Modeling And Application Of Soft Tissue Deformation In Contact And Collision Problem

Since the birth of the computer, it has been applied in every aspect of people's daily life. Computers can be easily seen in the areas from scientific computing to the common entertainment. The development of computer speeds up the integration among different disciplines. Mathematics, physics, biology, medicine and computer science are having close contact now. In recent years, as the fast development of computer science, the field of medicine has an urgent requirement of a virtual surgery system that can perform virtual surgery. This system will be applied to teaching, training, diagnosis, surgical pre-planning and many other areas. A complete medical virtual surgery simulation system involves multiple technologies such as computer graphics, digital image process, human-computer interaction and soft issue deformation computation.Virtual surgery system, as a kind of virtual Reality technology, and the three-dimensional modeling of human soft tissue have become important research topics in Computer Graphics. The study of soft tissue deformation with complex structure is also one of the most challenging aspects in virtual surgery and human-computer interaction systems.In this article, we discuss the requirement analysis and module design of virtual spine surgery system, and propose detailed analysis and experiments on the soft tissue deformation and simulation. The soft tissue in human spine (inter-vertebral disks) has severe non-linear characteristics in contact and collision status. So we focus on discussing the contact Finite Element Method (CFEM) and its improvement in order to achieve a good balance of both accuracy and efficiency of the calculation. In this research, we propose a novel simplified approach to calculate annulus-core structure soft tissue's deformation. It's based on classic contact FEM, combines the accuracy of non-linear model and the efficiency of the simplified model. Experimental results have been given to evaluate the feasibility and efficiency. Besides, it includes the introduction of complex structure three-dimensional meshing algorithm, parallel computing by Graphics Processing Unit (GPU) to accelerate, as well as human-computer interaction technology.The main works and innovation points are described as follows:1. The detailed overview of the FEM, related mechanics theories, and numerical algorithm. Optimize the organization of solution for problems with severe non-linear deformation in the contact and collision status.2. Discussion on different meshing algorithms and the selection among them according to the specific requirements.3. We propose improved and simplified algorithm considering severe contact non-linearity. And with the proper contact vertices approximation, we could increase the efficiency of CFEM solution.4. Optimizing the speed of CFEM calculation with the help of GPU parallel computing.5. We propose a rational mechanism to evaluate the simulation results. And validate the authenticity and feasibility on real human spine data.6. Find a balance between efficiency and accuracy by selecting and combing different meshing methods and adjusting program coefficients, material parameters based on practical experiments.7. Our proposed novel algorithm is successfully applied for human spine surgery simulation. Strain and stress analysis on different structures of the inter-vertebral disks are conducted.