[Noisebridge-discuss] Filling order for MA3 Miniature Absolute Magnetic Shaft (Rotary) Encoders

[Christie Dudley]

Dead reckoning relies on knowing exactly how far you've traveled and in what
direction.  It's my understanding that this is the feedback mechanism you
want if you expect to have any degree of precision on which direction you're
pointed and so forth.

I'm also thinking about looking into a completely different system and
figuring out relative location by a couple of different mechanism.


Christie

---
Fear is the mind-killer. Fear is the little-death that brings total
obliteration.
- Bene Gesserit Litany


On Tue, Apr 14, 2009 at 2:12 PM, Michael Shiloh <michaelshiloh1010 at gmail.com
> wrote:

> hey corey! nice to see you here!
>
> isn't dead reckoning flawed? or are you tolerant of these flaws?
>
> Corey McGuire wrote:
>
>> Hey all, new to the list but been to NB a dozen times.
>>
>> I am filling out an order for a project Christie and I are working on.
>>  The application we have is, we need position sensing for steering and dead
>> reckoning for robots.  There are a number of considerations and we've had a
>> tough time finding one thing that does it all:
>>
>>    * Absolute encoding
>>    * High Resolution (positions per revolution)
>>    * Cycles (many as low as 20,000 revolutions!)
>>    * Size
>>    * Pin-out (many encoders require up to 8 digital IO each)
>>    * Price
>>
>> But with the advice of the good Dr. Foote, we may have found what we need.
>>  It's almost too perfect!
>>
>> http://tr.im/abmag
>>
>>   1. It's got Absolute encoding
>>   2. It has 10bit or 12bit resolution.  Up to 4096 positions per
>>      revolution! (We were going to settle for 16!)
>>   3. Cycles are in the millions, depending on the load
>>   4. .3" in diameter
>>   5. 3 pins
>>   6. As low as $36 for single orders
>>
>> Ok, so these are 5 times as expensive as the encoders we were going to
>> use, but the cheap encoders meant we were either going to need serious
>> hardware to read all the data, or we were going to need an Arduino per
>> encoder.  They may still have been cheaper, but not when considering our
>> labors.
>>
>> There are two models I am interested in.  They are identical except that
>> one uses bushings and one uses ball bearings.  The ball bearing model has a
>> long life, can operate at higher speed, is less weight and may be smaller.
>>  The price difference starts at $6.
>>
>> If anyone else is interested in getting in on an
>>
>> MA3-P10-125-N
>>
>> Quantity        Price
>> 1       $36.00
>> 10      $31.54
>> 50      $27.78
>> 100     $23.89
>> Over 100        Call for quote
>>
>>
>> MA3-P10-125-B
>>
>> Quantity        Price
>> 1       $41.80
>> 10      $37.34
>> 50      $33.58
>> 100     $29.69
>> Over 100        Call for quote
>>
>>
>> We are interested in getting a bulk order in, not just to lower price, but
>> because we thought others might be interested, and the more interested
>> people we have, the more brains we have to pick should there be problems.
>>
>> What say ya'll?
>>
>> Ciao!
>>
>> --
>> Success is a tasty spirit distilled from bitter failure
>> --Coreyfro
>>
>>
>> ------------------------------------------------------------------------
>>
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