Beat Blocks - A Tangible Human User Interface for Live Performance and Composition
=BEAT BLOCKS= Created by Steinunn Arnardottir, Nick Bryan, and Hayden Bursk
IDEA/CONCEPT
Beat Blocks tries to break out of the mold of the standard 2-dimensional step-sequencer paradigm. Normally, a step sequncer works as a flat grid of two axes. The x-axis, broken up into columns, works with time stepping through discrete note values, usually 8th or 16th notes. The y-axis, broken up into rows, functions as either multiple voices, one per row, or as pitch increasing with height.
Utilizing the metaphor of playing with blocks, Beat Blocks combines all these possible functions into a single step sequencer by adding a third dimension - stacking blocks. The user still has the standard step sequencer grid to work with. However now, stacking blocks and adding height brings a new way of interacting. The x-axis functions as time. The y-axis functions as individual monophonic voices. The z-axis functions as pitch, amplitude, or as multiple sample selection.
By stacking clear blocks, light can be shined through the blocks from below creating a very nice display of the step sequence.
DESIGN
To design a sensing scheme that could quickly and accurately measure the stacking of clear plastic blocks proved to be somewhat difficult. 1" plastic acrylic cubes while priced fairly cost effectively for size at $1 per cube did not carry much weight. Increasing the size of the cube would increase the weight which would be easier to measure, but it would also quickly increase the cost. Force sensitive resistors were quite inaccurate with a variation of up to %25 for a repeated force.
After much deliberation, we finally settled on using levitating magnets that would act as a platform for the blocks. A hall effect sensor was placed in between the magnets so that when a block was placed on the floating magnet, the magnet would lower until it reached a new equilibrium. This would in turn cause the hall effect sensor increase its voltage output. An increase in voltage could be measure by our microcontroller's A/D converters. By carefully calculating the various changes that this mechanical system could under go, we were able to set threshold values that would indicate whether no blocks, one block, two blocks, or three blocks were being used.
