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Exploring encoder resolution further, given the limitations imposed by DIY toolkits - mine anyway. Printer resolution is an impediment to producing high resolution optical disks.
An alternative is a professionally made etched wheel - ideal. Alternatively, stuck with a printer, a double sided wheel, utilising reflective optics (in quadrature), with identical resolutions shifted a half phase out (if that's the right way of describing what I mean), effectively doubling the quadrature output.
This means more electronics. The A and B outputs from each side are conditioned by separate decoders (usdigital ls7184) and input to a microcontroller as direction and speed to schedule drive motor commands. Both signals could be sent to a single microprocessor input through high speed diodes, doubling the sample rate to that pin.
This seems like a workable solution to the limitations imposed by printers. And, with more sophisticated equipment, a way of easily doubling resolution.
I stuck a printed optical disk to each side of a CD, shifting the alignment on one side to dissect the pattern on the other.
I'm not necessarily claiming anything new here. The image below conceptualises the four phases as a % of the cycle for each pair of sensors; that is, 0, 50 on one side, intervening, 25, 75 on the other. I would like to say Octal, but in reality, seperate quadrature outputs overlapping by 45 degrees - 8 outputs off one wheel.
No doubt it's been done before...
Last edited by rcheshire; 24-12-2012 at 05:48 AM.
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