Hello all,
I am looking for a linear sensor for my project (through arduino or pi) that would measure the position of a 3mm rod (end position) that moves fore and aft pretty fast (max range of 30mm, typical range of 10mm and frequency of 10Hz).
Idea is to measure the position, use it to move a servo to move another rod.
Where should I start? rotary or sliding? anything better? (newbie here).
Thanks,
Nr
Measurement accuracy? Budget?
measurement accuracy around 0.5mm.
I expect quite a few cycles (10Hz for 2hrs would be a typical ‘run’), so I am a bit concerned with the life cycle of mechanical sensors.
IR are interesting but I don’t have much space; I can’t afford to fit the end of the rod with a large target (more than 1x1cm).
Budget is limited; say around $30.
Thanks,
Nr
nr765:
measurement accuracy around 0.5mm.I expect quite a few cycles (10Hz for 2hrs would be a typical ‘run’), so I am a bit concerned with the life cycle of mechanical sensors.
IR are interesting but I don’t have much space; I can’t afford to fit the end of the rod with a large target (more than 1x1cm).
Budget is limited; say around $30.
Thanks,
Nr
Good luck finding anything off the shelf at that price. After a few $k of engineering time, you could probably do it with one of these: http://ams.com/eng/Products/Position-Se … ors/AS5304
What’s my toughest requirement; the frequency needed?
What about something like this: http://www.vishay.com/docs/57115/20lhe.pdf ? Above budget a slightly limited range but could work.
Would converting linear position to angular position makes things easier? there seem to be loads of cheap sensors to measure angular position.
What about it? You found it, read the specs to see if it does what you need.
[sigh]
Look, you’re changing your requirements. You said you wanted something for under $30 then ask about a $100+ sensor. There’s a reason I asked what your budget is: you can find sensors that meet your needs, but you’ll need to spend more than $30. If you said you could spend $1,000 I could probably have found you a sensor literally in less than a minute.
You don’t want mechanical sensors, so that gets rid of all the inexpensive linear potentiometers as possible solutions.
The best advice I can offer at this point is to step back and make sure you really know what you’re asking for, what the accuracy & precision is, and how much you can afford and how much time you have to spend integrating this.
Sorry mate. Was just trying to get a bit of advice. As you’ve probably seen from my posts, I am newbie here.
I don’t think my requirements have changed much; I did try to give as many relevant details as I could in my first post; you asked for details of budget and accuracy, I gave them. Has my budget changed? Since we’re talking of a price range between $1 and $1000; I think I was fine mentioning a $100 sensor when my initial guess was “around $30” (never said below).
I never said I didn’t want mechanical sensors; I was just sharing some of my findings (i.e. that their life cycle seems short for my use); my hope was to get some feedback on this (I am right?).
Then the Vishay sensor you posted will be fine. 10Hz for 2 hours is well within its lifetime and the accuracy is within your spec.
Vishay sensor: You may have to reconsider. Max speed of the piston is 60 mm/sec. That does not match with the 10 Hz requirement against the full 30 mm range, or even typical motion range of 10 mm.
Yes, you’re right. That’ll be an issue.
I havent found anything else yet in that price range.
Maybe a stupid idea, but what about using a softpot with a wiper? Seems accurate, cheap and a good lifetime or am I wrong?