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Abstract

During experiments with a dual-stage bilateral teleoperation system proposed in [1], it was observed that flexibilities in the coupling linkage of the fine manipulators and in the structure of the coarse manipulator produce vibrations that can induce instability. The effects of flexible modes on the stability robustness and performance of a bilateral motion scaling system are studied empirically. Performance is examined by comparing the environment impedance to that transmitted to the operator, while stability robustness is evaluated using the multivariable Nyquist test. Difficulties in implementing an effective active damping control with endpoint feedback are then discussed. They can be traced mostly to inaccuracies in modeling and/or sensing and actuation. The approach of passive damping is investigated in detail. The constrained layer damping technique is proposed to achieve intrinsic structural damping. The stress/strain analysis based on the Strain Energy Method first proposed by Ross, Ungar and Kerwin [2] is summarized and explained. The extension of this analysis to a hollow beam with multiple viscoelastic laminates is developed and simulation results are presented. Experiments were performed with a hollow cantilever aluminum beam with multiple damping layers, and the computed damping coefficients were compared to the measured ones.