Virtual Surgical Suture Simulation Based On Mass Spring Model

Virtual surgery has far-reaching significance for improving medical education and training patterns and enhancing medical worker’s business level.Virtual surgical suture is a necessary part of surgical simulation.However,the existing simulations of virtual surgical sutures still have some problems such as the poor stability of suture knotting,the poor real-time during the suture simulation,and the difficulty to describe the internal details of the wound.In this paper,a virtual surgical suture simulation platform was implement for handling the hand wound suture process.We did research on suture modeling,knot simulation,and suturing interaction process.The details are as follows:Firstly,a hybrid suture model is presented in this paper.Here,this model introduces the torsion spring and the method of calculating the internal tension on the basis of the mass spring model to simulate the tension inside the suture.In the colliding process of the suture knotting,the maximum displacement limitation of each vertex of the suture is introduced to this model to prevent getting an error collision feedback force.The collision cluster method is also developed in the model to eliminate the phenomenon that tight knots constantly shake.Furthermore,some comparisons between the sutures of hybrid suture model and sutures based on the FTL method are provided.The results show this hybrid suture model not only can complete complex suture knot,but also make the tight suture knot obtain an enough stability.Secondly,in order to improve the efficiency of soft tissue collision detection,a hybrid collision detection algorithm is presented.This method combines the hierarchical bounding box method with the simplified physical model method to reduce the amount of computation.In addition,we proposed a binding force collision feedback algorithm.This algorithm introduces the rebound and the buffer force so that the suture can finally remain stable on the surface of soft tissue in the state of force balance.The collision experiments show that the improved collision detection method can significantly enhance the collision detection efficiency.In addition,the binding collision feedback algorithm can effectively avoid the suture jitter on the soft tissue surface.Finally,we simulated the suture interaction inside the soft tissue.An improved sliding constraint point algorithm is proposed.This method eliminates redundant constraint points and introduces time stamps.By this way,it eliminates the phenomenon that the correspondence between the vertices of the suture and the constraint points cannot be updated correctly.In order to prevent the closed wound from reopening under the action of the soft tissue deformation model,we proposed a visco-elasticity constraint algorithm.This can simulate the viscoelasticity produced on both sides of the closed wound.The suture simulation experiments show that the viscoelasticity constraint algorithm can keep the wound closed.The improved sliding constraint point method enhances the stability of the suture slide within the soft tissue.