Using infrared sensors and the Phong illumination model to measure distances

Currently, the viability of infrared (IR) as an accurate means of measuring distance depends on extensive prior knowledge of the surface. More specifically, the manner in which a surface scatters, reflects, and absorbs infrared energy is needed to interpret the sensor output as a distance measure. In order to use IR in an unknown environment, one must determine the surface properties during robot operation. The paper details a method of determining the properties of a surface, vis-a-vis infrared reflectance, and subsequently calculating the distance to the surface and the relative orientation of the surface using previously acquired sensory data. We present examples of IR distance measures for various surfaces using known environments as well as examples where the prior knowledge edge has been acquired using sonar sensing. Our results demonstrate that infrared sensors can provide accurate range measurements when used in conjunction with other sensing modalities to fit model parameters during robot operation (i.e. in real-time).