Research And Implementation Of Soft Tissue Deformation And Cutting Simulation In Virtual Surgery

Virtual surgery is one of the more representative applications of virtual reality technology and is widely used in the medical field.It has made great strides in surgical simulation training due to its advantages of ease of use,low cost and repeatability.Realistic surgical simulation systems allow operators to seek out surgical simulation experiences in training,thereby improving operator skills and the quality of training.In virtual surgery research,key technical issues such as geometric and physical model construction,deformation and cutting simulation,collision detection,haptic interaction directly determine the realism of the simulation system.This thesis addresses the above key technologies in depth and the main work is as follows:Firstly,to address the huge computational consumption of the complex model in the geometric model construction for the operation of the simulation system,the complex model is simplified based on the QEM edge folding algorithm,and the simplified surface mesh model is divided into constituent body models based on the Delaunay algorithm tetrahedra.On the basis of the geometric model construction,in order to make the model with biomechanical properties.The soft tissue model is constructed by applying a position based dynamics algorithm and adding the corresponding constraints.To ensure the deformation elasticity and stability of the soft tissue model.Through deformation experiments,the soft tissue model is verified to have realistic deformation effects.Secondly,in order to solve the problem of broken surface when cutting the surface model in the cutting simulation,a combination of symmetric movement of cutting points and Bessel curves is used to recreate the incision.In order to solve the problem of unsmooth incisions produced after cutting,the surface incisions were redrawn based on the Bessel curve method to make the incisions more realistic.The feasibility and realism of the method is verified through cutting experiments on soft tissue models.Thirdly,common collision detection methods are investigated.A collision detection method based on an octree hierarchical wraparound box detects whether a collision occurs between a soft tissue model and a surgical instrument,enabling subsequent deformation and cutting simulations.An AABB wraparound box is first added to the target object,and then the nodes of the target object are divided into an octree space to speed up the collision detection process and improve real-time performance.The haptic forces generated in the interaction were investigated in conjunction with force feedback devices,and the force was fed back to the operator through the force feedback devices to realise the haptic sensation and make the simulation more realistic.Through the collision detection experiments between models,the method is verified to be feasible and real-time.Finally,a virtual surgery simulation system that can realise force feedback was built by combining hardware and software.The soft tissue model deformation and cutting simulation experiments were completed,and the time efficiency analysis of the operation effect of the virtual surgery simulation system was conducted.Further verified that the built virtual surgery simulation system meets the realism,real-time and stability of virtual surgery.