Keyer evaluation, Friday, 2006 January 20th, 3pm to 6pm, EA302
Eleven keyers shown together with a "bluebox" wearable computer system;
keyers by (left-to-right) Jorge, Sami, Siraj, Fabian, Bjorn, Fabian, Xiaoxuan,
Ryan, Adrian, Valeri, Mann
In this lab, students were asked to make a high-bandwidth human-computer
interface for being used while walking around, etc.. The reference design
by the course instructor, shown rightmost in the above picture, was
shown, along with other similar reference designs.
Below is a critique of the various designs. It is hoped that the students
will learn from this critique, by learning, not only from their own design
efforts, but also from the design efforts of their peers in the class:
Valeri's keyer was carved (by dremil) from wood, and features two flat
white phone/ethernet style cables, both nicely strain-reliefed, by way
of a metal bar screwed onto the wood.
It has three thumb switches.
Siraj molded a keyer out of plaster, along with a tilt sensor built into it.
The keyer works good. Suggestions: make the wires longer, for connection
to the bluebox. Bundle the wires nicely, or use a multi-conductor cable.
Sami's keyer flips open to give access to the 12 keys in the palm of the hand.
It is worn like a wristwatch (and could also have a wristwatch built into it).
Suggestions: bring the wires out the back of the circuit board, and
have the keys perpendicular to the fingertips (90 deg. rotation from
present angling); this could possibly be achieved by having the
keys slide rather than rotate into position.
Sami came with some plastic safetyglasses and has been looking at Spatial
Soon come the eyeglasses...
Xiaoxuan's keyer is built into hollow cardboard tubing.
This provides a prototype of how the keyer might work inside other
tubular materials such as PVC pipe, etc., as shown in some of the reference
designs previously presented to students.
Stiff wire was used in the rapid-prototyping in order to make solderless
(wirewrap) connections to the switches.
Suggestions: Some form of strain relief is needed for the wires that come
out of the tubing. This could be achieved, for example, by "stitching"
each wire through the tubing a couple of times.
A more flexible wire could also be joined to the stiff wire,
using solderless twist-on connectors. The combination of strain relief,
along with flexible wire, would mitigate the possibility of loose connections.
Bjorn's keyer uses a hollow hand grip, made for a four-C-cell battery holder,
covered in green tape. This makes it possible+practical to build the
bluebox wearable computer right inside the keyer. The three modifier
keys are on top, for thumb actuation. A flexible multiconductor cable
is used to make connection to the wearcomp.
Suggestions: improve the hand-strap so that it spreads out more of the load,
as well as provides better force to perpendicularize the position of the keyer.
Adrian's keyer is made of Femo Polymer Clay (similar to the Sculpey material
that was used to make some of the reference designs).
This keyer also includes a 2 tilt sensors installed at right angles to each
other (tested on the bluebox, it works great!).
There was a short in some of the wiring, which Adrian was able to
fix while the other keyers were being evaluated.
Adrian also began collecting information on making a bluebox.
Jorge's keyer is made from a tree branch (just completed in lab).
Favorite chord progression: Am, G, F, E, and sometimes Dm.
Suggestions: re-work the top portion of the keyer to improve the thumb
ergonomics. The straps (presently rope) could be imroved for ease of getting
it on and off quickly, as well as better comfort, etc..
Ryan's keyer uses a Centronics 36-conductor cable, allowing plenty of
extra conductors for future expansion.
Suggestions: symmetrize the design to alow it to be used ambidexterously;
hand-strap ergonomics could also be improved.
Fabian made two keyers: a standard dodecaambic keyer, along with
a quartambic keyer that has a built-in bluebox interface.
Suggestions: be sure to use the analog input capability of the Atmega48,
to get full benefit from good quality (i.e. continuous change) switches,
Left-to-right: Ryan, Adrian, Sami, Valeri, Fabian, Xiaoxuan, Bjorn, Siraj, Jorge
Fabian with the split-key keyer that many of us have been working on
(accompanied by Valeri on guitar, and Xiaoxuan on piano).