Design And Research Of A Laser Robot For Tooth Preparation

Tooth preparation is a common basic operation in clinical restoration.The traditional method of tooth preparation is to cut the target tooth by handpiece.There are many problems with the traditional method,such as low accuracy,high noise,and it is prone to cause iatrogenic injury.Using laser robot for tooth preparation to prepare teeth can take advantage of digital technology and laser technology to solve the above shortcomings.There are a series of problems with the existing laser system for tooth preparation,such as the inability to achieve volume cutting,low processing accuracy,poor monitoring effect,long Z-direction positioning time and so on.In order to solve the above problems,a new generation of tooth preparation robot was designed in this paper.The optical system,mechanical structure,positional inverse equation of galvanometer control,machining error model,and control strategy of voice coil linear motor were studied systematically.Base on the three-axis scanning system,the non-telecentric scanning system was adopted in the optical system,which made the main light incline to a certain extent and avoided the occurrence of light blocking.The volume cutting method was achieved by this way.The simulation model of optical system was established in Zemax software,and the feasibility of the scheme was verified.The plano-convex lens used a new installation method of plane incidence,which improved the performance of the optical system and reduced the aberration.The mechanical structure system adopted the idea of integrated design,which reduced the number of parts and assembly steps.As a result,the accuracy of the mechanical system was improved.The design of the tooth axis finder solved the problem that the tooth fixture cannot locate on the target tooth.The tooth axis finder determined the long axis of the tooth by clamping the contour surface of the tooth.The monitoring module adopted the design scheme of endoscope-mirror-dichroic mirror,which miniaturized the monitoring system,provided auxiliary light source,and improved the image effect.To improve the processing accuracy of laser robot for tooth preparation,the reason of image distortion was analyzed and the software implementation method of compensation algorithm for image distortion was given.It was proved that the algorithm could achieve good correction effect.In addition,the effect of scanning mirror offset was analyzed,and a solution to this issue using a virtual spindle was proposed.In order to solve the problem of long positioning time and poor steady-state accuracy of Z-direction positioning system,the control strategy of voice coil motor was studied.Feedforward control and fuzzy control basing on three-loop control were adopted to control the voice coil motor.The simulation results of MATLAB showed that better control performances could be obtained.The design of the new generation of laser robot for tooth preparation has solved some key problems that need to be solved in clinical application and laid a foundation for further improvement of laser tooth preparation robot.It will accelerate the process of laser robot for tooth preparation replacing traditional tooth preparation methods.