Sunday, February 14, 2010

Designing the overhead light track for WiiCane

Zach and I are beginning to look at the redesign of the overhead light track for a production version. We plan to use a clear 1" or 3/4" square clear acrylic extrusion . This is a highly transparent material that hopefully will not introduce any optical bending or distortion of the IR light emitters. This material costs about 40 per foot when bought in quantities of 1000 feet. For us to manufacture 50 sets we will need  50 times 32 or 1600 feet. At this quantity, the raw material cost is $12.80 for each WiiCane set.  It comes in 8' lengths, so we will cut these in half; when all of these sticks are bundled up for shipping, the entire package will be only 4' x 3" x 3".  With a four-sided extrusion, we will be sliding the circuit boards in through the ends rather than laying them down as with a three-sided shape. we also need to figure out how to fasten the boards to the interior of the tube from the outside. The inside dimension is either 7/8" or 5/8".  It will have to be possible to ensure that the lights lie flat and evenly spaced within each section. Zach is currently deciding whether the material of the boards will be rigid or flexible; this will impinge on how these sections will join up and how they will be mounted to the ceiling. I want to continue with the assumption that the apparatus can be supported either with ceiling clips or on tension poles. I think some people will not be comfortable shooting nails into their ceiling, and they might prefer the pole set up, which will be priced higher ($1,000 vs. $1,250). We will continue to 3D print the suspension clips for now. We will need 50 times 8, or 400 clips for the first batch. 

We should consider the virtue of making a suspension clip that combines the structural and electrical functions. If the board substrate is like a tape, then I do think we need to add some kind of tounge to add rigidity, and this could also slide into the adjacent section acyrlic section and snap into place, thereby making the connections of the three conductors. I am going to start ordering some sample materials and we can run some tests here in the office. It appears that brightness and equivalent light levels in the 64 IR LED's in the array is going to yield the best performance, and the only way we can be sure that it works is by testing. I reviewed a video from the Overbrook testing and noticed that the good chiming feedback stops near the end of the course, which may be caused by some amount of power drop off along the length of the course.

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