Saturday, March 8, 2008

Re: [oopic] Quadrature Encoder

Well, I have now counted the actual revolutions, and I will rarely get counts
lower than 1 rps, and the top speed will be 3-5 times that. This means that
pulse count will occasionally be below 1 kHz, but will generally be in the
1.5-3KHz.

I also heard that in other peoples experience, wheel slippage will cause
sufficient errors that simply counting wheel revolutions is a dubious
measure to begin with. My alternatives seem to be these:

1) Possibly use oCounterH to count a single wheel speed (only 1 IO line for
this object).
2) Just measure true ground speed the old fashioned way and make up a speed
curve based on the set motor speed.

Frankly, unless there is something I have missed, I'm inclined to just use
option 2, since I have already implemented code that will be checking the
dead reckoning position against sonar echoes. Is there anything else I might
consider?

Shaggy wrote:
>
> Then I'll live with it.
>
> ooPIC Tech Support wrote:
>>
>> It is unchangeable, its part of the object.
>>
>> DLC
>>
>> Shaggy wrote:
>>> I had skipped right over the oQencode object. That alone makes things
>>> somewhat easier, but it appears that I will exceed the max frequency at
>>> full
>>> speed.
>>>
>>> However, the oQencode object appears to use the oCounterL object for
>>> counting, which counts a lower frequency signal. Is this true, and is it
>>> unchangeable?
>>>
>>>
>>>
>>>
>>>>Here is some sample odometry code for an optical encoder and a 'bot
>>>>with servo motors:
>>>>http://www.nubotics.com/support/ww01/code/oopic/ww01_oopic2p_square.osc.php
>>>>
>>>>My suspicion is that the servos drive right to the limit of the OOPic
>>>>capability.
>>>>
>>>>High speed counting using oCounter2H is limited to a single IOLine : #
>>>>16. Not very useful in this application...
>>>>
>>>>Richard
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>> --
>> ------------------------------------------------------
>> Dennis Clark ooPIC Tech Support
>> www.oopic.com
>> ------------------------------------------------------
>>
>>
>
>

--
View this message in context: http://www.nabble.com/Quadrature-Encoder-tp13322047p15919997.html
Sent from the OOPic mailing list archive at Nabble.com.


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