A comanipulation device for orthopedic surgery that generates geometrical constraints with real-time registration on moving bones

In this paper, a comanipulation system aimed at providing guidance to bone milling for orthopedic surgery is presented. Contrarily to most existing systems, the proposed approach is able of accounting for eventual movements of the bone with respect to the robot reference base body during the procedure. This property raises from two key components. Firstly, a 3D sensor composed of a camera and a laser projector is mounted on the robot structure in such a way that the milling region can be permanently observed under optimal sensing conditions with a limited risk of occlusions. Secondly, a guide generator running at high frequency interpolates the low frequency data obtained from the sensor in order to generate guiding forces. The paper first provides a presentation of the overall design, with details on the sensing system and the control law. Then, preliminary experiments involving a simplified task emphasize the ability of the system to increase the precision of a subject who is asked to follow a moving environment.