Contact observation of interactive surgical robotics systems

This paper describes a new method to detect the contact position and time/event for force/torque guided robots. The method is of special importance for interactively used robots, because the simple observation of the z-component of the force and its derivative is not sufficient in surgical environments. In these environments an undesired contact of a surgeon with the robot or an excessive change of the guiding force can be misinterpreted by the controller. For surgical applications it is important, that the surgeon can handle the system easily and intuitively. Consequently, in the described approach the system can be controlled by the surgeon by grasping the surgical tool (drilling machine, shaper, or saw) mounted on the manipulator and moving it as usual. In this paper, control schemes are proposed to achieve these features of a robotics system while the surgeon applies at the same time force to the TCP.