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Camera tilt and pan controlled by head tilt - done


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#21 mieczotronix

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Posted 05 July 2006 - 11:58 AM

I just had a quick look at the code - it seems to be synchronising itself on the TX's PPM output, and to change 3 of the channels before giving it to the PPM in again.

Exactly. This little project is actually three projects in one. It does I ever wanted to do with microcontrollers and servos: extends servo movements, processes the PPM stream and does the headtracking!
I also wonder whether using this technique I could turn my Optic 6 (5 proportional + 1 discrete channels) into 8 discrete channel machine. Just by replacing servo cycles I don't need with what's useful and by extending the 6-channel PPM train with two another servo pulses. I hope this will work since I don't believe the PPM signal that goes to the trainer port is subject to any further processing in the transmitter before it gets to the FM module.

And thanks Mr RC-CAM for the links! I'm quite new to this forum, so it will be a lot of reading for me

Edited by mieczotronix, 05 July 2006 - 12:00 PM.


#22 mieczotronix

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Posted 05 July 2006 - 12:08 PM

Unfortunately I haven't been able to do it because the user interface/configuration routine took so much code space I ran out of memory to add that feature... :(

maybe you should scale down and use a DIP-switch/jumper config interface. Why bother with menus and UI for stuff that's only done once.

#23 Kilrah

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Posted 05 July 2006 - 12:37 PM

That's the point, it's not only done once. Depending on the R/C TX, like with mine, I have to redo the configuration each time I change model...
For the settings I've implemented if everything was to be done with hardware switches and stuff I'd need like 12 dips and 2 pots... which would mean 14 extra input pins on the controller plus the actual controls, thus a ~3x bigger unit...
Compromises, as always ;)

#24 Temporary Insanity

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Posted 05 July 2006 - 12:38 PM

Hmmm... I wonder what I'd have if I hacked into Prikupits' schematic and dropped in a dual axis, analog output gyro?
It's temporary...really!

#25 Kilrah

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Posted 05 July 2006 - 01:11 PM

Something strange :lol:


The accelerometer gives out an information that can be directly treated as a position. With a gyro the first thing you'd have to do would be to integrate the rotational speed info it gives you to get that position (where the drift comes from :) )
Then, you would add a good differential amp between its reference terminals and its outputs, and hope your sensor is really symmetric ;)


Mmh, a post appeared on top of the page..
The Optic 6 hack might work. You should first ensure that there is no further processing as you say, for example by using a transmitter that has a 8-channel output and connecting it to the trainer port. Some TX's are pretty strict regarding the input signal and will automatically switch back to the master if looks too different from what's expected. The Futabas do accept a bit more throw than normal, so I've been able to boost the travel to about 150%. I still use a module in the aircraft to get the maximum mechanical servo throw though. They all transmit 8 channels.

Edited by Kilrah, 05 July 2006 - 01:18 PM.


#26 mieczotronix

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Posted 05 July 2006 - 01:30 PM

as for the gyro hack. I've also thought about that. Yet since I'm no good at electronics and wouldn't ever come up with the opamp circuit myself I wonder whether I could do w/o op amp and with just an a/d converter like in the accelerometer version. Will it be possible?
And the integration in this case would be simple addition of sampled gyro yaw signal at fixed sampling rate (taking into consideration signs/direction rotation), or do I miss something?

As for the 6 to 8 channel conversion. I'm just hoping that the only failsafe circuit preventing corrupted buddy signal from being aired from trainer's transmitter is trainer's finger sitting on the trainer switch. It is monostable for some reason. Maybe for this reason. I just hope Optic 6 firmware does not this signal check as it's quite simple transmitter.

Edited by mieczotronix, 05 July 2006 - 01:32 PM.


#27 Kilrah

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Posted 05 July 2006 - 02:14 PM

You could of course use separate A/D inputs to sample reference and output. That might need some software filtering then.
But an amplification is very likely to be needed. The output voltage change is usually very small. If I check the sensor I had used a couple of years ago, the scale factor is 0.67mV/deg/sec. That's less than 0.2V swing at full scale, when you'd want to use the most of your A/D's range for better precision. That requires a good analog circuit too, as less than 1mV error on the sensor's side will already cause a noticeable drift.
I'm not that good at analog design either, which is why I've abandoned my analog version before even having it working once I found a digital sensor...

