Enhancement in Operator's Perception of Soft Tissues and Its Experimental Validation for Scaled Teleoperation Systems

This paper focuses on scaled teleoperation systems interacting with soft tissues and presents an optimal control scheme to maximize the operator's kinesthetic perception of remote soft environments while maintaining the stability in macro-micro interactions. Two performance metrics are defined to quantify the kinesthetic perception of the surgeons and the position tracking ability of the master-slave system. Kinesthetic perception is defined based on psychophysics by using two metrics, which relate to the detection and discrimination of stimulus. This paper then employs a multiconstrained optimization approach to get an optimal solution in the presence of the stability-performance tradeoff wherein the objective is to enhance the kinesthetic perception while maintaining the tracking and robust stability for interactions between macro and microworlds. Simplified stability constraints for scaled teleoperation systems are designed based on Llewellyn's absolute stability criterion for the optimization procedure, which provides easy and effective design guidelines for selecting control gains. Experiments with phantom soft tissues have been conducted using scaled force-position control architecture, scaled position-position control architecture, and scaled four-channel control architecture to verify the proposed control scheme. Results prove the effectiveness of this algorithm in enhancing the kinesthetic perception of surgeons for scaled teleoperation systems. Psychophysical experiments were then performed to compare our approach with similar contemporary research methods that further validated its efficacy.