learning the ropes

I want to be able to work with two pulleys simultaneously, so I’m adding the rotary encoder to wooden pulley I started building last week. The PS/2 mice have turned out to be quite a clever hack because each one gives me two rotary encoders and three switch inputs in exchange to two pins on the Arduino. I’ve started thinking a bit more about multiples — and while this may be a little premature, I want to work out a bit of the technical end of this before getting too heavily into final fabrication.

I’ve invested rather heavily in this for the past two days. Perhaps because this is more comfortable for me than other things that need to get done now — like preparing for the mid-term presentation.

What this does mean, however, is that I have the pieces for a much more modular system. I’m envisioning a hub that I can plug each pulley into using a single CAT-5 cable. This makes the performance setup clean — and won’t require any soldering.

Today I worked on fabricating another two pulleys out of wood. I finished drilling well-aligned shaft holes in the side pieces and made new pulleys out of particleboard and plywood. The most time-consuming part of this process was cutting the circles out of with the bandsaw. I remembered that there is a jig for cutting circles, but didn’t want to spend time figuring out how to construct it in order to cut six circles. I first started by cutting around the contour of the circle, but ended up just making tangent cuts and then sanding away the excess. I was really trying to have another pulley finished by Saturday so I could test two of them with Wendy and Martha, but that doesn’t seem to be realistic at this point. I still have to make the encoder structure.

The completed wooden pulleys:

I constructed another P2/2 Connector Breakout Board so I can attach another pulley to my performance system. This time, I’ve annotated the photos in Flickr so the next time I construct one of these I don’t have to think how to build it again.

It felt very good to spend much of the day in the shop working with my hands. Much of the week, however, was spent struggling with how to make progress on the materials/form of the rope&pulley and also struggling with what I am producing.

Earlier in the week, I was researching materials. There are two directions I am considering: natural wood (mahogany, maple, walnut, cherry, etc) or recycled parts. The natural wood direction comes from my appreciation for naturally finished wooden instruments: electric and acoustic guitars, pianos, etc. The recycled direction relates more closely with one of the themes of the project which is, in a way, the recycling of musical content and the loop-based music metaphor.

When I got stuck researching, I tried to work a bit with the form. I started with raw sketches and then tried to work material in Google Sketchup.

I spent too much time trying to manipulate the materials in Sketchup, though, and became frustrated. A breakthrough occurred when I realized that I could use foam to quickly work through ideas. My previous prototype was cardboard, which is durable, but not easy to work with quickly.

Pretty in Pink: A photo essay about my process today. Click on the individual pictures for notes.

I made three new prototype shapes today and I’m looking for feedback on them.

I’m crafting another rope&pulley system — this time out of wood to address some of the problems I’ve observed with the cardboard prototype — and also to explore materials.

1-inch x 3-inch pine stock cut into rough forms to make a new set of pulley supports. I’m going to resize the paper templates I used when I created the cardboard prototype so I can accurately drill and shape these pieces.

Today I made some revisions to the Max/MSP patches that interface the rope&pulley to the computer. In preparation for the videotaping session I’m doing with Wendy tomorrow, I wanted to make sure that it was easy to switch back and forth between the different patches. When I’ve done that in the past, I’ve always run into trouble — I invariably forget to configure some part of the patch. While cleaning up the patches I found that I could structure things in a way that may make it easier to combine them should the need arise.

I have three different versions of the patch now:
Audio

- rope&pulley controls playback direction (and optionally speed) of user-selectable .wav audio samples.

MIDI

- rope&pulley plays notes on a MIDI synthesizer and can adjust two user-configurable MIDI realtime controller values.

Movie

- rope&pulley scrubs a looped QuickTime movieplays. Scrubbing rate is mapped to the pulley’s rotation speed and the scaling of this value can be adjusted from the patch.

I built a rough foot pedal assembly for the rope & pulley system. I’m not quite sure what to make of it just yet, but it didn’t feel right. Previously, pulling the rope towards my body would trigger a note on the synthesizer. As I pulled with increasing speed, the pulley system would increase the volume of the note along with a sound modulating parameter. As I pulled with decreasing speed, the system would decrease the volume and modulation parameter. Once the pulley stopped rotating, the system would turn off the note on the synthesizer. Today, I changed my code so that the rope only controls volume and modulation. I used the two foot switches I built to trigger two different notes on the synthesizer. It felt a bit more like playing a piano with my feet. I felt like I couldn’t move as freely because my feet needed to be on the switches for the notes to stay on.

Ideas:
- Maybe there is an “initial state” of the instrument — akin to an open string on a guitar or violin. (This can be tuned to the user’s preference). This way, stepping off the footswitches still allows sound to occur when the rope is pulled.
- Does it make sense to allow more than one switch to be pressed at a time? I like the idea of being able to play intervals or simple chords with the system, but it doesn’t make sense with the string metaphor.
- This is the synthesizer setup — what about the sample playback setup? What experiments can I do there to push forward a bit?
- How do I capture a “gesture” with the rope like a rapid direction change?

Excerpt from a short videorecording I made to see what I looked like performing the Rope & Pulley. I’ve been working on the Christmas Carol all week and am not sure what I’m going to be able to present in class tomorrow night. This is a return to the original thinking behind the project, but at least I will be able to present something if it is entertaining.

In the video, the system is controlling the volume of audio playback. If I were to stop pulling the rope through my hands, the track would stop playing and the volume would decrease.

Today I converted my pulleys to work with the new detection strategy. Instead of using the outer rim of the pulley to rotate the mouse ball, I’m going to attach the optical encoder wheel to the end of the pulley’s shaft. To avoid building the pulleys again, I’ve decided to patch up the hole where the bearings were seated.