#28 Prikupets

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Posted 11 July 2006 - 04:14 AM

Sorry, I missed whole discussion.
I added sort of low-pass filtering to the code and now servo are much more stable to jerky movements. I have to change S-Video-type connector for trainer cord to something more strong, i.e. COM or VGA port connector, because the cord is often falls out from the nest due its own weight.
Source, HEX code: here

#29 mieczotronix

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Posted 11 July 2006 - 05:08 AM

Great!
Could you post a video of how the new code works?

#30 Prikupets

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Posted 11 July 2006 - 07:26 AM

Not right now <_< I am going to install it to hat and try in real world. :blink:

#31 Vrflyer

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Posted 11 July 2006 - 08:46 PM

Not right now <_< I am going to install it to hat and try in real world. :blink:

That's great, tell us your result, we will be happy to know more.

#32 mieczotronix

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Posted 15 July 2006 - 02:49 AM

Could someone tell me what's the exact purpose of 10uH chokes on I/O lines of Pirkupet's original schematics? What are they there for? I guess to eliminate some kind of interference, but what kind of? Generated from engine or radio frequency? Or maybe for some impedance matching or sth? Do they serve the same purpose as ferrite rings on p/s lines or I should use ferrite rings as well?

#33 Prikupets

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Posted 15 July 2006 - 04:09 AM

Could someone tell me what's the exact purpose of 10uH chokes on I/O lines of Pirkupet's original schematics? What are they there for? I guess to eliminate some kind of interference, but what kind of? Generated from engine or radio frequency? Or maybe for some impedance matching or sth? Do they serve the same purpose as ferrite rings on p/s lines or I should use ferrite rings as well?

The chokes are needed for eliminating RF antenna signal in trainer cord. I have seen this solution in the Hitec Flash 5 circuit and did just same.

Here is the updated video with version 2.0 source (low pass filtering): http://forum.rcdesig...=attach&id=4274

#34 mieczotronix

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Posted 15 July 2006 - 07:00 AM

Thanks! I watched the video and now it really seems to work smoother.
BTW what kind of aircraft is your cam mounted on?

#35 Prikupets

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Posted 17 July 2006 - 12:50 AM

It's like a Kite Plane from Rogallo. Here is the link to my blog records regarding it:
http://forum.rcdesig...?showentry=1514,
http://forum.rcdesig...?showentry=1417,
http://forum.rcdesig...p?showentry=352,
http://forum.rcdesig...p?showentry=146
and to my blog itself: http://forum.rcdesig...upets/index.php?
Sorry, it is totally in Russian. Please ask me and I will translate some paragraphs for you ;)

#36 mieczotronix

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Posted 17 July 2006 - 01:28 AM

Thanks for the links

Sorry, it is totally in Russian. Please ask me and I will translate some paragraphs for you  ;)

That should not be a big problem since I studied Russian in primary and in high school. Although I haven't used it since that, I should still remember something

Quite an interresting craft this rogallo thingy. Is it kind of a slow-flyer?

BTW. I see we have the same googles. How do you find yours? Mine are somehow difficult to tune (either the picture is too contrasty/too dark or sth like that

Edited by mieczotronix, 17 July 2006 - 01:30 AM.


#37 Prikupets

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Posted 17 July 2006 - 02:15 AM

Yes, it's VERY slow. AUW is about 700g, but it's still fly as feather. Pretty difficult to fly in windy day (above 3 m/s).

Googles: same thing. I should constantly tune it, but I suppose it's because of poor camera.

#38 Kilrah

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Posted 17 July 2006 - 02:27 AM

Sorry, it is totally in Russian.

Indeed :wacko:

The only thing I've been able to read is a quote of one of my posts on here :lol:

Seems pretty interesting though. And yes, these goggles, especially the low resolution version, are pretty difficult to adjust, that's not due to the camera.

#39 mieczotronix

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Posted 06 January 2007 - 12:52 PM

just for the record
The same device Prikupets did on PIC I've managed to do on AVR Atiny2313 +ADXL213AE . I've been still working on it and tweaking things. I also ordered a cheap piezo gyro to see if it can be used to control camera pan (as with the current accelerometer-based setup to pan the camera you have to tillt your head sideways).
Some videos of early prototype on youtube:


#40 Terry

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Posted 07 January 2007 - 12:04 AM

Looks good :)
What is the duration of your rogallow wing plane ?
Do you have any info on your OSD in english ?

Terry