Designing And Implementation Of Electromagnetic Force Feedback Model Focusing On Virtual Interventional Surgery

With its characteristics of wide application,minimal invasion,obvious efftct and minor complication,Interventional surgery can fix the shortcomings of traditional surgery,which will cause large wound and cannot operate on target organs directly.Thus,it’s a burgeoning method to treat cardiovascular and tumor diseases.However,plenty of preoperative training and animal experiments are needed to accumulate operation proficiency due to its high complexity.Anyway,virtual interventional surgery system provides a convenient and practicable way to gain experience for medical staff depending on the critical force haptic feedback generation technology.This thesis proposed an electromagnetic non-contact force feedback device,which is distinguished from mechanical contact force feedback device to generate the crucial circumferential rotation force feedback by discussing the generation of force haptic feedback in virtual interventional surgery.Completely avoiding the mechanical friction,the electromagnetic force feedback device can make precise control of the force feedback.Furthermore,it can vividly reproduce the clinical operation mode of interventional surgery due to its moving unrestricted in the operation range.In this thesis,the feasibility of the proposed electromagnetic force feedback model is verified from the aspects of theoretical research,modeling and simulation,parameter prediction and practical experiment.The specifi work is as follows:(1)Researching on model design.By analyzing the magnetic field characteristics of the electrified coil and the operation pattern of the interventional surgery,a set of electromagnetic force feedback model and its corresponding working mechanism are designed.The electromagnetic force feedback model consists of electromagnetic coil array and surgical instrument model.The working mechanism of the model is proposed according to the characteristics of the electromagnetic coil array topology and the surgical instruments,which includes the working procedure,the basic operating principle and the optimal current allocation strategy.The working mechanism of the model is analyzed and verified theoretically by electromagnetism and locomotion mechanics.(2)Modeling and finite element simulation.Firstly the copper coil,the permanent magnet and other magnetic parts of the electromagnetic force feedback model are constructed proportionally,then the magnetic induction intensity in the target space,the electromagnetic force on the long cylindrical permanent magnet and the axial rotation torque are calculated by finite element analysis,which can prove the feasibility of the designed electromagnetic force feedback model and the proposed working mechanism.(3)Torque-current prediction.Collect,analyze and process the data produced in the procedure of finite element simulation to train the torque-current prediction model,which is established using neural network and model fusion method.This model can replace the three-dimentional analytical method and finite element analysis to predict the torque-current parameters rapidly and accurately.(4)Experimenting and Debugging.Materialize the electromagnetic force feedback model and debug the whole components based on the system operation sequence.The host computer instruct the coil driving module to generate excitation current,which will create magnetic field.Then measure system delay and the circumferential rotation torque produced by the interaction between the surgical instrument and the magnetic field.The results indicate that the electromagnetic force feedback model advanced in this thesis can reproduce the circumferential rotation force feedback in virtual interventional surgery real-timely and accurately to a certain extent.