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Applying RC staff to robotics

PostPosted: Sat Nov 05, 2011 7:37 pm
by hrizzi
Hi there,

I just registered, my name is Hernan Rizzi and I live in Argentina. Looking around for some stuff to start building RC robots got to this place, and got a lot of great information so far. But I do need a little more of help and hence this post...

I plan to build a series of RC robots (no-brain robots) as a hobby project with my kids. I did that in the past when I was younger (way un the past) and had a lot of fun at it, but I esentially paired up a lot of pieces from broken toys. I intend to make my life easier now, and produce better robots, so I started to look at the RC ecosystem to get supplies.

I pretty much made my mind in terms of Rx/Tx, I'll get the Turnigy 9x - may be an overkill initially but hopefully will be enough for a few years. I'll be using mostly digital servos for the movements, and DC geared motors for the wheels and other movements with more torque requirements.

But now I need to get the signals from the receiver to actually cause any movements in the servos and/or motors, and there I'm lost. I mean, I'm amateur radio so I have a little knowledge about electronics, but I get lost on what pieces should I buy. For example, what's an ESC? it's simply a way to amplify the power getting out the receiver to the motor so you can drive more speed/torque there?

Whats an SBEC? UBEC? PCM? PPM? how should I read those specs to tie all them together? I guess what I'm looking for is a kind of technical glossary, I've looking around but haven't been able to find one yet, and since this site has great detailed articles I thought I would ask for recommendatios for where to continue my reading.

Thx in advance,
GHR

Re: Applying RC staff to robotics

PostPosted: Sat Nov 05, 2011 11:15 pm
by ergocentric
robonova.de is a division of Hitec, an RC manufacturer

Image

Then there is lego mindstorms

http://tiltedtwister.com/robots.html

http://www.youtube.com/watch?v=w3f-WyDqOUw

There are a couple of places that sell accessories to help build robots on standard and modified servos

Re: Applying RC staff to robotics

PostPosted: Sun Nov 06, 2011 9:52 am
by BillGriffiths100
Hi Hernan,
Just to get you started an ESC is an electronic speed controller.
The brush-less escs we use for electric flight drive a sort of stepper motor which uses no brushes and the controller senses the position of the rotor by inductive feedback and activates the driver coils accordingly.
The older type of esc supplied pulses of voltage /current of varying width to a DC motor which used brushes.
A SBEC is a switching battery elimination circuit this is better than a UBEC which is an ultra battery elimination circuit which uses paralleled linear regulators (when one goes the others follow).
Ubecs / Becs are built into a lot of brushless speed controllers but they can fail and take out the vehicle and the rest of the esc circuitry.
They get hot and being a linear regulator they dissipate the voltage drop as heat, the more batteries / higher voltage you use the worse the problem. Use a separate SBEC if possible for your radio and servos.
PCM is a method of data transmission in which the information for each servo is sent as a digital word to the receiver which then converts it to a pulse of variable length usually between 1 and 2 milliseconds with a bit of variation at the end for trim for the servos.
PPM is a system whereby the pulses for the servo are transmitted directly as frequency shift pulse widths (FM), and the receiver decodes them for the servos, in an older system the information was sent amplitude modulation (AM).
Bruce has a good tutorial about how information is sent on the frequency hopping new 2.4GH gear which is on this website or his u-tube channel. http://www.youtube.com/user/RCModelRevi ... ZGcyuezMik
The Sparkfun website in the US has a lot of control boards etc.
Rgds,
Bill