Author Topic: First time post, probably very 'newbie' question - rotational questions  (Read 1352 times)

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Offline mwillia4Topic starter

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I by no means consider myself nothing more than a tinkerer and hobbyist at the most.

I did have a question around some mechanics on how to contend with power and signals connections on rotational components.

My basic question is how to power and provide signals to electrical components on a platform that has a full 360 degree of rotation.  (think along the concept of a tank turret).

My initial thought was to have tracked platform which would contain the batteries, elctronics.  My question comes, how do power and signal the items on top of the platform.

I understand if I had limited range of movement I could cable along the arm/turret and not worry about it.  However I'd like to solve for continous rotation in in either direction.

So how would you power and signal items along a continous rotating platform?  I really hope my question is clear.  Thanks in advance.
« Last Edit: February 03, 2010, 11:49:07 AM by mwillia4 »

Offline Razor Concepts

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Re: First time post, probably very 'newbie' question - rotational questions
« Reply #1 on: February 03, 2010, 12:01:35 PM »
A metal ring and brushes  on the other part would work, but may be very noisy (think those old school slot cars with brushes on the bottom and the metal tracks)

Offline little-c

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Re: First time post, probably very 'newbie' question - rotational questions
« Reply #2 on: February 03, 2010, 01:47:32 PM »
you can use wireless transmittion and a seperate power supply. note, deffinition of wireless transmition is pretty large.
anything from IR transmition
(robot tutorials, http://www.societyofrobots.com/schematics_infraredemitdet.shtml)

to zigbee(lowest power requiremnets for easly avalible wireless units) or bluetooth transmition.


Offline gamefreak

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Re: First time post, probably very 'newbie' question - rotational questions
« Reply #3 on: February 03, 2010, 02:08:43 PM »
There was a post a while back on hackaday about a POV globe, Link
He routed the power through a headphone jack in order to get it where it need to go.
Would something like that work for your project?
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Offline mwillia4Topic starter

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Re: First time post, probably very 'newbie' question - rotational questions
« Reply #4 on: February 03, 2010, 03:14:24 PM »
GameFreak - I did think about this option, with a headphone jack, but was wondering about the lifespan.  Very similiar solution to Razor Concepts thoughts too.

Little-c - this was actually the path I was considering, was interested to see what others had came up against too.

I've actually seen a few possible solutions http://www.wirelinetech.com/rotary-connector.php http://www.mercotac.com/html/fourconductor.htmlbut not sure on pricing.

In doing some more searching (thanks to Razor Concepts key words) I came across this site http://www.keyocn.com/index.html  Seemed to be pretty much in line with what I was 'expecting'... simple search on ebay, some of these units are in the sub $20 range.

Thank you again to everyone!


Offline Soeren

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Re: First time post, probably very 'newbie' question - rotational questions
« Reply #5 on: February 03, 2010, 04:24:09 PM »
Hi,

Using slip rings IS the way to go and you have several options:
- Buy real industrial slip rings (expensive).
- Use a 1/4" jack plug with home made brushes (might wear down faster than anything else, as they're usually made from soft copper with a nickel plating and once the hard plating is worn out, the copper will soon follow.
- Make your own from the ground up from pieces of copper or brass tubing mounted on a (rigid) plastic tube and run the wires inside the tube - then make the brushes from bronze.

Power lines should have a capacitor connected to smooth out brown outs and signal lines would be helped with small caps calculated for the frequency and waveform, but a carefully worked out protocol could handle most of the possible noise - use a light dab of grease between slip rings and brushes to keep it from oxidizing.

For the signals, you could modulate them onto a carrier wave and have them capacitively connected to the rotating turret as well. with such a frictionless setup, it doesn't matter how far from the center of rotation the cap. coupled rings run, but with brushes there's friction, so keeping it close to the center will minimize the drag.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline MangoBot

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Re: First time post, probably very 'newbie' question - rotational questions
« Reply #6 on: February 03, 2010, 09:16:04 PM »
the electronics could be on a rotating platform and vertically above it would be a rod connecting it, as the arm spinned so would the whole electronics board,it would be like a merry-go-round(kinda)

Offline nottoooily

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Re: First time post, probably very 'newbie' question - rotational questions
« Reply #7 on: February 03, 2010, 10:30:15 PM »
Couple of ideas I started to develop once:

Inductive coupling. Basically just a transformer, use high freq. for power.

Brushes made from stranded wire in a V-groove. As well as being easy, this gives a lot of independent contact points. The wires or the groove can wear without much drama. There's a patent on this somewhere.



My basic question is how to power and provide signals to electrical components on a platform that has a full 360 degree of rotation.  (think along the concept of a tank turret).

Offline Admin

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Re: First time post, probably very 'newbie' question - rotational questions
« Reply #8 on: February 17, 2010, 06:32:09 AM »
When I was testing gyros, I needed to transmit serial data while the gyro was spinning. Probably not very elegant, but transmitting data by bluetooth was very easy and effective.

Gyro Calibration with Axon Microcontroller

 


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