Stability of cooperative teleoperation using haptic devices with complementary degrees of fr

In bilateral teleoperation of a dexterous task, to take full advantage of the human's intelligence, experience and sensory inputs, a possibility is to engage multiple human arms through multiple masters (haptic devices) in controlling a single-slave robot with high degrees-of-freedom (DOF); the total DOFs of the masters will be equal to the DOFs of the slave. A multi-master/single-slave cooperative haptic teleoperation system with w DOFs can be modelled as a two-port network where each port (terminal) connects to a termination defined by w inputs and w outputs. The stability analysis of such a system is not trivial because of dynamic coupling across the different DOFs of the robots, the human operators and the physical or virtual environments. The unknown dynamics of the users and the environments exacerbate the problem. The authors present a novel, straightforward and convenient frequency-domain method for stability analysis of this system. As a case study, two 1-DOF and 2-DOF master haptic devices are considered to teleoperate a 3-DOF slave robot. It is qualitatively discussed how such a trilateral haptic teleoperation system may result in better task performance by splitting the various DOFs of a dexterous task between two arms of a human or two humans. Simulation and experimental results demonstrate the validity of the stability analysis framework.