Study On Key Technology On Micro-neurosurgery Platform

With the gradual progress of artificial intelligence in the medicine and surgery fields,the robots can be seen in medical and surgical scenarios more frequently in recent years,performing an assistive role in the surgical or medical application.In the robot-assistive brain tumor resection.The three-dimensional force perception of bipolar forceps is critically important in enhancing human surgeons' perceiving of intraoperative forces,so that can reduce injuries on brain tissues as possible caused by the excessive tool-tissue interaction forces applied by surgeons.However,there are still drawbacks to those studies in practical application in neurosurgical scenarios,because of the complicated surgical environment,the strict limitation on the surgical environment,the request for microsurgery under most surgical occasions,the delicate operations of surgeons' hands.Taking the slim configuration of bipolar forceps into consideration,the intraoperative tool-tissue interaction forces are not easy to be traced in real-time.Therefore,it holds great significance to realize real-time monitoring of the interaction force between the end of the surgical instrument and bio-tissues in quantifying intraoperative force on the tissue,speeding up doctors' learning and training periods,reducing the intraoperative tissue lesions,and improving the outcomes of surgical treatment.This paper mainly discusses the interaction forces between the tips of bipolar forceps and brain tissue in the neurosurgical application and explores technical methods to collect and track the tooltissue interaction forces between tips of bipolar forceps and brain tissues during neurosurgeries.The majority of this paper is arranged as follows: Firstly,the manipulator was designed.With the programs in the computor,a connection between the master site and slave site was built,thus a robotic neurosurgaical system was built.Secondly,the intraoperative function and typical operations of bipolar forceps during surgery were illustrated.Two coordinates at tips of bipolar forceps were established,and typical interaction forces between bipolar forceps and brain tissues were analyzed and described.Forming the strains-forces model of bipolar forceps.By taking the slim and narrow configuration of bipolar forceps intoconsideration,analyzing the force-strain conditions on bipolar forceps with the relevant theories of material elasticity mechanics and cantilever beam,the force perception methods,the optimal location for mounting sensors,and the force perception scheme were determined,the signals from the sensors could also be decoupled in real-time.Bragg grating fiber sensor(FBGs)are in small size and long shape,which make it suitable for the geometric characteristics of bipolar forceps.A sketch model of bipolar forceps was built and imported in Solidworks and the mechanical simulation environment was activated,and the optimal positions under different forces loads within x,y,z directions for mounting sensors can be obtained.Three sensors were mounted on the optimal locations with the greatest strains.On the opposite sides of the prong,a pair of sensors were mounted.Meanwhile,on adjacent surfaces,a couple of these sensors were implemented perpendicularly.Based on the elastic deformation property of materials,once there are forces applied on tips of bipolar forceps,all the installed sensors will feedback corresponding light wavelength signals.The intraoperative force information between tips of bipolar forceps and tissues can be obtained by decoupling the signals from sensors.Finally,The sensor system and the sensor calibration platform were built,and a master-slave teleoperated robot surgery platform was constructed.The experiments were performed on an in-vitro pig brain by the teleoperated robot and the data of sensors were collected in rea-time.Three FBGs were installed at each polar of bipolar forceps.all the sensors were connected with the interrogator.The light wavelength drifts were recorded in the software.The sensor calibration console was set up.The sensor scheme was calibrated to clarify the numerical association between the wavelength drifts and force loads with calibrating forces ranging from 0-1.5 N.During the calibration process,the transfer matrix of the coefficient matrix can be ensured.Therefore,the signals returned from sensors in the practical surgical task can be decoupled.The experiments were performed on in-vitro pig brains by the teleoperating robot system constructed in this paper.According to the observation,the bipolar forceps with force perception modified can perceive interaction forces at a minimum of 0.01 N.The force measuring range of this scheme was set in 0-4 N in experiments.The force measuring resolution of x,y,z axial forces are 0.01,0.03,0.1 N,separately.Operating the mechanical arm to adjust the position and posture of the bipolar forceps,pressing the forceps on the electronic scales with an applied force ranging from 0-1.5 N with the measuring deviation below 5%.