The Establishment Of Virtual Surgery System And Research On Force Feedback Algorithm

Virtual surgery is an important application of virtual reality.Traditional surgical training taking animals or corpses as research object,there are ethical or weaker sense of reality and other limitations,thereby,triggering the research boom of virtual surgery.The virtual surgery system plays an important role in the training of doctors,not only reduces the training time,but also reduces the risk of the surgical procedure.The introduction of force feedback to the virtual surgery system makes the operator feel the force of the collision,thus,the surgical training is more realistic.The main contents of this paper are listed as follows: three-dimensional,collision detection,force feedback and stability.Modeling includes geometric modeling and physical modeling.For geometrical modeling,we use CT data from the hospital,and then three-dimensional reconstruction of scene based on Mimics.The texture is rendered by OpenGL graphics tool.For physical modeling,the deformation is calculated by spring damping model.Point cloud data partitioning is the premise for collision detection,it is organized by octree,which leaf nodes store information such as coordinates,radius,normal vector and color.This information will ensure that we truly reproduce the surgical scene and the surgical process.Collision detection uses the bounding sphere algorithm,and the force is calculated based on the density.This paper builds a realistic virtual surgery system.Stability is an important part of the force feedback in virtual surgery system.Stability and transparency are mutually contradictory.This paper adopts the Maximum Output Force Control algorithm(MOFC)base on the passive theory,which extremely improves the transparency,in the premise ensure of the stability.According to the two-port network structure,the virtual surgery system is decomposed into four cascade subsystems: operators,force feedback devices,the sample holder and virtual organizations.Ensure the stability of the various subsystems,which ultimately makes the whole system stable.Experiments show that the system can be stable in both low stiffness and high stiffness coefficients,and the transparency of system is more than 86%.