Tasks sequencing for visual servoing

Classical visual servoing approaches tend to constrain all degrees of freedom (DOF) of the robot during a task's execution. In this article a new approach is proposed. The key idea is to control the robot with a very under-constrained task when it is far of the desired position, and to incrementally constrain the global task by adding further tasks as the robot moves closer to the goal. A method is first proposed that stacks elementary tasks until the robot is fully constrained. To insure the continuity of the articular velocities when adding constraints, a new control law is then proposed. Experiments that prove the interest of the approach are also provided.