Constraint-Based Soft Tissue Simulation for Virtual Surgical Training

Wen Tang, Tao Ruan Wan
2014 IEEE Transactions on Biomedical Engineering  
Most of surgical simulators employ a linear elastic model to simulate soft tissue material properties due to its computational efficiency and the simplicity. However, soft tissues often have elaborate nonlinear material characteristics. Most prominently soft tissues are soft and compliant to small strains, but after initial deformations they are very resistant to further deformations even under large forces. Such material characteristic is referred as the nonlinear material incompliant which is
more » ... ncompliant which is computationally expensive and numerically difficult to simulate. This paper presents a constraint-based finite element algorithm to simulate the nonlinear incompliant tissue materials efficiently for interactive simulation applications such as virtual surgery. Firstly, the proposed algorithm models the material stiffness behaviour of soft tissues with a set of three-dimensional strain limit constraints on deformation strain tensors. By enforcing a large number of geometric constraints to achieve the material stiffness, the algorithm reduces the task of solving stiff equations of motion with a general numerical solver to iteratively resolving a set of constraints with a nonlinear Gauss-Seidel iterative process. Secondly, as a Gauss-Seidel method processing constraints individually, in order to speed up the global convergence of the large constrained system a multi-resolution hierarchy structure is also used to accelerate the computation significantly, making interactive simulations possible at a high level of details. Finally, this paper also presents a simple-to-build data acquisition system to validate simulation results with ex vivo tissue measurements. An interactive virtual reality-based simulation system is also demonstrated. Index Terms-Nonlinear soft tissue simulation and modeling, virtual surgical training, Robotic-assisted surgery. ! • W. Tang is with the
doi:10.1109/tbme.2014.2326009 pmid:24876107 fatcat:jlq5fs3wujaznkt4nbemrjapo4