The Research Of Soft Tissue Modeling In Virtual Surgery

Virtual surgery simulation system is a typical application of virtual reality technology in the medical field. It plays an important role in many aspects such as preoperative simulation and learning how to deal with situations that may occur in clinical surgery.Virtual surgery simulation system includes virtual organization modeling, collision detection and force feedback deformation algorithm, this paper expands the theoretical derivation and analysis of these three modules. The main contents include the following aspects:Firstly, it has improved the topology of spring-mass model,with the diamond as the new topology unit. The new topology has improved the calculation precision and the real-time performance. The virtual spring was added onto the new model. It is used to constraint hyperelastic phenomenon caused by excessive force. Meanwhile, the virtual spring is also used to calculate the force feedback. It reduces the complexity of the force feedback calculation.Secondly, after comparing the advantages and disadvantages of different algorithms,on the basis of the real-time and accuracy of collision detection, it selects the bounding sphere and the axial bounding box. And the Delphi software is used to simulate the collision detection. It not only provides the operator an intuitive visual impact, but also observe collision comprehensively. It improves the real-time and the accuracy of the collision detection.Thirdly, in view of the force feedback for the requirement of real-time and calculation of deformation algorithm, the paper proposes a new force feedback deformation algorithm.The algorithm sifts the effective mobile particles of the layers, then calculates the area formed by these particles. The virtual force is calculated with the area, then the external force is equivalent to the sum of the virtual force in the deformation layers. The new algorithm is simple and reduces the deformation calculation of force feedback. It is in conformity with the force deformation process.Finally, considering the object deformation curve is similar to normal distributioncurve, it proposes a new force feedback deformation algorithm. The algorithm adopts an approximate normal distribution function. It reflects the farther distances from the center particle the smaller force in the deformation area. Also it better reflects the linear relationship between force and shape variables in the deformation process. Then, relevant simulation results show the feasibility of the algorithm.