Future visual microsensors for mini/micro-UAV applications

New classes of small and micro-sized UAVs, with wingspans on the order of meters and tens of centimeters, respectively, present interesting challenges to the field of autonomous flight enabling sensing and control technologies. There is currently a desire to develop a sensor/control suite that will allow such UAVs to fly through complex environments, such as in an "urban canyon" or underneath a forest canopy, at altitudes of just meters above the ground. The development of such capabilities requires new approaches for perceiving the environment. There is an increasing interest in borrowing ideas from flying animals such as insects, which are able to fly through such environments with high reliability. This has led to the development of optical flow sensing techniques that currently are able to provide such capabilities as altitude control and terrain following. However, more difficult tasks such as flying in the urban canyon or in a forest require advances in image processing that allow obstacles to be reliably detected by a machine vision package weighing tens of grams, including all optics, hardware, and software. A blueprint for such a visual sensor is proposed that makes use of anticipated developments in microelectronic technology. With disciplined "best engineering practices", cellular nonlinear network techniques can make significant contributions to the development of such sensors.