radion to the standard telemetry port of my APM. On APM boards the telem. port doesn't work when connected through USB. That's why I lost the connection to my vehicle.
(You can also see it on the LEDs of the 3DR radio).
I would recommend to user "serial 2" for the 3DR radio and the telemtry port for the bluetooth module. In this constellation the 3DR radio is always working and you don't need the bluetooth when connected through USB.

## Not solved yet

7) The AT is heavily wobbling back and forth while tracking

I'm using "continues rotating servos". These servos have a little potentiometer to adjust there trim value. In Mission Planner I've set the value for the middle (not moving) value to 1500 and adjusted the "pots" of my servos to this value.
The strange thing is that this adjustment doesn't seem to be permanent. From time to time my servos simple loose there "middle trim" and doesn't stop at 1500 any more. So the AT drives in his desired position, stops the servo with the 1500 value, but the servo moves on an the AT has to switch back the whole time.
I than have to adjust the servos again and everything is fine for the next 2-3 power circles.
I've no idea if my servos are just crab or if there are some interference on the signal line of the servos. Maybe the potis get loose while moving??
Perhaps I'm gonna try to replace the potentiometers with 2 resistors so the "middle" value shouldn't change any more.

8) Antenna Tracker states that there is "NO GPS" when connected over bluetooth. But Mission Planner shows the correct position of my tracker (when moving around with it)
The Lat. and Lon. values gets correctly updated when connected through bluetooth but the GPS state says "NO GPS". When connected through USB everything seems to fine.
Maybe it's a power issue of my APM board. I've fried my 3,3V regulator and replaced it. I'm also experiencing power issues with my bluetooth module which i have to power cycle after connecting the battery.
At the moment I'm waiting for an "APM power module" maybe this solves it.

9) The YAW,ROLL and PICH values are not updated while connected through the AT.
Most of my vehicle data is display while connected through my AT but YAW, ROLL and PITCH doesn't get updated. So the HUD also doesn't show this values. (hight, battery a.s.o work perfectly).
Must be some issue with the new mavlink routing.

AntennaTracker.cpp.hex

2015-03-08 20.48.57.jpg

2015-03-08 20.48.34.jpg

Replies

- Mike Mac > Christian Thalhammer March 25, 2015 at 6:12am
  
  I recall reading that Telem1 is for OSC and does not provide VCC. You need to have a separate power source for anything on Telem1. Hopefully that should get you going.
  
  　
  
  .
  - Christian Thalhammer > Mike Mac March 25, 2015 at 6:31am
    
    Thanks for your replay but thats not the case.
    
    The Telem1 provides the uart rx,tx connections as well as vcc and gnd. There are several tutorials on how to connect peripheral devices to telem1. I'm going to take a deeper look at this but I'm afraid it might me some software issue.
    - Martin > Christian Thalhammer March 25, 2015 at 7:15am
      
      APM 2.x basically has one free serial, the other is reserved for USB communication. You would have to use Pixhawk to connect 2 radios.
      - Christian Thalhammer > Martin March 25, 2015 at 11:59pm
        
        We are talking about "Antenna Tracker" where UART2 (telem2) is prepared for a second radio (also on APM2.X boards). Having bluetooth und telem2 and 3DR radio on telem1 works like a charme on my APM 2.x. The problem is the other way around.
        
        The idea of switching the bluetooth module (connection to my laptop) to telem1 is to have an active mavlink connection to the vehicle (through uart 3dr on uart2) while beeing connect through usb. (bluetooth -> telem1 will be inactive while connected to usb as you said)
        
        3qs7z40lxxok2 > Christian Thalhammer April 1, 2015 at 5:58pm
        
        Hi all can we use mission planer to upload firmware to Apm 2.6 to use as antenna tracker
        
        or dio i have to compile it ?
        
        Keith G > 3qs7z40lxxok2 April 1, 2015 at 8:04pm
        
        You can load it from mission planner. Good luck getting it to work though. I can't get pitch to function and support isn't available.
        
        3qs7z40lxxok2 > Keith G April 2, 2015 at 12:58am
        
        well loaded firmware in mission planer plugged some servos in it power it on no go
        
        so went back reading this forum came across net id
        
        as soon as changed Net id of the quad works servos move..
        
        now to get the Bluetooth to work LoL
        
        3qs7z40lxxok2 > 3qs7z40lxxok2 April 8, 2015 at 4:19am
        
        it did work turn it off went in side for dinner now i cant get to work LoL
        
        got be some prams i am missing
        
        can someone post the tracker prams file
        
        Thanks
        
        Keith G > 3qs7z40lxxok2 April 5, 2015 at 3:44pm
        
        Did you get it working? I'm issues? If yes, how did you work them out?
Christian Thalhammer March 8, 2015 at 12:56pm

Hi !

I had some hard hours these days trying to get my antenna tracker up and running.
Although there are some minor issues it finally seems to do what it should do now!

I'm trying to describe the issues and questions I had to deal with and hope I can help someone with my solutions.
(I know most of the issues where discussed before but I think some kind of summary wont hurt and please... forgive my English)

But first at all some words to my setup:

Mechanical Hardware: -> 3D printed , inspired by eFPV Antenna Tracker, 2x continues rotating servos (on/off servos powered separately ), "slipring"
Electronics: 5v UBEC; APM 2.5; 3DR 433MHz radio (on telem1 connecting to my quadcopter), CZ-HC-05 Bluetooth module (on serial 2 connecting to my laptop), NEO-7M GPS module, RC832 Video receiver and hex antenna

My issues (chronological order):

1) The "Test" Buttons in Mission Planner are not working
2) The "Proxy Mode" drop down in Mission Planner does not work
3) How does the manual mode work?
4) No connection to the antenna tracker over the bluetooth module
5) No servo movement or tracking behaviour
6) No connection to my quadcopter when AT is connected over USB
--- not fixed yet
7) The AT is heavily wobbling back and forth while tracking
8) Antenna Tracker states that there is "NO GPS" when connected over bluetooth. But Mission Planner shows the correct position of my tracker (when moving around with it)
9) The YAW,ROLL and PICH values are not updated while connected through the AT.

