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Optical Mouse Used As Cheap Motion Sensor
drphil writes " Dr. Tuck Wah Ng, a member of the Faculty of Engineering at the National University of Singapore uses an optical mouse as a cheap non-contact motion sensor in his research. If a resolution of a little less than 60 microns is sufficient, you really can't beat the price. Dr. Ng has studied the viscoelastic deformation of plastics using a hacked optical mouse - published in J. Chem. Ed. vol 81, p 1628, 2004. You'd need to be a subscriber of the journal to see anything but the abstract, but any university science/chemistry library would have a copy of this issue of the Journal of Chemical Education. (Viscoelastic deformation, in plain English, is the degree to which a plastic stretches when you pull on it)"
Coralized link here.
That's a nice link there, I'm sure the first 1 or 2 people who saw it may have been interested.
The article clearly says to go to your nearest Chem Dept Library and read the article.. Sheesh.
Not really new-I'm sure many Slashdotters who are IEEE members enjoyed the September 2004 issue of IEEE Computer magazine which covered the theme of biologically inspired robotics. There is a paper in that issue by S. Thakoor et al. which uses an optical mouse chip for terrain feature tracking for a flying aerial robot. You can't read the paper if you don't have IEEE digital library access, but here is the link:
3 8abs.htm
http://csdl.computer.org/comp/mags/co/2004/09/r90
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..who are trying to use this server's enrollment system just right now.
Well, I can't access the page currently but if it is what I think it is this has already been done. A high school student I knew built a optical mouse motion sensor as a project. It tracked the floor, and could be used as a human-interface controller for a robot or as the robot's position tracking mechanism.
He interfaced it to a microcontroller as well, which was the real difficult part. PS2 to a serial port, then the software to interpret it. Unfortunately the thing was handicapped by the 8 bit memory, but it was still pretty darn cool.
This was part of Andrew's Leap, a program sponsored by CMU and taught by professors to a select few high school students. Hopefully what this doctor has done is a bit more complicated.
Researchers looking into the hearing of flies attach the fly to a fixed support above it, and allow it's feet to touch a ping pong ball dotted with sharpie-marker dots. The ball rests on an optical mouse with some foam to hold it in place. By playing sounds from different directions and measuring where the fly moved in reaction they where able to determine how directionally-accurate the hearing of the fly was.
This is all per some TV show, maybe Discovery's This Week
If a resolution of a little less than 60 microns is sufficient, you really can't beat the price
Hmmm. This inspired me to try to see if I could move my optical mouse without moving the cursor. It's possible, but very difficult. It obviously depends on the sensitivity setting.
I'm not surprised that regular or optical mouses are used for something else than moving a cursor on the screen. I had a Path Finder Robot project back in 1998.
It was a very dumb small robot but it had to be able to move forward, backward and rotate, which needed some way to estimate distaances. And the cheapest way of doing it was to put a mouse underneath.
Basicaly a mouse is a tool to measure delta's (differences in distances), the optical ones are doing it very accuratly and without actual contact. That's why it's a good tool in that case.
You used to be able to order optical sensors and other generic components by the box for less than the cost of a mouse.
I haven't checked lately, but why is it cheaper to hack a mouse than build a simple circuit? ...]
[Sound of luser googling
Hmmm, maybe it is cheaper.
I can't find prices at places like http://www.aromat.com/pcsd/product/sens/select_mot ion.html
, so maybe "if you have to ask the price, you can't afford it".
sigs, as if you care.
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"God fights on the side with the best artillery." - Napoleon, Marshal of France - speaking truth to power
but "motion" cannot be described in "microns." I think you mean "cheap displacement sensor".
And viscoelasticity is not necessarily a plastic-related thing. Some metals and composites may strain in a viscoelastic manner. Biological tissue is also generally deemed viscoelastic. Basically, it means: the amount of stress in the material is proportional to the rate at which it is displaced (or strained, in more correct terms).
IWARS.
People, in general, disappoint me. Politicians even more so.
60 microns is too low a resolution for that purpose.
Isn't this what mice do already?
Just another way to restrict the flow of publicly funded research.
Schools get tax dollars, therefore the results of any research should be freely available to the public, unless its some sort of classified governmental stuff...
Restricting knowledge only serves to retard growth, and keep the 'special ones' in power.
---- Booth was a patriot ----
Read about it here. The work was presented at Ubicomp 2004 a couple of months ago.
their webserver has undergone Viscoelastic deformation
any university science/chemistry library would have a copy of this issue of the Journal of Chemical Education
Not Bob Jones university. On the 2,253,532nd day, God created the optical mouse, and thou shalt not play God, except on TV with an (800) number subtitle for donations.
--
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I've seen quite a few papers recently that talk about using multiple cheap (<£30) webcams to do gesture recognition. Ok the images aren't great but the improvements you get from using £1000+ video set-ups with fancy lenses etc aren't that great.
I used to have a better sig but it broke.
It's a pretty common surname used here in Singapore and in its original form it's a word in one of the Chinese dialects. It's actual pronounciation is something like "urn", replacing the 'n' with an 'ng' where the tongue remains stationary instead of moving up to touch the ceiling of your mouth.
Searching Google Scolar for "optical mouse motion sensor Ng" provides some useful information. The PDFs are slashdotted like others have mentioned, but the "View as Html" pages are the google cache. The graphs are worthless, but the text is all there.
This got me thinking... me and my geek engineer brain...
Seems to me by mounting a small mass between springs right above the sensor, you could probably measure acceleration fairly accurately. The spring deflection would be precisely related to the acceleration, the mass, and the spring constant, two of which are known (or can be measured independently) and are fixed values.
F=ma, where force = mass times acceleration
F=kx, where force = spring constant times displacement
so
a = kx/m
(Figuring out the units is left as an exercise for the reader.)
So as the combined mouse/spring/mass assembly was accelerated, the cursor would deflect accordingly. Calibration would be straightforward: since k is fairly linear for most springs (within small ranges), and m is fixed, simply turning the sensor on its side (e.g., subjecting it to exactly 1.0g) gives a very nice data point.
Might be a cheap and fun way to build a sensor, say for measuring cornering force on your car, etc. Also might be a neat high school physics class experiment.
That is, unless Microsoft already patented that use... *grin*
--Brandon / Split Infinity Music
Those new meters would sometimes come with a pulsed digital binary output. You connect that output terminal to a controller/computer and read the pulse. Each pulse is like 1/2 kilowatt hour. You can easily rig something up to read the power consumption.