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Old Nov 09, 2011, 03:28 PM
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Matt Gunn's Avatar
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RS-232 to PWM for PTZ Cameras?

I'm trying to control a standard Pan-Tilt-Zoom (PTZ) camera from an rc transmitter.

The PTZ Im using is usually controlled through an RS-232 serial port, and I know there are a few commercial PWM convertors, but I have no idea how to control it with an rc transmitter.

Are there any commercially available serial to PWM units which would allow me to control one of these cameras from the servo ports of my r/c receiver?
thanks
Matt
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Old Nov 10, 2011, 02:14 PM
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how about ANY known method of controlling a PTZ camera setup?

UAV small businesses do it alot, Im wondering if they use a USB zigxbee and display it on a laptop? Any help would be appreciated.
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Old Nov 11, 2011, 09:02 AM
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Originally Posted by webdr View Post
how about ANY known method of controlling a PTZ camera setup?

UAV small businesses do it alot, Im wondering if they use a USB zigxbee and display it on a laptop? Any help would be appreciated.
They do not use proprietary PELCO systems to control their cameras. I don't know of anyone that has purchased an off-the-shelf PELCO PTZ camera for this purpose. The lag from the encoding/transmit/decoding/display chain for network cameras makes using them for flight completely useless.While there are a number of ways to do this the most common are servos that use PWM or stepper motors.

I build mine from scratch.
This one uses a cannibalized Servo City pan/tilt. Has 360 degree pan and 190 degree tilt.

Good Luck,

Rob
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Old Nov 11, 2011, 09:41 AM
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thanks for the information. I have a number of pan/tilts to mess with, and Im glad you steered me from the PTZ cam. Do you have a potentiometer on the tilt?
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Old Nov 11, 2011, 10:10 AM
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Originally Posted by webdr View Post
thanks for the information. I have a number of pan/tilts to mess with, and Im glad you steered me from the PTZ cam. Do you have a potentiometer on the tilt?
The tilt servo is standard with the exception that I added resistors in-line to the internal potentiometer to widen the range of movement without having to use TX programming.

I use multi-turn potentiometers and use gearing to get the range of movement I need. The pan on this one is using a 3 turn pot and geared to give 3X the position resolution that is available with standard servo potentiometers. With it moving 360 degrees that drops the advantage to 1.5x but still more precise than standard.

Have fun and good luck!

Rob

BTW, Fu at Foxtech FPV Systems has a nice RC controlled zoom camera too. It's a bit pricey and unfortunately it is PAL so not terribly useful for US users unless you have a system capable of handling recording PAL.
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Old Nov 11, 2011, 10:17 AM
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thanks again. I plan on incorporating a piclock 2x for gyro stabilization. All pan/tilt units Ive bought have the potentiometers already installed. Where can I purchase a pot?
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Old Nov 11, 2011, 10:57 AM
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Originally Posted by webdr View Post
thanks again. I plan on incorporating a piclock 2x for gyro stabilization. All pan/tilt units Ive bought have the potentiometers already installed. Where can I purchase a pot?
I get mine from Mouser and Digikey. The drill down menu for Digikey doesn't allow a direct link but search on potentiometers and look for number of turns. I use 3 to 10 turn depending on application.

Go for it!

Rob
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Old Nov 12, 2011, 08:04 PM
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Man!

You guys are like watching a couple of ants rubbing antennae together! You know they are communicating but you have NO IDEA what they are saying!



Gene
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Old Nov 13, 2011, 02:37 AM
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Originally Posted by CenTexFlyer View Post
Man!

You guys are like watching a couple of ants rubbing antennae together! You know they are communicating but you have NO IDEA what they are saying!



Gene
Why thank you sir! Gibberish is part of the package you get with your geek license.

And I will take this opportunity to say I am envious and very much admire the work you guys have done in this industry.

Have a Great Day,

Rob
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Old Nov 14, 2011, 05:31 AM
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Quote:
Originally Posted by webdr View Post
I'm trying to control a standard Pan-Tilt-Zoom (PTZ) camera from an rc transmitter.

The PTZ Im using is usually controlled through an RS-232 serial port, and I know there are a few commercial PWM convertors, but I have no idea how to control it with an rc transmitter.

Are there any commercially available serial to PWM units which would allow me to control one of these cameras from the servo ports of my r/c receiver?
thanks
Matt
I normally rip out the stock controller and install my own Arduino based one interfacing directly to the PTZ motors. Those RS-232 (more likely RS-485) controls can use a propriatary language for serial control and it isn't worth the effort to try and translate it then adapt it to PWM. At least IMHO.

Normally you'll find a geared DC Motor, and sometimes a stepper motor that actually handle the PTZ. I use drivers from Pololu or Sparkfun to interface these with an Arduino. The Arduino understands PWM from the RC Receiver. The potentiometers provide feedback. You write a little code to get all three to work together and you're done.

Servos as shown in the above picture are easiest, because they interface directly to the RC receiver -- but adapting servos to a commercial PTC mount is harder then simply replacing the controller.

My two cents.
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Old Nov 14, 2011, 11:53 AM
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Thanks for your reply chuck.

The part about writing a little code and your done is what get me

With regards to coding; I cant write my own but I can use existing and follow directions with success for the most part.

Can you help me identify what Arduino board and drivers I would need? Im on Sparkfun looking...
Matt
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Old Nov 15, 2011, 01:35 AM
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Maybe, maybe not.
If you take some pictures of the guts of your unit I'll try.
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Old Jan 15, 2012, 05:10 PM
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camship

Hi I'm making my own ptz as well ..finally found the chip I will use with the
atmel 8515 ..and now have my motor going reverse and forward ect..through 232. also I have ptz already and can get all the commands
it sends out through 485 so i can add the commands to the 8515 for 232..

but anyways ..curious on your setup ..you say you have 360 but by the picture it seems you can only reach 360 then have to go 360 back the other way to reach will say 1 or 361 hehe .. It is nice and i like the wood because most of mine will also be made out of wood .. just wondering what around the house could allow it to do continues 360.. .. I'm also going to hack up one of my camera's and attach zoom menu and focus
(canon fs100)
through the 8515 hopefully just a 4066 can handle that.... to limit wires I could attach another atmel 2313 and have the 8515 talk through that...or actually order a remote for my camera and just hook up ir to the 8515 prob be the best and fastest way ..seeing then i would not have to rip apart the camera .
either way I would need
to limit wire count because i think to get continues 360 we would need to use a track system with contacts rubbing ...


anyways nice job..and thanks for sharing.

Hopefully mine turns out that nice .. I know the circuit board i made
looks like crap, my laser printer crapped out so i was stuck drawing the board by hand and soic by hand is a pain..
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Old Jan 15, 2012, 09:07 PM
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How about a rotary connector?

http://www.mercotac.com/html/430.html
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Old Jan 16, 2012, 02:30 AM
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Bilox's Avatar
Melbourne, Australia
Joined Jul 2008
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I made a 3 X PWM to Pelco (485 Serial) converter and it works great!
It has full PTZ function.
I used and Arduino and sheild.

Cheers!
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