Research On Soft Tissue Deformation And Collision Detection In Virtual Acupuncture Surgery

Virtual reality technology,as a new science and technology,has ushered in a period of rapid development in recent years,and its application in the medical field has gradually expanded.As a new interdisciplinary research,the virtual acupuncture surgery simulation system is a practical application of virtual reality technology in traditional Chinese acupuncture treatment methods,which has played a great benefit in improving the efficiency and saving the cost of acupuncture training.Soft tissue deformation modeling technology and collision detection technology,as the key technologies of virtual acupuncture surgery simulation system,occupy a large amount of storage space and computing resources in the virtual simulation process,which directly affects the realism and real time of the simulation process,but with the current level of research,the realism and real time requirements of virtual acupuncture surgery simulation system have been in a contradictory state.In order to meet the requirements of realism and real-time in the virtual needle surgery simulation process,this study improves the structure of the spring mass model and optimizes the collision detection algorithm to achieve the purpose of improving the degree of realism and real-time adaptation in the virtual needle surgery simulation process.In the study of soft tissue deformation and collision detection in virtual needling surgery,a virtual milli-needle model with a high degree of simulation and a virtual arm skin model with collision detection experiments need to be established.In the model building stage,two parts need to be completed: first,a virtual geometric model that meets the shape characteristics of the model,and second,a virtual physical model that meets the biomechanical properties of soft tissue deformation.Through the study of soft tissue biomechanical properties,three common geometric modeling methods and six common physical modeling methods are selected to introduce the principles,applicable objects,and advantages and disadvantages,so as to lay the principle foundation for the establishment of virtual soft tissue model.In the construction of the virtual geometric model,different geometric modeling methods were selected for the milli-needle model and the soft tissue model according to the structural characteristics of the virtual model shape,and a composite geometric model based on skin-bone was constructed.In the physical modeling,based on the traditional spring mass model topology,a rhombic spring mass topology with equilateral triangular stabilized surface pieces as the base unit was established and the force analysis was completed to address the problem of poor stability of soft tissue deformation model.At the same time,a comprehensive analysis of the commonly used integration methods for the differential equations of motion of the mass is conducted to select the appropriate integration method and further improve the real-time performance of the deformation simulation.In the construction of the collision detection algorithm,this study combines the specific conditions of various collision detection algorithms and the comprehensive analysis of the deformation characteristics of the virtual model,and finally chooses to establish a hybrid hierarchical envelope box algorithm to achieve effective improvement of the operation efficiency of the collision detection algorithm and improve the real-time performance.In this study,the OBB-Spherical Bracketing Box tree structure is established for the virtual milli-pin model with rigid body nature,and the AABB-Spherical Bracketing Box tree structure is established for the virtual arm soft tissue model with soft body nature,which is combined with the virtual space exclusion method to quickly exclude the virtual environment space areas where collision is unlikely to occur and reduce the non-essential collision detection algorithm operation process.After experiments,the hybrid hierarchical envelope box collision detection process can trigger the soft tissue deformation when the milli-needle model collides with the soft tissue more accurately,and complete the collision detection process based on meeting the requirements of realism and real-time of the virtual needling surgery simulation process.