-------------------------------------------------------------------------------------

My solutions:

1) The "Test" Buttons in Mission Planner are not working

Simple answer: This feature is not implemented yet.
Randy has an implementation in one of his branches (https://github.com/rmackay9/rmackay9-ardupilot/tree/antenna-wip6) but it's AT version 0.2 and it's not working correctly.
I've opened this github-issue https://github.com/diydrones/ardupilot/issues/1934 and randy promissed to implement the feature. For the meantime i've done it on my own. It's the original v0.4 with just the test feature added.
I've attached the pre-compiled APM hex.

2) The "Proxy Mode" drop-down in Mission Planner does not work

This feature has been removed from AT and has been replaced with a better mavlink routing. VEHICLE <-> AT <-> MISSION PLANNER. In Mission Planner you can use STRG+X to switch between vehicle and AT data.
I've opened the github-issue: https://github.com/diydrones/MissionPlanner/issues/811 and asked to remove the drop-down cause it's no longer neede.

3) How does the manual mode work?
It's meant to control yaw and pitch through your rc transmitter. It simply reads the inputs of RC1 and RC2 and uses its values to control the servos. So you would have to have a seperate rc reciever attached to your AT.
Maybe you could also use a joystick in Mission Planner but I haven't tried this

4) No connection to the antenna tracker over the bluetooth module

(This solution isn't related to the AT code but might be helpful)
I've connected the "CZ-HC-05" bluetooth module on serial 2. Windows (8.1) sees the module and binds to it (default PIN: 1234). Afterwards to virtual COM Ports got created. One is called "incoming" and the other one "outgoing" (hope that's right cause I use a German windows ;-))
Unfortunately I couldn't get any connection through one of these ports with any baudrate.
The solution was rather simple: The default baudrate in AT for "serial 2" is set to 57600. The default baudrate of my bluetooth module is 9600. I simply had to change the baudrate of the module and voila! How to do this for my specific module (CZ-HC-05) can be found here: http://hackaday.com/2013/09/04/modifying-the-hc-05-bluetooth-module...
Ah yes: in Mission Planner you have to user the virtual COM port called "outgoing" and the correct baudrate.

5) No servo movement or tracking behaviour

My quadcopter had a 3D fix, the AT was up and running, the LEDs on my 3DR radio where flashing like crazy (so there should be a connection between AT and quadcopter) but there was no servo movement at all.
The reason for this is that the AT is waiting for correct location info from the vehicle. But the vehicle wants to get "asked" for the info and the unkind AT doesn't ask for it.
So you have to set the SR_0(1) (depends where your 3DR radio is connected to) parameters of your vehicle to something between 2 and 5. So your vehicle will talk about its location info from start up and the AT starts to aim at the specified position.

6) No connection to my quadcopter when AT is connected over USB

When I connect the AT through the USB port I lose the connection to my quadcopter. As I said before I've connected my 3DR radion to the standard telemetry port of my APM. On APM boards the telem. port doesn't work when connected through USB. That's why I lost the connection to my vehicle.
(You can also see it on the LEDs of the 3DR radio).
I would recommend to user "serial 2" for the 3DR radio and the telemtry port for the bluetooth module. In this constellation the 3DR radio is always working and you don't need the bluetooth when connected through USB.

## Not solved yet

7) The AT is heavily wobbling back and forth while tracking

I'm using "continues rotating servos". These servos have a little potentiometer to adjust there trim value. In Mission Planner I've set the value for the middle (not moving) value to 1500 and adjusted the "pots" of my servos to this value.
The strange thing is that this adjustment doesn't seem to be permanent. From time to time my servos simple loose there "middle trim" and doesn't stop at 1500 any more. So the AT drives in his desired position, stops the servo with the 1500 value, but the servo moves on an the AT has to switch back the whole time.
I than have to adjust the servos again and everything is fine for the next 2-3 power circles.
I've no idea if my servos are just crab or if there are some interference on the signal line of the servos. Maybe the potis get loose while moving??
Perhaps I'm gonna try to replace the potentiometers with 2 resistors so the "middle" value shouldn't change any more.

8) Antenna Tracker states that there is "NO GPS" when connected over bluetooth. But Mission Planner shows the correct position of my tracker (when moving around with it)
The Lat. and Lon. values gets correctly updated when connected through bluetooth but the GPS state says "NO GPS". When connected through USB everything seems to fine.
Maybe it's a power issue of my APM board. I've fried my 3,3V regulator and replaced it. I'm also experiencing power issues with my bluetooth module which i have to power cycle after connecting the battery.
At the moment I'm waiting for an "APM power module" maybe this solves it.

9) The YAW,ROLL and PICH values are not updated while connected through the AT.
Most of my vehicle data is display while connected through my AT but YAW, ROLL and PITCH doesn't get updated. So the HUD also doesn't show this values. (hight, battery a.s.o work perfectly).
Must be some issue with the new mavlink routing.

AntennaTracker.cpp.hex

2015-03-08 20.48.57.jpg

2015-03-08 20.48.34.jpg

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figuring out the Antenna Tracker

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