
Electrick: Low-Cost Touch Sensing Using Electric Field Tomography - CraneWorm
http://yang-zhang.me/research/Electrick/Electrick.html
======
splatcollision
This is awesome. Does not compare to touchscreens, but wildly useful for
hacking interactive real world objects. Would appreciate a DIY hardware guide
from the creators and open source code for processing the signals. The full
paper does have some detail but not sure if it's enough to run with.

------
anu7df
This is cool. I wonder if in addition to changing the current injection
electrode, dynamically varying the resistance at the electrodes can help
increase the resolution.

Changing the resistance dynamically can change the current distribution on the
surface. This can be used to change the gradient around the touch location to
further refine the position. Edit: clarity and typos

~~~
taknil
Well I guess you have a topic for your next whitepaper. :D

------
joezydeco
I'm really excited to see electric field sensing mature like this, but I sense
a potential problem with RF emissions down the road. Can this stuff get FCC
class-B certification?

~~~
yourapostasy
The paper seems to say they use 200 kHz sinusoidal waves for the field. If
that translates directly into what I see in an FCC table of frequency
allocations, then that is in the AERONAUTICAL RADIONAVIGATION regulated by FCC
Rule Part Aviation (87) [1]. They are driving the signal at 6 Vpp (peak-to-
peak), at most 0.42 mA current with the lowest-resistance spray. I don't know
how to even crudely calculate radio interference from those specs, so would
appreciate someone giving guidance on where to look for a start.

What worries me about this approach is the need for calibration. I don't see
anywhere that indicates they've tested to see the effects of the wearing down
of the topcoat and conductive spray layer upon the accuracy. It would be cool
to be able to simplify a light switch installation to slap(electrodes)-spray-
spray-calibrate, it would suck if I had to re-calibrate once every few years.

Now if we can figure out how to beam low-voltage, low-amperage power over
building distances and through insulation, then we could remove _a lot_ of
copper runs. Beam just enough low power to drive and sense these kinds of
control surfaces, and control relays sitting in front of the actual devices'
electrical connections.

[1]
[https://transition.fcc.gov/oet/spectrum/table/fcctable.pdf](https://transition.fcc.gov/oet/spectrum/table/fcctable.pdf)

~~~
joezydeco
That's great detail, thanks for looking that up. The 200Khz wave may not be a
big deal, but when you start getting strong harmonics then things really go
south in your certification tests.

Once on a capacitive screen controller design I had to stick in some pseudo-
randomization on the electrode PWM to avoid this coupling. It was a pain in
the ass.

------
mrfusion
I think there is a lot of potential for sending with electric fields. A lot of
animals like sharks can basically see using an electric field. It would be
amazing if we could replicate that.

~~~
jschwartzi
I'm imagining a replacement skin that sends touch signals to the brain, so if
you've lost an arm you can feel using your prosthesis. I know it wouldn't work
for non-living objects, but imagine being able to regain the sensation of
human touch.

------
TeMPOraL
Didn't Disney present similar technology a few years ago?

~~~
raphman
"Touché: Enhancing Touch Interaction on Humans, Liquids, and Everyday Objects"
[1] and "Botanicus Interacticus: Interactive Plant Technology" [2] used a
single electrode and machine-learning classification in order to distinguish
between different types of touches and touch locations.

Using multiple measurements (as Electrick does) provides much more robust
tracking than these.

[1]
[http://www.chrisharrison.net/index.php/Research/Touche](http://www.chrisharrison.net/index.php/Research/Touche)

[2] [https://www.disneyresearch.com/project/botanicus-
interacticu...](https://www.disneyresearch.com/project/botanicus-interacticus-
interactive-plant-technology/)

------
Animats
Cute, but very low resolution. The paper describes sensing a 4x4 array. Multi-
touch is possible, but fingers closer than 10cm can't be resolved. The paper
doesn't say anything about ambient humidity. That will affect this approach.
So will skin dryness.

It's nice, but not better than existing touchscreen technologies.

~~~
pharrington
While I agree with you that transparent touch screens are currently
underutilized in the sex industry, this technology will enable things beyond
your wildest dreams.

~~~
_-__---
I'm sorry if I'm missing something, but did you mean to reply to a different
post here? I don't quite see the relevance of what you're saying to anything
that the original post covered.

~~~
pharrington
Yes, OP said nothing about sex work. No, I am replying to the right post.

------
mrfusion
Can anyone eli5 how it works? I couldn't seem to tell.

~~~
tyingq
How about ELI15? Touching a conductive surface reduces voltage in that area.
Place sensors around the perimeter, and rotate the source of voltage to
triangulate the location.

------
JabavuAdams
Would this be useful for robot touch sensors?

