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Measuring cable length using optical encoder — Parallax Forums

Measuring cable length using optical encoder

EoghanEoghan Posts: 4
in BASIC Stamp
Hi,

I am building a cable robot and want to integrate a closed loop system. I wish to measure the change in thin cable lengths at certain point but I can not find anything suitable to do this. I basically want a linear encoder to measure the distance that the cable moves, but every encoder that I have found only works with codestrips.

Any help would be appreciated,
Thanks

Comments

  • PublisonPublison Posts: 12,366
    Welcome to the forums. Your other two posts have been deleted, as they where duplicate and in the incorrect category.
    Please read the Forum Rules here:

    http://forums.parallax.com/discussion/134682/forum-rules-and-guidelines#latest
  • DigitalBobDigitalBob Posts: 1,513
    What about a linear string potentiometer.
  • EoghanEoghan Posts: 4
    edited 2019-02-01 17:00
    Wont work unfortunately, the device I need cant interact physically with the my cable.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2019-02-01 18:27
    If the surface of the cable is variegated or textured, you might consider an optical mouse sensor.

    BTW, I'm puzzled that the device can't interact physically with the cable. What would be wrong with adding encoders to the winches that control the cable or to the pulleys the cables ride over?

    -Phil
  • EoghanEoghan Posts: 4
    Phil Pilgrim (PhiPi) wrote: »
    If the surface of the cable is variegated or textured, you might consider an optical mouse sensor.

    BTW, I'm puzzled that the device can't interact physically with the cable. What would be wrong with adding encoders to the winches that control the cable or to the pulleys the cables ride over?

    -Phil

    A optical mouse sensor would be perfect for the job, however the only information that that I can find online, is too tear apart an old PS/2 mouse and use its parts, do you know of any other way this can be done?

    -Eoghan
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    You can get optical mouse sensors from eBay, but building a usable device with one could be a challenge. Parallax once sold an optical mouse sensor kit. Here's a link to the manual, which includes a schematic:

    https://www.parallax.com/sites/default/files/downloads/28560-Mouse-Sensor-Kit-Product-Documentation.pdf

    Your best bet is probably to repurpose either an optical (serial or PS2) mouse.

    -Phil
  • EoghanEoghan Posts: 4
    Phil Pilgrim (PhiPi) wrote: »
    You can get optical mouse sensors from eBay, but building a usable device with one could be a challenge. Parallax once sold an optical mouse sensor kit. Here's a link to the manual, which includes a schematic:

    https://www.parallax.com/sites/default/files/downloads/28560-Mouse-Sensor-Kit-Product-Documentation.pdf

    Your best bet is probably to repurpose either an optical (serial or PS2) mouse.

    -Phil

    Thanks very much for your help Phil, Repurposing a PS2 mouse seems to be the way to go.

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    I'm still perplexed that a rotary encoder can't be employed on the winch or pulleys. Care to elaborate?

    -Phil
  • kwinnkwinn Posts: 8,697
    Phil Pilgrim (PhiPi) wrote: »
    I'm still perplexed that a rotary encoder can't be employed on the winch or pulleys. Care to elaborate?

    -Phil

    Also perplexed, please do elaborate. More info might result in a better suggestion.

    I am not sure the mouse idea would be very accurate. The image is going to have randomly placed patterns and areas that may be smooth enough that no movement can be detected. Think of what happens when you place the mouse on a smooth single colored surface.
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