Control of redundant robot arms for human-robot interaction

The new generation of the robot should have the intrinsic ability to share the operating environment with humans. Often physical interaction occurs, and this may happen at any part of the manipulator body. The contact can be either intentional (i.e., required for collaborative tasks), or accidental (i.e., unexpected collisions). To guarantee a safe robot reaction to physical interaction, suitable control strategies must be adopted, which may require the measurement or the estimate of exchanged forces and moments. The problem of controlling the position and orientation, expressed in a singularity-free representation form, of the end-effector of a redundant robot, while addressing an active compliant behavior within the null-space is discussed in here and here. To accomplish the task, a dynamic controller is designed without the need of any exteroceptive sensors information. A rigorous stability analysis is provided to confirm the developed theory.