Soft tissue modeling method based on position constraint and nonlinear spring

Abstract

The invention discloses a soft tissue modeling method based on position constraint and a nonlinear spring. The method comprises the following steps: (1) constructing a soft tissue model formed by tetrahedron units formed by the nonlinear spring and a virtual body spring; (2) simulating the deformation behavior of the soft tissue model; (3) estimating the approximate position of each node, judging whether the state of a node constraint equation is changed or not, wherein constraints comprise spring length and curvature constraints; if the initial state of the equation is changed, correcting the node to a correct position within a reasonable range; if the initial state of the equation is not changed, indicating that the nonlinear spring and the virtual body spring simulate the deformation effect of the soft tissue; and (4) ending the single-step iteration of deformation calculation, and entering the next cycle. The non-linear spring system and the virtual body spring are adopted to simulate the biomechanical characteristics of the soft tissue, a new constraint equation is adopted to limit node displacement so as to enhance the stability of the model, and the defects that a traditional mass spring model is poor in accuracy and unstable are overcome.

Description

technical field [0001] The invention belongs to the technical field of soft tissue deformation model modeling, in particular to a soft tissue modeling method based on position constraints and nonlinear springs, which is used to solve the problem of soft tissue modeling in virtual surgery experiments. Background technique [0002] Virtual surgery is an important surgical assistant training system that can realistically simulate the surgical environment in a low-cost mode. Virtual surgery can not only provide users with visualization needs, but also make doctors familiar with the use of surgical instruments and accumulate surgical skills. At present, a complete virtual surgery system should meet three requirements: real-time, accuracy, and stability. Soft tissue modeling is one of the core modules in virtual surgery, and the fineness of the model plays a decisive role in the reliability of the system. [0003] Soft tissue modeling methods mainly include geometric modeling an...

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Problems solved by technology

[0006] However, the traditional MSM still has defects (a supporting ball spring model for soft tissue deformation simulation, Computer Application and Software, 2013 (01): 109-112): 1. The accuracy of the model is closely related to the spring coefficient, and the coefficient The size is usually determined only by experience; 2. The mechanical principle of traditional MSM is based on Hooke's law, so it cannot accurately simulate the biological characteristics of biological soft tissues, such as nonlinearity, volume retention, etc.

3. The calculation results of differential equations bring inevitable errors, which affect the accuracy and stability of the model

However, none of their solutions completely solve the defects of the above-mentioned traditional models

[0008] To sum up, due to the complexity of human soft tissue structure, the modeling method of soft tissue model has always been a key and difficult part of the virtual surgery system, and currently there are few soft tissue modeling methods that can meet the realistic needs of virtual surgery

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