Safety tracking motion control based on forbidden virtual fixtures in robot assisted nasal surgery

Traditional nasal surgery requires the doctor's left hand to carry the endoscope and right hand to complete the surgical operation using unstable images, potentially leading to danger due to mental fatigue, which may greatly prolong the operation time. Previously, robots in robot assisted endoscope sinus surgery (RAESS) only used simple linear motion control, lacked a dynamic tracking mechanism, and had no effective safety protection constraints, such as virtual fixtures or real-time force sensors. This paper describes an innovative and secure robotic control strategy for a dynamic automatic tracking endoscope with doctor input based on the mixed constraint of a dual-layer hyperboloid virtual fixture generated by a series of key points around the nasal cavity and a model of the threshold contact force. A tracking control strategy is set up after calibrating the navigation system and motion filtering via a human-machine interaction. Several experiments show that the hyperboloid virtual fixtures can generate an efficient constraint of different robotic motions and that the robot can automatically execute a track mission with high precision. The proposed safety protection method can be easily applied to patients with different nose shapes and greatly improve the quality of surgery.