Research On Bilateral Control Of Master-slave Robotic Spinal Surgical System And Temperature Field In Bone Grinding

With the development of robotic technology and the increasing social needs,the medical robotic systems are becoming a hot research area at home and abroad.Taking advantage of human intelligence and the high stability of robot,the master-slave robotic surgery system is receiving abroad attention and research.This paper built a master-slave robotic spinal surgery system for the vertebral plate grinding in the decompressive laminotomy,and a new master-slave workspace mapping method is put forward to realize the master-slave motion control.Furthermore,the temperature field in the process of bone grinding is studied experimentally.Based on the demand of vertebral plate grinding operation as well as the comprehensive analysis of bilateral control method,the direct force feedback control method is adopted to build a master-slave robotic spinal surgery system,the system mainly includes the main manipulator Omega.6 force feedback device,slave robotic arm,visual feedback system,force feedback system and grinding system.The distributed control method is adopted and the master-slave interaction feedback control is completed by writing control program in the upper computer.To solve the dissimilarity in the kinematics and workspace volumes of master and slave devices,a new workspace mapping method is proposed.The master-slave motion is divided into locating movement and fine operation.Positioning movement is under rate control,so that the drill can be moved quickly to surgical areas.Fine operation is under position control,and the operation accuracy is improved with reasonably selected proportion coefficient.To verify the rationality of the proposed master-slave workspace mapping strategy,it is simulated with pseudoinverse method in the V-REP emulator.Actual master-slave motion control is implemented based on the external kinematic function library in V-REP.Master-slave motion control experiment shows that slave arm can follow master manipulator efficiently.Comparing the bone grinding effect,it is concluded that the grinding operation with force feedback has a lower risk than without force feedback.Grinding heat can cause damage to the bone tissue and peripheral nerve in the process of bone grinding,the heat distribution problem in the process of grinding is considered as a three dimensional unsteady heat conduction problem with moving heat source.With the help of infrared thermal imaging instrument,grinding cortical bone experiment is carried,and the temperature rise of bone,the distribution of grinding heat as well as the influence of feed rate on the grinding temperature under dry grinding condition are studied.In addition,the measurement point in infrared image is selected by the way that the actual measurement point is heated with heated probe tip.Experimental results show that the highest temperature in the grinding zone should be controlled within a certain range in the operation to achieve security operation.