Analysis of stability and performance of telesurgical systems

Abstract

Telerobotic surgical systems, although researched quite extensively, still have stability and performance issues. This is mainly because little consideration has been given to the effect of hardware or environment characteristics as well as practical surgical constraints in previous stability and performance analyses. This work focuses on the stability aspect in greater depth by considering the effect of surgical soft-tissue environments and the damping of the master device and hence, employs passivity approach which relates the haptic device damping with the environment characteristics. There have been a few models proposed to describe the visco-elastic behavior of soft tissues, including the popular Maxwell and Voigt models. Choosing a best soft-tissue model is still unresolved. This research provides passivity analysis of teleoperation of soft tissues, based on the Kelvin model that can overcome the disadvantages of the Maxwell or Voigt models. The passivity analysis results in new criterion for design of the haptic interface as well as the control. The effect of discretization method on the passivity criteria is also discussed. Simulation results show that this newly developed criterion increases the domain of environments that can be passively interacted by the haptic master. This newly developed criterion is, therefore, a less conservative criteria than that developed based on the popular Voigt environment model, which signifies that less device damping is required to maintain the passivity of the teleoperation system which would in turn increase its performance. Another important issue in the performance of telesurgical systems is the practical constraint of force feedback because it is difficult to use force sensors in surgical environments. This is because of the inherent noise, and limitations in the sensor-deployable place and space. A scheme to replace the direct use of force sensors in the slave side may alleviate this problem. This work, hence, ...