A New Hybrid Soft Tissue Model for Visio-Haptic Simulation

A new hybrid soft tissue model, which is mainly based on the mass-spring model (MSM) and the 3-D finite strain nonlinear anisotropic elasticity theory, is presented for visio-haptic simulations, such as surgery simulators. One significant difference from conventional MSMs is that the internal forces among mass nodes are derived within the framework of nonlinear continuum mechanics. As a result, the new hybrid model is much more realistic in the sense that it incorporates the typical biological properties and behaviors of living tissue such as nonlinearity, anisotropy, viscoelasticity, and incompressibility. From the implementation point of view, the proposed model can be regarded as a hybrid of finite-element and MSMs, which enables it to maintain largely the advantage of the MSM, such as a simple architecture, low memory usage, and fast computation. The new model is validated in several benchmark problems, and the results show very good agreement with real experimental data reported in the literature. An example simulating a human kidney is given to demonstrate the capabilities of the proposed model in describing the nonlinearity, anisotropy, viscoelasticity, and incompressibility of typical soft tissue.