Gradient driven self-organizing systems

The aim of this paper is to discuss and present some experimental data on the use of optical, chemical and ultrasound sensors to control the motion of single and cooperating robots. The distinctive feature is that in both cases the motion of the robots is not driven by a localized target (e.g. a light, or a sound) but by a concentration gradient such as the one generated by a gas leak. Experiments using a simple optical sensor reading a variable density pattern of dark spots painted on the ground plane, are presented along with experiments performed using simple chemical sensors measuring the local gradient of a substance. Different strategies are discussed based on different configurations of the sensing devices and reflexive motor controls. The goal of the experiment is to analyze the performance of simple autonomous robots in reaching the point of highest concentration (i.e. the gas leak). This performance has been analyzed for single robots and for cooperating robots using a very simple communication channel