Comparison of Teleoperator Control Architectures for Palpation Task

This work focuses on the design and testing of teleoperation controllers which are required to discriminate changes in compliance, addressing the question of which controller architecture performs the best in the high fidelity application of telesurgery. Three teleoperator controller architectures are compared for their ability to detect objects in compliant environments. These architectures are: position error based force feedback (PERR), kinesthetic force feedback (KFF), and position and force feedback (P+FF). The gains for each controller are chosen based on stability, tracking performance, and fidelity of the system. Stability is determined by a robust stability criterion. A sensitivity function is used to determine a tracking criterion. A new fidelity measure is introduced which looks at the sensitivity of the transmitted impedance to changes in the environmental compliance. Experiments are conducted to determine which control architecture allows the operator to most easily determine a change in compliance. This experimental task is designed to mimic palpation of soft tissue performed in medical procedures. The results suggest that the hybrid controller (P+FF) outperforms both PERR and KFF.