FunJet

[Captain Future]

Hi Tom,
Do you know what would make the Gluonpilot more perfect?
An antenna tracker! That would be a very fine thing. Have you thought about, or is difficult to realize?
With paparazzi that's possible.

And one more question:
I want to build a catapult launch. Would the GP survive an automatic catapult launch, or the rapid acceleration would cause problems? Has anyone tried this before?

Best regards
Eddi

[lukasz]

Hi Eddi,

I was already talking with Tom on the tracking antenna system.
Personally I see three options:
1. If you are using extension board with OSD than you could have GPS coordinates sent in teletext via Video link. On ground this would be decoded and servos would move the tracking antenna.
2. If you use telemetry link (xbee) than on ground you would need some kind of servo controller that would be controlled via GCS software. I think this should work out: https://www.sparkfun.com/products/9664
3. RC system that has such implementation already in place I have RC solution that can be used as an RC link and tracking antenna at once.

If I would be a user that doesn't have solution 3 I would personally go with option 1.
Main plus of that is that you don't require laptop. On the second hand you need some kind of HW that will decode teletext and control tracking antenna - I think remzibi OSD uses such solution

As for the catapult. Maybe this is the matter of firmware but I had couple of times a situation when I throw the plane really fast in AP mode and instead of climbing it hit the ground. Probably because quick acceleration working on ACC. Tom is aware of that. So for catapult I guess some software work would be required to compensate that acceleration.

[Tom]

Hello all,

Antenna tracking should not be hard to implement (as Lukasz suggests), but I don't know what hardware I should support. I can't change the code for every individual who has another type of tracker

About the catapult launch, that would require 2 things:
- automatically start throttle when a large acceleration has been detected
- ignore heavy accelerations (already implemented but more test data needed)

As lukasz says we absolutely need to avoid the plane pitching down due to the large accelerations. This can be tested by doing to autolaunch in manual mode and look at the datalog how the pitch angle is calculated.

So basically someone needs to be the guinea pig and give us some data

[Captain Future]

Hi Lukasz,

The antenna tracker by paparazzi based on your second option and use the same servo controller.
That makes sense. The GCS knows exactly the position of the aircraft. The antenna will positioned in the home point, and aligned in one definite cardinal direction. From the position, height, and distance calculated the GSC the location and controls the servo. That's the theory, but unfortunately I'm not able to program it.

That with the catapult i have feared. Would be very bad, because my next Airframe is hard to start from the hand. To fix the problem for me is more important than the tracker.

Eddi

[Captain Future]

Hello all,

Antenna tracking should not be hard to implement (as Lukasz suggests), but I don't know what hardware I should support. I can't change the code for every individual who has another type of tracker

About the catapult launch, that would require 2 things:
- automatically start throttle when a large acceleration has been detected
- ignore heavy accelerations (already implemented but more test data needed)

As lukasz says we absolutely need to avoid the plane pitching down due to the large accelerations. This can be tested by doing to autolaunch in manual mode and look at the datalog how the pitch angle is calculated.

So basically someone needs to be the guinea pig and give us some data

Hi Tom,

You need only develop a solution, and then market them.
I would buy immediately.

@"automatically start throttle when a large acceleration has been detected"
Just as I had imagined. When the GP reach a speed of 3-5 m/s, go the autopilot from "man" to "auto". Just as it makes paparazzi.
Either way I'm going to build a catapult. I ordered the parts already. It will 4m long and is a masterpiece of precision engineering. I'll report back.

Eddi

[penguin]

Hi Eddi,

something like this?


my first and just simple one antenna tracker:


and the last one with auto calibration and auto alignment, just put down, switch on and wait for ok:


LCD with all necessary informations (where the plane is):


magnetic angle encoder instead conventional potis (with endless rotation):


My tracker only reached prototype status, but would be worth to be reactivated

Rainer

[lukasz]

Nice prototype Eddi
It looks quite complex.
For what do you need the accelerometer in the tracking antenna?

As for option 2 (tracking antenna based on xbee telemetry).
Here is something that generally has all we would need:
http://store.diydrones.com/ArduStation_p/de-0001-01.htm

Still I'm looking for some kind of cheep hardware that could read teletext and decode GPS position sent over video link. I have a feeling that this would be the best approach as not all people see a need of carrying a modem in their platform. I think FPV flyers are looking for a simple solution without the need of carrying a laptop to the field.
Anyway, either way is good. Also I think that Gluonpilot should stick to one technology/standard and not support all possible tracking antenna solutions.

