| With the continuous development of virtual reality technology and augmented reality technology,the combination of the two technologies and medical surgery has produced virtual surgery simulation systems.The virtual surgery simulation system provides users with the reproduction of the real scene of the operation,and users can simulate the real surgical procedure in the virtual environment through the force feedback tactile interaction device to obtain realistic tactile feedback and visual effects.It can be applied to doctors’ surgical planning,intraoperative navigation,postoperative evaluation and surgical training.In the surgical operation,the surgeon usually perceives the soft tissues of the human body through surgical instruments,thus the establishment of the soft tissue physical model is one of the key technologies in virtual surgery simulation system.The mechanical properties of soft tissue have always been restricting the effect of physical model of simulated organs in virtual surgery,and it has become a bottleneck in the development of the accuracy of soft tissue physical models in this system.Therefore,researching the mechanical properties of biological soft tissue and measuring the mechanical parameters of soft tissue play an important role in improving the tactile feedback effect in virtual surgery.Based on the research on the mechanical properties and mechanical parameters of soft tissues at domestic and abroad,in this thesis,an experimental platform for measuring the mechanical properties of soft tissue is built.The soft tissue mechanics model is established by measuring the mechanical parameters of soft tissue,and the model is validated by finite element simulation software.The ultimate goal is to apply the model to the virtual surgical system,and to achieve a closer force feedback effect.The specific work completed is as follows:(1)On the basis of analyzing the mechanical properties of soft tissue,the hyperelasticity and viscoelasticity of soft tissue are mainly studied,and summarizes the main research status and existing models of these two characteristics.By analyzing the material properties of soft tissue and combining experimental data,a hyperelastic model and a viscoelastic model suitable for the research object are proposed.MATLAB software is utilized to analyze the experimental data,combining the data with the model,the model parameters are determined,and the specific model expression is obtained.(2)In order to measure the mechanical parameters of soft tissue,mechanical experimental schemes of soft tissue are designed.In this thesis,porcine liver is used as the research object,the uniaxial tensile and uniaxial compression experiment of porcine liver are designed.In addition,in order to study the viscoelastic properties of soft tissues,stress relaxation experiments and creep experiments are also designed and performed.On the basis of the experiments,the actual mechanical parameters of soft tissue,such as the elasticity coefficient and viscosity coefficient of the liver,are applied to the model.(3)In order to verify the model,ABAQUS finite element simulation software is used to simulate the uniaxial tensile experiment of porcine liver,and then the experimental data of the simulation is compared with the actual measured data. |
