Optimal servoing for active foveated vision

Foveated vision and two-mode tracking, as inspired b y the human oculomotor system, are often used in active vision system. The purpose of this paper is t o provide answers to the following basic questions which arise from implementations. First, is it beneficial to have foveated vision and what is the optimal size of the foveal window? Second, is there a need for two control mechanisms (smooth pursuit and saccade) for improved performance and how can one eficiently switch between them? In order to do so, a setup is proposed in which these strategies can be evaluated in a systematic manner. It is shown that the fovea appears as a compromise between the tightness of the tracking specifications and computational constraints. Introducing a model for the later and postulating some a priori knowledge of the target behavior, it is possible to compute the size of the fovea in an optimal way. As a by-product, “smooth-pursuit” can be defined in a natural way, and the use of a two-mode tracking scheme is justified. The second mode , i.e. “saccadic controlN, aims at re-centering the target on the fovea so that the smooth pursuit controller can continue to operate. It is shown that a control strategy can indeed be defined so that this objective can be met under appropriate operating conditions.