Projection-based force reflection algorithm for stable bilateral teleoperation over networks

The problem of stable force-reflecting teleoperation is addressed where the communication between the master and the slave is subject to multiple time-varying, discontinuous, and possibly unbounded communication delays. A new force reflection algorithm is proposed which improves the stability of the system without decreasing its transparency. Based on an estimate of the human forces provided by a high-gain input observer, the proposed algorithm restricts the reflected force in such a way that it eliminates the motion of the master induced by the force reflection signal without changing the human perception of the environmental force. It is shown that the force reflection algorithm proposed allows to achieve stability of the system for arbitrarily high force-reflection gain and arbitrarily low damping/stiffness of the master manipulator.