Force-position control for a miniature camera robotic system for single-site surgery

This paper describes the design and implementation of a robotic vision system for single-site surgery. The system is composed of a wireless miniature camera robot with magnetic pan and tilt capabilities, and an external robotic arm to guide the camera along the abdominal wall. The camera robot is provided with a set of magnets, and a magnetic holder is attached at the end effector of the manipulator. This way, the camera robot can be displaced to obtain additional viewpoints of the abdominal cavity by displacing the external manipulator. The first prototype of the camera robot with an embedded LED lighting system is described. To properly displace the robotic arm over the abdominal wall, a hybrid force-position control has been developed, which includes a torque compensation module in order to obtain an appropriate orientation of the end effector. The contact surface has been assumed to be an elastic model, which stiffness matrix is estimated with a recurrent least squares algorithm. Finally, an in-vitro experiment to validate the control scheme proposed is presented.