Asynchronous demodulation technique for use in vision sensor image classification and segmentation

This paper presents a novel technique for classification and segmentation of a multiple-object image scene. Each object in the scene is tagged by a flashing LED operating at a specific frequency. The vision sensor, based on this technique, demodulates the captured light signal, omits the background illumination, and performs classification by assigning a unique ID-tag to each region based on its flashing light frequency. The process is performed in-pixel by an asynchronous demodulation and frequency identification circuit, which is designed in a standard 0.6 mu m CMOS technology. Simulation results confirm the validity of the proposed structure. At a frame rate of 250 fps the power consumption is 2.6 mu W/pixel, which is relatively low compared with those of sensors with similar functionality. The structure is intended for use as a low power, inexpensive solution in robot visual position feedback and localization. Copyright (C) 2009 John Wiley & Sons, Ltd.