Background: The complex anatomical structure, limited field of vision, and easily damaged nerves, blood vessels, andother anatomical structures are the main challenges of a cranio-maxillofacial (CMF) plastic surgical robot. Bearing thesecharacteristics and challenges in mind, this paper presents the design of a master-slave surgical robot system with a forcefeedback function to improve the accuracy and safety of CMF surgery.

Methods: A master-slave CMF surgical robot system based on force feedback is built with the master tactile robot andcompact slave robot developed in the laboratory. Model-based master robot gravity compensation and force feedbackmechanism is used for the surgical robot. Control strategies based on position increment control and ratio control areadopted. Aiming at the typical mandibular osteotomy in CMF surgery, a scheme suitable for robot-assisted mandibularosteotomy is proposed. The accuracy and force feedback function of the robot system under direct control and masterslavemotion modes are verified by experiments.

Results: The drilling experiment of the mandible model in direct control mode shows that the average entrance pointerror is 1.37+/-0.30 mm, the average exit point error is 1.30+/-0.25 mm, and the average posture error is 2.27+/-0.69 degrees. The trajectory tracking and in vitro experiment in the master-slave motion mode show that the average position followingerror is 0.68 mm, and the maximum force following error is 0.586N, achieving a good tracking and force feedbackfunction.

Conclusion: The experimental results show that the designed master-slave CMF robot can assist the surgeon in completingaccurate mandibular osteotomy surgery. Through force feedback mechanism, it can improve the interactionbetween the surgeon and the robot, and complete tactile trajectory movements.