Research On Master-slave Control Of Robot-assisted Dental Preparation

Dental caries is a kind of progressive disease of the teeth hard tissues caused by multiple factors in the oral cavity,and the secondary diseases such as pulpitis,inflammation of the alveolar bone and jaw bone seriously affect the oral health of people.As a necessary part of the restorative dentistry treatment,dental preparation means that the dentist grinds the hard tissues of personalized caries to make the tissues left after preparation to form a predetermined preparation for the subsequent installation of metal or porcelain dental crowns and other operations.However,due to the influence of the epidemic,our country has entered a normalized prevention and control stage,while the large number of patients,high population density and mobility of personnel in hospitals make epidemic prevention more demanding.However,during the traditional dental preparation procedure,close contact between the doctor and the patient is inevitable.Therefore,there is a need to introduce master-slave controlled robots to assist in dental preparation procedures in order to complete the surgery in the isolation of doctor-patient space,which not only can effectively prevent and control the spread of epidemic,but also can effectively improve the quality of dental preparation for better treatment results.In this paper,the following research was conducted to address the problems of master-slave control for robot-assisted dental preparation.In this paper,the patient’s caries model is reconstructed by image segmentation of CT data commonly used in dental examination based on Canny operator,and the optimization of the model and the design and generation of dental preparation guides and auxiliary guides are completed by using Geomagic software.To solve the problem of safe interaction of the generated dental preparation guide,the collision detection was proposed to complete the assistance to the physician,and according to the special structure of the guide,a hybrid hierarchical tree surrounding box construction method for the dental preparation guide was proposed,and collision detection between the guide and the dental handpiece was completed.Finally,a virtual guide for the dental preparation that can provide safe interaction to the dentist was obtained.An intraoperative navigation system to assist in dental preparation was constructed,and a marker-based optical navigation method was determined by analyzing the environmental characteristics and surgical requirements of dental preparation.The coordinate system between the devices was constructed by analyzing the roles of each device in the system.The forward kinematic analysis of the UR5 e robot was analyzed,and the coordinate transformation between the end of the robot and its base was determined.Based on the five-point method,the coordinate transformation between the end of the surgical instrument and the gripper was completed,and then the calibration of the surgical instrument was completed.Then,the position of the caries in the navigation system was determined by the contact method,and the registration of the caries was realized,Furthermore,the real-time positioning of the end of the dental handpiece and the patient’s position and posture in the intraoperative navigation system for assisting dental preparation was realized.By combining the forward kinematics analysis of the master robot and the motion analysis results of the slave robot,the workspace of the master robot and slave robot was determined.Then,the position and posture of the slave robot in dental preparation surgery were analyzed.Combined with intraoperative navigation,the limitation of each joint of the slave robot was completed,which reduces the danger of the robot stopping suddenly due to multiple inverse solutions in the master-slave control.According to the development function package of master and slave robots,the secondary development of them was completed.According to the different motion spaces between master and slave robots and the special environment of oral cavity,a variable proportion master-slave control strategy based on the operating space was proposed,and the simulation verification was completed in URSim.In this paper,the experimental platform of the master-slave control of robotassisted dental preparation system was built,and the patient’s mandible,the auxiliary preparation guide and the calibration bracket were printed and formed.The navigation and image data were received by the host computer and the control signals from the master handpiece were sent to the slave handpiece to complete the dental preparation experiment.The accuracy of the robot master-slave control motion under the optical navigator was verified by determining the number of piercings at the end of the dental handpiece and the location of the feature points.The effectiveness of the master-slave control strategy for robot-assisted dental preparation was confirmed by collecting the motion trajectories between the master and slave hands and analyzing their errors to verify the master-slave consistency.The feasibility of the master-slave control system constructed in this paper for robot-assisted dental preparation in dental preparation surgery was verified by robot-assisted dental preparation experiments.