RoMAN-MD: 6 DOF humanoid arm for medical applications

During the last five years, we developed two types of humanoid arms called as RoMAN and RAMeX. RAMeX has been developed for imitating human arm motions with low cost, whereas RoMAN is a high-end humanoid arm module with micrometer precision. The authors have noticed that such humanoid arms and the robotic arms for surgery have a close similarity in their functions and structures. All of them imitate motions of human arms in common. In this paper, we try to evolve the humanoid arms(RoMAN) into the surgical robotic arms(called as RoMAN-MD) by modifying kinematic parameters. The surgical robotic arms differ from the humanoid arms in many detailed aspects such as degree of freedom(DOF), workspace, configuration of multiple arms, control scheme, an end effector. In order to evolve RoMAN into the surgical robotic arm(RoMAN-MD) effectively, RoMAN is reconfigured as a form of module. The module includes all the parts for a robotic arm such as motors and controllers. The original version of RoMAN did not take the modular design into account and was attached to a torso with complicacy. The robotic arm module is very convenient to configure a surgical robot system consisting of several robot arms. The purpose of RoMAN-MD is to perform robotic operations in minimally invasive surgery(MIS) or robot assisted surgery. The degree of freedom(DOF) in RoMAN is five, whereas RoMAN-MD has 6 DOF taking surgeon´s motions into account. As an arm of a humanoid, RoMAN is configured onto a robotic torso in a perpendicular direction to the surface, whereas RoMAN-MD is usually located horizontally with a surgery operating table. With this difference, the workspace of RoMAN-MD is reconfigured as much wider front by changing length of links in RoMAN. Fig. 1 and 2 depicts the change of workspace in RoMAN and RoMAN-MD. Fig. 3 illustrates a teleoperated robotic surgery using two RoMAN-MD and a master device. All the motor units consisting of a motor and a control board are communicated by CAN with - - 1 Mb/s speed. The motors can be controlled in position or velocity or torque mode. The torque mode is useful in the surgical robot because a surgeon guides a path of the robot by a hand and the robot can control its force applied to the operated part. The master device and the robot can be controlled by one PC or by two PC´s via TCP/IP communication. In this paper, the humanoid arms have been evolved into the surgical arms by modifying some design parameters. The modularized surgical arms are easy to be configured in the multiple robot arm system. In the future study, the design parameters such as DOF, workspace, force, end effector and control scheme will be optimized in the typical fields of surgical robotics.