Real time active visual reconstruction using the synchronous paradigm

In this paper, we apply the synchronous approach to real time active visual reconstruction. It illustrates the adequateness of SIGNAL, a synchronous data flow programming language, for the specification of a system dealing with various domains such as robot control, computer vision and the programming of hierarchical parallel automata. More precisely, our application consists in the 3D structure estimation of a set of geometrical primitives using a camera mounted on the end effector of a six dof robot. At the level of camera motion control, the visual servoing approach is specified and implemented in SIGNAL as a function from sensor inputs to control outputs. The 3D reconstruction method is based on the “structure from controlled motion” approach. Its specification is made in parallel to visual servoing. We also present a perception strategy for connecting up several estimations, using time intervals and hierarchical structures for task preemption in SIGNAL. The integration of these techniques is validated experimentally by their implementation on a robotic cell