Study Of The Simulation Of Soft Tissue Deformation In Virtual Surgery

With the rapid development of modern science and technology, the computer application field are becoming wider and wider. Virtual surgery is an application of virtual reality in modern medicine. It can present real reappearance of the operation for user by vision and force feed back. It is very useful in surgeon training,surgery prediction and image guided surgery. In this paper, several key techniques existing in virtual surgery system were well studied, including finite element method(FEM) mesh generation,simulation of tissue deformation,high accuracy simulation of tissue deformation in large deformable condition,tissue cut condition,mesh update in tissue cutting and static force condensation.In the aspect of FEM mesh automatic generation, this paper presents counter corner pix FEM mesh automatic generation method. In this method, object was firstly segmented into hexahedrons, and then, based on the property of pixies in each hexahedrons, the hexahedron was partitioned into 21 segment models, each segment model has a unique segment pattern. This method has the ability of generating mesh fast with strong adaptability.For the simulation of tissue deformation, this paper gives the visco-elastic finite element tissue deformation simulate method. This method can simulate the creep property and the relax property in the deformation of soft tissue. By the way of adjusting parameter, it can simulate tissues with different kinds of mechanical property. So using this method, we can simplify the virtual surgery system. This method provides an efficient way for the accurate simulation of the tissue deformation in surgery simulation.In order to improve the accuracy of simulation in the case of large deformation of tissue, we developed a total Lagrange finite element tissue deformation simulate method and update Lagrange finite element tissue deformation simulate method. These methods can increase the accuracy of the simulation of large deformed tissue. They also have great meaning in improving the reality of virtual surgery and make the prediction of surgery more credible.In the study of tissue cut condition, the Mises condition was introduced, which is a kind of plastic deform condition in materials mechanical. Then it was improved by combining with the degree of blade sharp and centralizing of stress. This make the virtual cut more accord with really tissue cut.In the aspect of mesh cut algorithm, this paper presents mesh cut algorithm based on projection. Before cutting, the algorithm projects the vertexes in the tetrahedron under cutting to cut plane, this make the mesh easy for cutting. Compared with other mesh cut algorithm, this method can get more reasonable boundary and the number of vertexes increases less during the...