Research Of A Cranial And Maxillofacial Puncturing Robot System

Cranial and maxillofacial diseases are affecting the patients’ life seriously, so the effective surgical treatment is an urgent need to solve these problems. Artificial paracentesis is the common diagnostic method in this field, but this method has some inherent shortcomings. At first, the complexity of the operation area demands doctor with rich clinical experience and high professional skills. Secondly, due to the doctor’s visual error in the process of operation, the puncture path deviates preoperative planning,and even causes damage.The use of surgery robot provides an effective way to solve the problem. The robot operation system which assists the doctor in completing puncture operation has not only the general advantages of artificial paracentesis, but also has characteristics such as accuracy, stable operation, convenience and being easy to use. So it has become the research hotspot in the field of the cranial and maxillofacial surgery. In allusion to the hotspot, it is necessary to study the special robot system, navigation, control and so on.This project is under the cooperation with School of Stomatology of Peking University, combined with the surgical experience and the operation, and developed to complete the overall scheme of the surgical robotic system, which is used in the system of the automatic needle in cranial and maxillofacial puncture. In order to achieve flexibility and usability, the hardware design includes the 6-Dof robot, optical localizer,and six-axis force sensor, the software system which includes motion control, spatial adjustment, security mechanism and other module units.This paper researches on its kinematics. Firstly, the method of D-H is used to build the robot mode,and then the forward kinematics and inverse kinematics of the robot has been discussed. Besides, the dynamic model is builded by using the Lagrange equations,the Jacobian matrix has be given by integration vector method and the workspace of the robot has been drawn with MATLAB based on the “Monte Carlo” method.The combination with optical positioning system helps to get accurate calibration of the relationship between robot space and visual space. Three methods are proposed,including the plane measuring method, rotating registration method, the linear and rotary automatic collimation. The precision of registration experiment is carried out to compare these three methods and calibration matrix is developed for final simulation experiment.In order to ensure the safe operation of the surgical robotic system, surgical spaceis divided into three subspaces. Impedance control strategy is introduced to compliant force control in the space of pose adjustment when the contact force exceeds the critical point in the space of pose adjustment, it will back to the starting point quickly in motion buffer space and keep absolute rest in the space of puncturing.At last, experimental study is carried out in the robotics surgical system. Security control has been carried out in three different workspaces, and the result shows the validity of security control mechanisms. In order to verify the practicality of the system,the simulation experiments are carried out to investigate the accuracy, stability and usability, and the result shows that it has the capacity to launch animal experiment.