[penguin]

Hi Lukasz,

I'm Rainer, not Eddi
The tracker works full-automatic that means it:
- measures platform angles and brings the platform in the horizontal position.
- measures and calibrates the compass orientation
- has own gps for position determination

Rotation axis works endless and telemetrie is done using Wi.232
Additional Video-Tx diversity using analog switch and RSSI-signal evaluation

Perhaps this could be a solution (audio subcarrier):
http://rc-cam.info/viewtopic.php?t=1879 ... sc&start=0
http://www.rcgroups.com/forums/showthread.php?t=1238316
http://www.kh-gps.de/dtmf.htm
http://www.kh-gps.de/bpsk.htm (BinaryPhaseShiftKeying)

Which RC are you using? Perhaps we could get the data to the ground using telemetrie downlink from RC?
(I'm just working on it)

Rainer

[lukasz]

Sorry Rainer for mixing your name

Yes, I was also looking at audio based telemetry. Although I still think teletext is better as some might use audio link just for audio

What regards to RC link. I use an RC link that is called eLeReS and is developed here in Poland.
Originally it was build basing on OpenLRS project but it ended up with totally re-written firmware.
Still the modules are compatible with OpenLRS. This system operates at 435,000 MHz (100mW)

Here are some key features:
- Same modules are used as TX, RX or Tracking Antenna - each can be programed to whether you want
- RX can either output 9 PWM signals or 1 PPM signal or S-BUS
- Telemetry - both modules have RS232 so you can send data from RX back to TX (currently guys are working on an up-link)
- Both RX and TX can measure BAT Level. If connected to RX than on ground you receive BAT voltage level for which you can set alarms.
- RX outputs RSSI level + via telemetry link you receive a copy of that to your TX - you can set audio warnings in case you are flying out of range.
- locator - in case you loose your plane you can turn on a locator. RX after signal lost goes to a locator after set time. Your TX is used to find your plane - you have audio signals that increase the closer you are to your plane.
- There is an option to attach an LCD that displays your plane parameters (RSSI, BAT Level, if GPS connected than GPS position)
- option to bind more than one RX to one TX
- other fancy features.

Generally this solution is available from this year. The guys are working on publishing this info on RCG.
Currently the modules can be bought here:
http://cyberdrones.com/shop/product.php?id_product=17

Tracking Antenna is something that is available from the past 2 months. People are testing this solution.
To be honest for that you don't need any gyroscopes or ACC. You just need one eLeReS module that receives data from the plane and positions the antenna accordingly.
Calibration of such setup is required only once - to define servo movement range.
Before power on you just need to orient the antenna north, power on your plane and antenna and once fix is found this position is saved as home. From now all tracking antenna calculations are done by eLeReS module based on sent GPS data from RX.

[penguin]

Although I still think teletext is better as some might use audio link just for audio

Yes, of course, I heard of people who love wind noise and motor sound in stereo instead of mono and sharing one channel
My Video Tx/Rx are all stereo, but I never was a friend of this solution...

I use an RC link that is called eLeReS and is developed here in Poland.

OpenLSR sounds very interesting...
- eLeSeR doku/blog is only in Polish?
- why did the Polish guys made their own one (and didn't use OpenLSR instead)
- Is it opensource?
- you ment telemetrie via UART, not RS232? Is it possible to connect any additional controller and use the Rx and Tx as Transceiver with implementation of own communication protocol, data, sensor or what ever?

To be honest for that you don't need any gyroscopes or ACC.

I have never claimed otherwise In that case you have to align your tracker manually. He must be aligned vertically (or horizontally) and the direction must be calibrated (north, south or any fixed direction). If you want to use only one GPS you can use the planes one and transmit the GPS position to tracker by pressing a key, for example. In your case servo movement range is an other part and is only done once. The angle/servo_movement is adjustment with the software/parameters. My tracker isn't driven by servos.

I can put down my tracker inclined up to 35°, only switch it on and wait for 'ready beep' or 'ready message' - thats it! If I would upgrade the firmware (too little time to prog and test that), I could mount my tracker on a car and follow the plane (or vice versa) without hardware changes. That was the original plan some years ago