Transforming a surgical robot for human telesurgery

This paper discusses the technology and developments behind transformations made to a commercial robotic surgical system, Computer Motion, Inc.ʹs Zeus(trade mark), in order to make it possible to fully and safely support minimally-invasive human telesurgery performed over very large distances. Because human life is at stake, issues relating to safety, detection of errors, and fail-safe operation are principal in importance. Therefore, it was paramount that all of the safety features of the commercial product Zeus(trade mark) remained intact during this transformation. This paper discusses the commercial robot and its safety features as well as the real-time communications system added to it as part of Operation Lindbergh, the first transatlantic human telesurgery. Particular attention is paid to the limiting effects of latency. Key techniques developed during this project are discussed, including the need to send the full robot state in each transmitted packet rather than incremental or modal data, thereby treating all telecom problems uniformly as dropped packets. The use of hierarchical design (incorporating Zeus as a drop-in component rather than modifying its internals) allowed the project to focus on the new issues arising due to teleoperation while gaining the robust, error checking, and fail-safe aspects of the design from the use of the unmodified commercial robot. The concept of local mode was created and used during initialization and during communications abnormalities and outages in order to keep the local and remote subsystems active and safely quiescent.