meant to get back to you about the Theramin idea I had for a chording glove...sorry, life got busy.
Anyway, you know how one works (http://en.wikipedia.org/wiki/Theramin) right?
So, it occured to me that if you had a loop antenna on the back of your hand, and used flexible wiring down the length of the fingers as the dipole antenna, with different harmonic frequencies for each finger, then as you curled your fingers to 'type' the EM field as measured by the pick up would change depending one which finger curled by how much...
Granted, the back-end circuit would be more complicated, as a 5 channel A-D converter would be needed to process the signal before it reached the control board...but you'd not only get information about which finger was pressed, but by how much [ie, how far it moved] and speed of movement over time data too. which wouldn't be important for typing, but would be very useful for context sensitive applications like painting, control applications, or providing the sensor half of a force-feedback loop.
Add in a 3-axis accelerometer and you've got a full-on position sensing VR interface.
Hrrrrrrm. I know there are Freescale 8-bit uCs that have multiple ADCs on them -- the one that was used on the Defcon badge in 2007 had several ADC lines, enochsmiles and our team and I only had to use one of them for our badge-hacking project. I'd probably want to do that surface-mount and actually fab a board for it, though.
I will for sure look into this further. I've built more wire dipoles than I care to think about, and 30ga wire could be threaded through the stitches of a glove, at least in an early version. I might be a little worried about wire fatigue, though kynar insulation seems to do a halfway decent job of strain relief.
The SpiffChorder code base is open-source, so I could build on that ... this is a pretty fabulous idea, I need to read that page about theremins. (I actually don't know how they work, I look forward to reading the link.)
Thanks, this is a really fabulous idea!
Are you planning on going to HAR (www.har2009.org) by any chance?
Hm. The optical theremin makes me think of another approach: using IR LEDs of different frequencies (assuming I can get those...) and appropriate IR receivers mounted along the palm, and using proxmity to the IR receiver (ie, intensity of light received) to determine position of the fingertip switches. Or maybe some kind of gesture-based thing. For the thumb switches I could use something similar to the reset circuit in Mitch Altman's Trippy RGB Waves (http://www.tvbgone.com/cfe_trippyRGB_instructions.php) kit -- cover up the LEDs to interrupt the light, since those switches are meant to be binary. Though if I can get enough positions out of the fingers, I might not actually need the switches. My hands aren't super-flexible, though -- curling one finger enough tends to make all the other ones curl too -- so the design considerations are going to be interesting.
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Anyway, you know how one works (http://en.wikipedia.org/wiki/Theramin) right?
So, it occured to me that if you had a loop antenna on the back of your hand, and used flexible wiring down the length of the fingers as the dipole antenna, with different harmonic frequencies for each finger, then as you curled your fingers to 'type' the EM field as measured by the pick up would change depending one which finger curled by how much...
Granted, the back-end circuit would be more complicated, as a 5 channel A-D converter would be needed to process the signal before it reached the control board...but you'd not only get information about which finger was pressed, but by how much [ie, how far it moved] and speed of movement over time data too. which wouldn't be important for typing, but would be very useful for context sensitive applications like painting, control applications, or providing the sensor half of a force-feedback loop.
Add in a 3-axis accelerometer and you've got a full-on position sensing VR interface.
no subject
I will for sure look into this further. I've built more wire dipoles than I care to think about, and 30ga wire could be threaded through the stitches of a glove, at least in an early version. I might be a little worried about wire fatigue, though kynar insulation seems to do a halfway decent job of strain relief.
The SpiffChorder code base is open-source, so I could build on that ... this is a pretty fabulous idea, I need to read that page about theremins. (I actually don't know how they work, I look forward to reading the link.)
Thanks, this is a really fabulous idea!
Are you planning on going to HAR (www.har2009.org) by any chance?
no subject
Oh, and found this link for some circuit diagrams (http://www.discovercircuits.com/T/theremin.htm).
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I do hope you can make it to HAR!