12-04-2012 10:24 PM

kenavt

Re: paper: Team 2410 Swerve Drive Project

I have heard of "continuous turn" potentiometers, that theoretically can turn indefinitely (with a set range of values that reset every 360 degrees or so). I don't have any experience with them - I'm hoping somebody will post who has - but these could potentially enable multiple revolutions per pod, as encoders would.

12-04-2012 10:27 PM

MichaelBick

Re: paper: Team 2410 Swerve Drive Project

Quote:

Originally Posted by kenavt I have heard of "continuous turn" potentiometers, that theoretically can turn indefinitely (with a set range of values that reset every 360 degrees or so). I don't have any experience with them - I'm hoping somebody will post who has - but these could potentially enable multiple revolutions per pod, as encoders would.

12-04-2012 10:37 PM

Ether

Re: paper: Team 2410 Swerve Drive Project

Quote:

Originally Posted by MICHAELABICK These are called magnetic encoders: http://www.usdigital.com/products/en...tary/shaft/MA3

12-04-2012 10:44 PM

Nuttyman54

Re: paper: Team 2410 Swerve Drive Project

There are several types of sensors that can be used

1) Incremental encoders: give pulses to say they've moved some part of a rotation. Quadrature encoders can tell which direction, pulsed encoders give a special pulse every revolution

2) Absolute encoders: these come in two common varieties, optical and magnetic (as Michael pointed out above). These are the most commonly used in FRC application that require infinite angular sensing

3) Infinite rotation potentiometers: quite simply these are pots that have no hard stops. They do exist, but they're usually not very good for this type of application because tend to have a dead-band.

12-04-2012 10:50 PM

MichaelBick

Re: paper: Team 2410 Swerve Drive Project

Quote:

Originally Posted by Ether Absolute encoders can be magnetic or optical. All the optical encoders in the KoP are incremental.

12-04-2012 11:05 PM

Ether

Re: paper: Team 2410 Swerve Drive Project

Quote:

Originally Posted by MICHAELABICK Correct. I forgot about that. What are the performance differences between the two?

12-04-2012 11:36 PM

Gdeaver

Re: paper: Team 2410 Swerve Drive Project

Last year we used BI 6127V1AL.5FS magnetic sensors. Go to Digikey and search for that part number. Notice the cost. Down load the data sheet for specifics.They out put an analog voltage that corresponds to the angle. The voltage varies from .25 volts to 4.75 volts. With all things considered this works out to about .5 degree resolution. This is more of a c-rio limitation. For higher resolution one would have to go to a serial (SPI) type sensor. CUI has a capacitive absolute angle sensor with 12 bit resolution. Look at the AMT series. Avago also has a serial solution. The Bi sensors worked fine for us. The Bi's have a bronze bushing so they cant take high rpm's or mis alignment. There are special couplers to protect sensors from misalignment. You may want to check first choice for an example.
http://www.digikey.com/product-detai...393-ND/2620662

12-05-2012 07:38 AM

DELurker

Re: paper: Team 2410 Swerve Drive Project

Quote:

Originally Posted by Gdeaver Last year we used BI 6127V1AL5FS magnetic sensors. Go to Digikey and search for that part number.

12-05-2012 07:44 AM

Gdeaver

Re: paper: Team 2410 Swerve Drive Project

Sorry I left out the " . " Link
http://www.digikey.com/product-detai...393-ND/2620662

12-07-2012 05:28 PM

Ether

Re: paper: Team 2410 Swerve Drive Project

Quote:

Originally Posted by CalTran Thread created automatically to discuss a document in CD-Media.

12-07-2012 06:52 PM

CalTran

Re: paper: Team 2410 Swerve Drive Project

No, sadly we got a bit behind when our teacher went to the Autodesk University conference in Vegas last week and we couldn't purchase materials. We should have the modules completed on Tuesday, hopefully.

12-15-2012 10:07 PM

Ether

Re: paper: Team 2410 Swerve Drive Project

Quote:

Originally Posted by CalTran We should have the modules completed on Tuesday, hopefully.

12-16-2012 03:42 PM

CalTran

Re: paper: Team 2410 Swerve Drive Project

Well, depends on your definition of good news. We've completed a module, and are working on the other 2-3 modules, depending on what material we can scrounge up for our rapidly ending off season. This prototype may continue on into regular season, with an "upgraded" swerve debuting on our robot at Greater Kansas City, game allowing of course. If the game does not allow for it, then we'll simply finish the prototype, slap it on to a base, and stick our 2012 robot sans-drive on top for a snazzy demo robot.

12-16-2012 04:04 PM

AdamHeard

Re: paper: Team 2410 Swerve Drive Project

Quote:

Originally Posted by CalTran Well, depends on your definition of good news. We've completed a module, and are working on the other 2-3 modules, depending on what material we can scrounge up for our rapidly ending off season. This prototype may continue on into regular season, with an "upgraded" swerve debuting on our robot at Greater Kansas City, game allowing of course. If the game does not allow for it, then we'll simply finish the prototype, slap it on to a base, and stick our 2012 robot sans-drive on top for a snazzy demo robot.