Touch sensitive controller

#1

Hi, i was thinking about building some kind of touch sensitive controller, where you can use your hands to control certain parameters as well as a percussive device.

Now i found this project: https://www.expressivee.com which is even going further than i expected.
sample video: https://www.youtube.com/watch?v=wgvDo-oDGF8

it seems quite advanced and with 400 € reaching quite deep into your pockets.
I don´t want to recreate the same instrument, but a diy solution.

Could you share your thoughts, what could be used do measure pressure and movement, like in a X,Y, and Z axis, mixing them together to control certain parameters?

any input is welcome.
thank you

#2

pressure = force sensitive resistor
xy axis = joystick...

so a piece of wood glued to a joystick and an fsr on top should get you there :slight_smile:

#3

Have you thought about Capacitive sensors.
They seem rather simple.
Check this out..

#4

Thank you for your advice.

I thought about a joystick, but i´m not sure, if it offers enough sensitivity, but they are cheap, so i´ll try it out. :slight_smile:

i´ll definitely look into force sensitive resistors and Capacitive sensors!

#5

capacitive sensors will not give you pressure, just contact as far as i know. so it is an on/off switch basically.

#6

I built one of these:
http://www.coagula.org/content/pages/coagula-midi-ribbon-controller-20-1

#7

The Expressivee Touché seems to be described in this patent: EPA link, english translation

#8

Thank you for all your inputs, very helpful.
yes, i would have to combine a capacitive sensor 8or an alternative) with a pressure sensitive one, i guess.

i´ve been looking into the Coagula MIDI Ribbon Controller, but consider it as an extra project, which maybe can later be combined.

Also thanks for the patent link, it´s quite advanced as it seems, but great to get some info on the original functionality.

this can get me started, thnx!

#9

I have one of these leftover from an old project that never was I am thinking of using with my Axo -- seems like it could work perfectly!

#10

Actually you can 'sort of' get some expression from them as the returned value is based on proximity, or in this case amount of contact... (tip of finger = small signal, entire finger = large signal)... I've recently done this on my ribbon controller where 4 cap sensors send note on/off with velocity based on amount of contact, and aftertouch if the same note is still playing. It isn't perfect, but 'kind of' works :slight_smile:

#11

interesting, how much resolution do you get? how many different values can you distinguish?

#12

@lokki I'm still playing around with the code and working on shielding the circuit for more control but currently I can get velocity CC values typically 40 to nearly 100+. You set a lower threshold that must be broken before you arrive at a CC value, and this I typically add a buffer to since it floats a little pad to pad.

(edit) I should mention that I am using the internal hardware cap touch function of the Teensy LC which is apparently much more powerful than some of the simpler systems/circuits.