On the advantages of combining differential algorithms and log-polar vision for detection of self-motion from a mobile robot

This paper describes the design and implementation on programmable hardware (FPGAs) of an algorithm for the detection of self-mobile objects as seen from a mobile robot. In this context, 'self-mobile' refers to those objects that change in the image plane due to their own movement, and not to the movement of the camera on board of the mobile robot. The method consists on adapting the original algorithm from Chen and Nandhakumar [A simple scheme for motion boundary detection, in: Proceedings of the IEEE International Conference on Systems, Man and Cybernetics, 1994] by using foveal images obtained with a special camera whose optical axis points towards the direction of advance. It is shown that the use of log-polar geometry simplifies the original formulation and highly reduces the volume of data to be treated. Limitations of the algorithm due to the differential nature of the approach are discussed, relating them with the parameters of the system. Experiments are shown in which a self-mobile object is detected in several conditions. (C) 2001 Elsevier Science B.V. All rights reserved.