Haptic Effects of Surgical Teleoperator Flexibility

Abstract

Minimally invasive surgery systems typically involve thin and cable-driven surgical instruments. This introduces link and joint flexibility in the slave robot of a master-slave teleoperation system, reducing the effective stiffness of the slave and the transparency of teleoperation. In this paper, we analyze transparency under slave link and joint flexibility (tool flexibility). We also evaluate the added benefits of using extra sensors at the tip of the flexible robot. It is shown that tip velocity (or position) feedback improves free-space position tracking performance in the presence of robot flexibility. Also, when the interaction forces with an environment are measured by a force sensor and fed back to the user’s hand, tip velocity feedback improves hard-contact force tracking performance. During a hard contact task, tip velocity feedback can also eliminate the transmission of robot flexibility to the user’s hand. Parts of this research have previously been published as M. Tavakoli, R.D. Howe, The Effect of Joint Elasticity on Bilateral Teleoperation, In Proceedings of the 2007 IEEE/RSJ International Conference on Intelligent Robots & Systems, pp. 1618-1623, San Diego, CA, 2007, and as M. Tavakoli, R.D. Howe, Haptic Implications of Tool Flexibility in Surgical Teleoperation, In Proceedings of the 16th Symposium on Haptic Interfaces for Virtual Environments & Teleoperator Systems, pp. 377-378, Reno, NV, March 2008.