Laser Beam Steering Along Three-Dimensional Paths

This paper deals with the development of a vision-based control scheme for three-dimensional (3-D) laser steering. It proposes to incorporate a simplified trifocal constraint inside a path following scheme in order to ensure intuitively a 3-D control of laser spot displacements in unknown environment (target). The described controller is obtained without complex mathematical formulation nor matrix inversion as it requires only weak camera and hand-eye calibration. The developed control law was validated in both simulation and experimental conditions using various scenarios (e.g., static and deformable 3-D scenes, different control gains, initial velocities, etc.). The obtained results exhibit good accuracy and robustness with respect to the calibration and measurement errors and scene variations. In addition, with this kind of laser beam steering controller, it becomes possible to perfectly decouple the laser spot velocity from both the path shape and time. These features can fit several industrial applications (welding, micromachining, etc.) as well as surgical purposes (e.g., laser surgery) requirements.