Keywords: Control , FIDELITY MEASURE, Bilateral Control Design, Haptics, Telemanipulation of Soft Objects, Teleoperation

In this paper, teleoperation controller design for haptic exploration and telemanipulation of soft environments is studied. First, a new measure for fidelity in teleoperation is introduced which quantifies the teleoperation system?s ability to transmit changes in the compliance of the environment. This sensitivity function is appropriate for the application of telesurgery, where the ability to distinguish small changes in tissue compliance is essential for tasks such as detection of embedded vessels. The bilateral teleoperation controller design problem is then formulated in a task-based optimization framework as the optimization of this metric with constraints on free space tracking and robust stability of the system under environment and human operator uncertainties. The control design procedure is illustrated with a case study. The analysis is also used to evaluate the e.ectiveness of using a force sensor in a teleoperation system.

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The teleoperator van be modeled as a two-port network elemetn relating force and position of the master manipulatorto the slave manipulator.

The control design is formulated as the optimization problem of finding the controller values which optimize the fidelity og the teleoperation system with constraints on stability and tracking.

!!! The choice of fidelity metric is based on experiments in human perception of compliant surfaces by Dhruv and Tendick [14].A lthough human subjects are poor at distinguishing the relative compliance of two surfaces (just noticeable di.erence of 14?25%), they can be very sensitive to changes as they haptically scan across a surface. In these experiments, compliance in the vertical direction was varied sinusoidally across a virtual simulated horizontal surface displayed with a haptic interface.As subjects scanned the surface, the spatial variation in compliance was converted to temporal oscillation. As temporal frequency increased, subjects? sensitivity to compliance variation improved to better than 1% just noticeable di.erence due to human vibration sensitivity.
!!! Consequently, the measure of .delity proposed in this paper is the sensitivity of the transmitted impedance to changes in the environmental impedance.

PERR, KFF, P+FF controllers are compared