Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Distance Measurement Sensor

Distance Measurement Sensor

Distance Measurement Sensor

Hello All. I am trying to make make a digital measurement tape (Round type which retracts back once pulled out and let go). So, as the tape or thread is pulled out, the distance sensor should be able to detect how much length has been pulled out. I had a hall sensor and a few magnets in mind. But with this I believe I cannot achieve the kind of accuracy that I'm looking for. I am looking for an accuracy of 1 mm and be able to measure from 0.1 cm (or at-least 1 cm)to 3 meters. Can anyone please suggest any sensor ? What type of sensor would be suitable for this kind of application and accuracy ?

RE: Distance Measurement Sensor

Get a shaft encoder like the type used on the back of motors. They're called "incremental encoders".

Here's examples. Encoder Examples

There are a bunch of types for a bunch of applications. You have to figure out what resolution you need. They can run the spectrum on cost from a few dollars to thousands of dollars depending on many variables.

You can likely find some inexpensive ones on ebay as a lot of little bitty 'toy' motors have them.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Distance Measurement Sensor

I would suggest a linear optical encoder. In fact, such a product already exists, although I suspect the price point is way beyond what the OP thinks the cost is going to be. Nevertheless, the link below shows performance up to 200x better than the OPs requirement


In fact, Renishaw quotes resolutions down to 2.5 nm for some of their other products:

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close