Comparing Visual Servoing Architectures for a Planar Robot

This paper presents a study of three different Visual Servoing architectures for a planar robot manipulator, comparing their behaviour in achieving a desired goal. The studied architectures were 2D Visual Servoing, 21⁄2D Visual Servoing and Visual Servoing by path planning. The target used in the experiments was planar. Four target points were selected as the visual features. Since the robot is planar, has no wrist and the visual features are coplanar, some simplifications could be made in the 21⁄2D Visual Servoing architecture. The other architectures studied were implemented with no simplifications, with the exception of the joint limits potential of the path planning visual servoing. The study presented is based on a 2 d.o.f. planar robot manipulator constructed at Instituto Superior Técnico, and the simulation results were obtained using a Matlab 6.0 Simulink model. The final part of the paper consists in the presentation of the simulation results and the possible conclusions. The paper ends with hints of what remains to be done in the near future.