Rensselaer Polytechnic Institute, Troy, NY, USA.
Int J Med Robot. 2013 Mar;9(1):58-66. doi: 10.1002/rcs.1429. Epub 2012 Apr 4.
Dynamic lattice-based free-form deformation (FFD) allows efficient simulation of global deformation of complex geometric objects. However, directly imposing a number of position constraints due to contact with a tool is non-trivial since it is an over-determined problem.
This paper extends the FFD to directly impose a number of position constraints for the objects to be embedded in (rounded) cylindrical lattice structures. The position constraints are applied by enabling each surface point to locally deform along the near-normal direction to the surface.
The computational time of the local deformation is independent of the number of constrained points other than finite element method. As a real-time application, the proposed method is applied to colonoscopic polypectomy simulation running at over 60 Hz.
The proposed method allows efficient simulation of the global and local deformations of complex geometric objects while achieving accurate tool-tissue interaction in a realistic and robust manner.
基于动态网格的自由变形（FFD）允许对复杂几何物体的整体变形进行有效的模拟。然而，由于与工具接触，直接施加多个位置约束是非平凡的，因为这是一个超定问题。
本文将 FFD 扩展到直接对要嵌入（圆形）圆柱晶格结构中的物体施加多个位置约束。通过允许每个表面点沿表面的近法线方向局部变形，从而施加位置约束。
除了有限元方法之外，局部变形的计算时间与受约束点的数量无关。作为实时应用，所提出的方法应用于结肠镜息肉切除术模拟，运行速度超过 60Hz。
所提出的方法允许对复杂几何物体的整体和局部变形进行有效的模拟，同时以现实和稳健的方式实现精确的工具-组织相互作用。
