Time-delay analysis of a robotic stereo active vision system

The time-delay introduced by an image processing system is a crucial factor which plays an important role in the robustness and stability of an active vision system. In this paper, the authors present a feedback control analysis of a stereo active vision platform used to control the pan, tilt and zoom of the active stereo camera. The main goal of the analysis is to determine the maximum time-delay, or delay margin, which can be introduced by the image processing chain without affecting the stability of the overall machine vision system. The proposed procedure considers the investigation of the frequency domain using two indicators of relative stability: gain and phase margin. The obtained delay-margin is used to design the feedback control using the Hermite-Bihler theorem.