Tool guidance using a compact robotic assistant

Surgical robots in popular clinical use are generally large machines, which limits their practical use to some extent. This study aims to investigate the potential of a small, table-mounted robot for tool guidance in minimally invasive surgery (MIS). In particular, its multipurpose use for guidance of various tools was investigated. A compact robot capable of manipulating MIS tools was designed and built. The robot can move in four degrees of freedom (DOF): three rotational and one translational. These DOF correspond to motion constrained by a trocar. The robot kinematics are based on a bevel-geared "spherical mechanism," which allows trocar-constrained motion using a small mechanical device. The robot was tested in a porcine model by manipulating scopes and robotic grasping tools using a joystick as directed by a surgeon. Holding a laparoscope, the robot provided superior stability as a camera assistant. It manipulated the scope for visualization of the liver, spleen, bowel, etc. during manual tissue manipulation. Its compactness allowed increased space around the operating table, and the robot was in fact manipulated by joystick from across the room. Maneuvering grasping tools, the robot similarly provided a stable and dexterous platform for tissue manipulation. The test results suggest that the use of robotics for surgery may be enhanced via compact devices to include more hybrid robotic-manual procedures. The robot motion is smoother and more repeatable than that of a human operator. Use of a foot joystick could also place camera control directly with the surgeon. Flexible endoscopes can also be used with the robot for highly dexterous visualization. Notably, changing tools with this system is a very straightforward process and can be achieved without re-registration of the robot's position/orientation. Therefore, combined with other simple robotic tools for grasping, cautery, etc., compact robotic systems based on this technology could replace the large systems in current use, potentially increasing the impact of robots on medical care. This represents an important step towards multifunctional compact surgical robots.