OptiStructures

Abstract

A recent topic of considerable interest in the "smart building" community involves building interactive devices using sensors, and rapidly creating these objects using new fabrication methods. However, much of this work has been done at what might be called hand scale, with less attention paid to larger objects and structures (at furniture or room scales) despite the fact that we are very often literally surrounded by such objects. In this work, we present a new set of techniques for creating interactive objects at these scales. We demonstrate fabrication of both input sensors and displays directly into cast materials -those formed from a liquid or paste which solidifies in a mold; including, for example: concrete, plaster, polymer resins, and composites. Through our novel set of sensing and fabrication techniques, we enable human activity recognition at room scale and across a variety of materials. Our techniques create objects that appear the same as typical passive objects, but contain internal fiber optics for both input sensing and simple displays. We use a new fabrication device to inject optical fibers into CNC milled molds. Fiber Bragg Grating optical sensors configured as very sensitive vibration sensors are embedded in these objects. These require no internal power, can be placed at multiple locations along a single fiber, and can be interrogated from the end of the fiber. We evaluate the performance of our system by creating two full-scale application prototypes: an interactive wall, and an interactive table. With these prototypes, we demonstrate the ability of our system to sense a variety of human activities across eight different users. Our tests show that with suitable materials these sensors can detect and classify both direct interactions (such as tapping) and more subtle vibrations caused by activities such as walking across the floor nearby.