An Efficient Soft Tissue Characterization Method for Haptic Rendering of Soft Tissue Deformation in Medical Simulation

The modeling of soft tissue behavior is essential in haptic rendering for virtual reality based medical simulators, which provide a safe and objective medium for training medical personnel. This paper presents a measuring device, modeling and effective characterization method of soft tissue´s material properties. Experiments were conducted on five porcine livers using an indentation device and ramp-and-hold trajectory. The soft tissue was assumed to be a continuous, incompressible, homogeneous and isotropic solid and a nonlinear constitutive model based on the observation of the force-displacement behavior of soft tissues. The constitutive model was fitted to the experimental data using the Levenberg- Marquardt optimization algorithm combined with a three-dimensional nonlinear finite element simulation. Scripting software was used to automatically characterize the mechanical properties and to repeat the FE simulation until the simulated and experimental responses matched.