Synergistic robots in surgery-surgeons and robots working co-operatively

Abstract

This paper describes experiments using a new concept in robot surgery; that of a robot with a force control handle moved by the Surgeon. The surgeon back-drives the robot under servo assistance, whilst feeling the force from a rotating cutter during surgery, for example, in total knee replacement. Thus, when machining the knee bones to take a prosthetic metal replacement, the surgeon can use his inherent sensing to slow down, or take a lighter cut, when cuting hard bone. The robot however, can be provided with regions of force constraint so that, say, a flat plane can be cut accurately into the bone to allow the prosthetic implant to be subsequently fitted. At the same time the robot can also be programmed to not allow adjacent regions to be entered, thus preventing damage to features such as ligaments. An experimental system using this active constraint robot (or ACROBOT) for knee surgery is described.

This concept is one of ‘synergy’ between the best capabilities of the robot and those of the surgeon. The robot is able to develop accurate geometry in 3D space, and constrain motions to a safe region, whilst the surgeon can use his innate sensing and judgement to adapt motions and tasks within the pre-defined limits. This ability to adapt procedures in the light of the changing circumstances, makes a synergistic robot concept ideally suited to soft tissue which can move unpredictably when pushed or cut.