FUNDAMENTAL LIMITS OF PERFORMANCE FOR FORCE REFLECTING TELEOPERATION

The quality of telepresence provided by a force-reflecting teleoperato r is determined,for the most part, by the fidelity of the contact-forc e information fed back to the operator These fed-back forces, however also directly influence system stability, and in this paper we investi gate the relationship between fidelity and stability with a view towar d understanding how stability considerations impose fundamental limits on system performance. The key idea of our work is to draw an explici t distinction between the information conveyed by the force signal and the energy inherent in that signal. Using known physiological propert ies of the operator we argue that there exists a natural partitioning between information and energy wherein information is conveyed at freq uencies above roughly 30 Hz, while the energetic interaction between t he slave and the environment takes place at frequencies below this. We embody this distinction in a two-channel framework that we claim prov ides insight into the design of force-reflecting systems. Using a I-DO F model, we study the effect of various system characteristics, notabl y mass, stiffness, and damping properties, on performance and stabilit y. This model is used to derive expressions for the maximum force-refl ection ratio that guarantees stability against pure-stillness environm ents and to investigate the role of various compensation elements, inc luding local force control around the slave. Finally, a framework is d eveloped for force-reflecting teleoperation that maximizes the force i nformation conveyed to the operator subject to the constraints imposed by stability considerations.