Design and Control of Fully Handheld Microsurgical Robot for Active Tremor Cancellation

This paper presents the design and control of a fully handheld robot for robot-assisted microsurgery. The handheld robot incorporates a miniature 6-PUS parallel micromanipulator that can impose a remote center of motion (RCM) at the incision point of entry during microsurgery. An optimization framework is formulated to determine the geometric parameters of the micromanipulator. The optimization aims to minimize force applied on actuation modules by lateral load at the RCM. The optimization yields a base diameter of 16 mm, a top diameter of 12.6 mm, and a connecting link of 9.4 mm, which offers a cylindrical workspace 4-mm wide and 3-mm high with a 5-mm travel in linear actuation. An order of magnitude higher force capability is attained in the smaller form factor compared to the latest handheld micromanipulator. We built the fully handheld version of the microsurgical robot by incorporating embedded electronics and an EM tracker for sensing the 6-DOF pose of hand motion. The real-time control framework of the handheld robot is also presented, including motion filter for active tremor cancellation. As a result, the handheld robot can tolerate side loads up to 5.0 N for a lateral load applied at the RCM without significant degradation in control. Finally, the robot-aided operation with the active tremor cancellation shows a significant peak-force reduction compared to unaided operation during the task of maintaining contact force.