Comments on: Scratch input

By: cassetti

cassetti — Tue, 11 Aug 2009 14:23:16 +0000

Few things, first off every blog repeating this is saying the same thing “High Pass Filter”

You can easily make this yourself. A First order (6dB per Octave) High Pass filter is simply a Capacitor! Look online to determine how many farads to get the desired filter you wish.

I will be installing one as soon as i can find some sort of software for linux (ubuntu)

I have a complete home audio system connected to one computer running Linux. It would be WONDERFUL to have sound control when we can’t find the Logitech Harmony or the RF keyboard/mouse combo.

Any links to any sort of software?

By: Ben

Ben — Tue, 18 Nov 2008 16:39:54 +0000

Fantastic video and project. Well done to all those involved.

Would love to try this out myself. Any idea if the software is available to try?

Thanks to Johnny Lee and his web-site for pointing me in the direction of this project.

Anyone with any details about where to find resources/software for this please post them.

Thanks!

By: srilyk

srilyk — Mon, 17 Nov 2008 18:52:17 +0000

@mike – you only need a “hotkey”, i.e. two short taps, followed by your command.

@ellisgl – volume may not be the same, but the sound should always have a relative speed difference among the 4 inputs. Volume “don’t enter into it”, the same thing is in this case – it’s not the volume but the waveform that’s measured/analyzed.

This is a really cool idea… although I must confess I’m thinking along the lines of a security device – could you imagine miking floors, in combination with camera/thermal/etc? You could probably fairly “easily” get the exact location of a person… combine that with a fast turret/airsoft gun combination… w00t! (or real gun, if that happened to be your thing.)

By: Mike

Mike — Sun, 16 Nov 2008 21:30:52 +0000

I agree. I think for quality of sample and accuracy 4 sensors could be placed on the 4 corners of the surface you are using. I think that as few as 3 could be successfully used, but for a technology like that to be implemented successfully you would need to have >99.999% recognition, or higher. Even 1 false input in 10,000 would cause problems.

That movie in French was good, but I think that you can see there are inherent problems with such things as on surface keyboards, because it would be nearly impossible for the technology to recognize when a button is held, making many hot keys and short cuts unusable.

By: EllisGL

EllisGL — Sun, 16 Nov 2008 06:19:54 +0000

4 sensors would be needed to figure out position. Also a calibration would have to be needed, because each time you do something, even if you tapped the same place, the volume isn’t going to be the same. Maybe tap each corner 3 times. Light, medium and hard.. Just an idea..

By: bountyx

bountyx — Sun, 16 Nov 2008 05:03:11 +0000

very innovative, i can think of a million different uses for this. How about using a unique gesture to on your car window to open the door?

By: Adam Ziegler

Adam Ziegler — Sat, 15 Nov 2008 15:53:46 +0000

piezo

By: speps

speps — Sat, 15 Nov 2008 11:46:09 +0000

I already saw that applied here :
http://www.journaldunet.com/solutions/systemes-reseaux/reportage/08/0208-surfaces-intelligentes-reversys.shtml

It’s in French sorry but the video should be enough.

By: polymath

polymath — Sat, 15 Nov 2008 10:15:22 +0000

if they get this to work in clothing I’ll really be impressed. if nothing else it will give men the world over an excuse to scratch themselves in public.

By: john

john — Sat, 15 Nov 2008 03:18:56 +0000

yay im putting microphones in every wall

By: morden

morden — Sat, 15 Nov 2008 00:53:07 +0000

Look back at the recent post regarding the capacitive resistance touchpad using the metallic cloth and 4 points of contact. You could set up 4 scratch sensors and determine x/y location simply by assuming a matrix size they represent and using the strength of the scratch to determine to which side they are closest too.

70% right 30% left = x+20 on a 100/100 grid.

By: Taylor Alexander

Taylor Alexander — Sat, 15 Nov 2008 00:19:25 +0000

I feel like you could make a surface that had micromachined groove patterns that were different from different directions, so that each direction (up, down, left, right) produced a unique sound when something scraped across it. Then you could use dead reconing to get an approximate shape of each individual movement, which would make gesture recognition better I wonder if a fresnel lens would be a good place to start? They already have directional grooves in them.
-Taylor

By: Satiagraha

Satiagraha — Fri, 14 Nov 2008 23:38:31 +0000

I have to admit, this is a fantastically detailed report for what seems like a weekend experiment. Kudos to the authors, procrastineering, for an innovative little project.

By: macegr

macegr — Fri, 14 Nov 2008 23:36:36 +0000

It looks like my earlier comment isn’t going to come back. Anyway, I was pointing out this technology is used in Elo Touch’s acoustic pulse recognition touch panels. I worked with them at elo for a small contract job once.

Basically it’s just two microphones on a sheet of glass. A machine taps the glass in a matrix and the stereo sound profile is recorded, maybe classified into an FFT fingerprint. Then the incoming audio is compared against a database of stored profiles. A normal sound card is enough to get good resolution, though of course Elo’s hardware is optimizing the signal and ADC so you don’t actually have to plug a line in to your computer. All the real work is in the software driver; optimizing the search for known patterns, rejecting noise, making it all fast enough for instant touch response.

You can download whitepapers with more in-depth discussion of the technology on Elo’s website.

By: icefox

icefox — Fri, 14 Nov 2008 23:07:05 +0000

Since most of you seem to be debating my comment about triangulation, let me just throw what I was thinking about when I was thinking of. I do actually agree that 3 may work somewhat better.

Do you know how the police (and other companies) can track cell phone locations? A call tower, or antennae, can determine the range from itself to a point, the phone. This forms a circle of where it could possibly be. A second antennae can form another “range circle” and narrow it down to 2 points in space. A third can be used to determine the exact point the cell phone, rather than 2 possible ones. My old math teacher actually was in the FBI.

Now apply that logic to scratch input, but with much shorter ranges. It could be done with 2, but 3 would be more accurate. 1 however, just seems overcomplicated to me.