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Topic: Measuring Vertical Linear Movement (Read 1 time) previous topic - next topic

Blue_Boy

May 11, 2011, 05:31 pm Last Edit: May 11, 2011, 06:23 pm by Blue_Boy Reason: 1
Hey,
Here's the riddle that needs to be solved: how to measure vertical linear movement?

Four sensors with a travel range of 10cm are needed.
Two sensors with a range double of this, so around 20cm.

Right now I'm using a combination of four bend sensors
http://www.sparkfun.com/products/8606
-> They have the "feel" that we need - constant, small weight.
-> They are not very stable, robust or precise.

And one of these - a drawstring linear displacement sensor
http://www.pennyandgiles.com/Draw-Wire-Linear-Sensors-pd-61,3,,.php
-> Very stable and precise, long range.
-> The "feel" is not quite right. Because of the spring in this sensor, it feels "heavy" when pulled.

So, my idea was "super smooth linear faders" with weights,
but these turn out very hard to find especially in lengths > 10cm.

Do any of you guys have any ideas for other sensors or setups to reach this goal?

So far.
All suggestions very much appreciated,
Jim

liudr

Can you share your setup picture with us? No idea what to recommend. Maybe IR sensors or sonic ranger.

CrossRoads

How about attaching a paper tab with horizontal strips that goes up & down with whatever you have, then a sensor at the base that senses the stripes going past and reports that a count or something similar?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

biocow

I was thinking liner encoder using IR as well.
10 PRINT CHR$(7)
20 GOTO 10

Blue_Boy

Here's a picture of the current setup.
I would prefer absolute readings over encoder systems.

http://www.jimboproductions.be/server/mda/gamehub/PuppetMaster_Photo/DSC_4262.jpg


CrossRoads

Got a picture of it when it has moved some?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Blue_Boy

Nope, sorry.
In fact, in this picture, one out of five sensors has moved already.
The drawstring out of the drawstring sensor has already been extended.
If the "playing cross" is moved higher, the ends of the flex sensors will be pulled upwards,
and bend as a result.

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