Mahvash Mohsen, Voo Liming M, Kim Diana, Jeung Kristin, Wainer Joshua, Okamura Allison M
Mechanical Engineering Department, The Johns Hopkins University, 223 Latrobe Hall, 3400 North Charles Street, Baltimore, MD 21218 USA.
IEEE Trans Biomed Eng. 2008 Mar;55(3):848-56. doi: 10.1109/TBME.2007.908069.
Modeling forces applied to scissors during cutting of biological materials is useful for surgical simulation. Previous approaches to haptic display of scissor cutting are based on recording and replaying measured data. This paper presents an analytical model based on the concepts of contact mechanics and fracture mechanics to calculate forces applied to scissors during cutting of a slab of material. The model considers the process of cutting as a sequence of deformation and fracture phases. During deformation phases, forces applied to the scissors are calculated from a torque-angle response model synthesized from measurement data multiplied by a ratio that depends on the position of the cutting crack edge and the curve of the blades. Using the principle of conservation of energy, the forces of fracture are related to the fracture toughness of the material and the geometry of the blades of the scissors. The forces applied to scissors generally include high-frequency fluctuations. We show that the analytical model accurately predicts the average applied force. The cutting model is computationally efficient, so it can be used for real-time computations such as haptic rendering. Experimental results from cutting samples of paper, plastic, cloth, and chicken skin confirm the model, and the model is rendered in a haptic virtual environment.
对生物材料切割过程中施加在剪刀上的力进行建模，有助于手术模拟。以往用于剪刀切割触觉显示的方法是基于记录和重放测量数据。本文提出了一种基于接触力学和断裂力学概念的分析模型，用于计算在切割材料板时施加在剪刀上的力。该模型将切割过程视为一系列变形和断裂阶段。在变形阶段，根据由测量数据合成的扭矩-角度响应模型乘以一个取决于切割裂纹边缘位置和刀片曲线的比率来计算施加在剪刀上的力。利用能量守恒原理，断裂力与材料的断裂韧性和剪刀刀片的几何形状相关。施加在剪刀上的力通常包括高频波动。我们表明，该分析模型能够准确预测平均作用力。该切割模型计算效率高，因此可用于诸如触觉渲染等实时计算。对纸张、塑料、布料和鸡皮样本进行切割的实验结果证实了该模型，并且该模型在触觉虚拟环境中进行了渲染。
