PERFORMANCE OF A SIX-AXIS HANDHELD MICROSURGICAL ROBOT WITH ULTRASONIC LINEAR MOTORS

This paper describes the performance of an active handheld microsurgical instrument which uses ultrasonic linear micromotors to actuate a Gough-Stewart platform. The procedure used to linearize the motor response is presented. Given the stall force of the motors, the dimensions of the manipulator have been optimized for the loads expected during vitreoretinal microsurgery. A prototype has been built with a base diameter of 25 mm and a height of 50 mm. The specified workspace for the tool tip is a cylinder 4 mm long and 4 mm wide, when pivoting about a remote center of motion. Experimental results demonstrate a bandwidth of approximately 40 Hz, with position error of less than 0.010 mm RMS in the center of the workspace, increasing to more than 0.025 mm RMS at the limit of the specified workspace. The micromanipulator tolerates transverse loads up to 0.2 N at the remote center of motion.