A 3D Collision Handling Algorithm for Surgery Simulation Based on Feedback Fuzzy Logic

A new algorithm for collision handling between 3D agents in a laparoscopic surgery simulator is proposed in this paper. Simulation in minimally invasive surgery pursues a trade off between real-time execution and fidelity in the virtual scene. In order to achieve visual realism, accurate deformations of graphical models are required when interactions between tools and organs occur. Specifically, during the simulation step, vertices of the organ detected as collided must be accurately shifted out of the tool to elude the interpenetration. Techniques reported in the literature usually resort to approaches grounded on physical properties that entail significant computational load. Consequently, it reverts on non-desirable simplifications in which the 3D character of tool models is typically avoided. Hence, the aim of this paper is to present an algorithm for collision handling between 3D deformable (organ) and non-deformable (surgical tool) objects involved in a non-structured interaction scene. The proposed approach obtains the new position of each collided vertex of the organ taking into account two key concepts. First, a parameter which embodies the ongoing state of the scene is obtained making use of both kinematic information of the surgical tool and geometric information of the organ surface that surrounds the vertex under analysis. Second, three parameters inferred from a feedback fuzzy logic system ponderate the nature of the tool motion with respect to the organ, modeled as penetration/extraction and sliding. Preliminary experimental results show that this solution is able to avoid the interpenetration among the multiple colliding points detected in each simulation step in an efficient, physically and spatially coherent manner.