Coupled-system stability of flexible-object impedance control

This paper examines the stability of the flexible-object impedance controller when coupled to an arbitrary passive environment. A simple representative system is developed to study the problem based on phenomena observed in a more complex, experimental system. Analysis of this representative system leads to several conclusions regarding factors that limit the achievable impedances of a multi-arm system grasping a common object. The filtering of the external force signals and the effective mass contributed by the manipulators prove to be two of the important factors. Some general guidelines are developed for the successful application of flexible-object impedance control to insure coupled system stability. These guidelines are applied to both the representative and experimental systems and verified