Takács Árpád, Rudas Imre J, Haidegger Tamás
ABC-iROB, Óbuda University, Budapest, Hungary.
Austrian Center for Medical Innovation and Technology (ACMIT), Wiener Neustadt, Austria.
Med Biol Eng Comput. 2016 Oct;54(10):1553-62. doi: 10.1007/s11517-015-1434-0. Epub 2015 Dec 30.
Rheological soft tissue models play an important role in designing control methods for modern teleoperation systems. In the meanwhile, these models are also essential for creating a realistic virtual environment for surgical training. The implementation of model-based control in teleoperation has been a frequently discussed topic in the past decades, offering solutions for the loss of stability caused by time delay, which is one of the major issues in long-distance force control. In this paper, mass-spring-damper soft tissue models are investigated, showing that the widely used linear models do not represent realistic behavior under surgical manipulations. A novel, nonlinear model is proposed, where mechanical parameters are estimated using curve fitting methods. Theoretical reaction force curves are estimated using the proposed model, and the results are verified using measurement results from uniaxial indentation. The model is extended with force estimation by nonuniform surface deformation, where the surface deformation function is approximated according to visual data. Results show that using the proposed nonlinear model, a good estimation of reaction force can be achieved within the range of 0-4 mm, provided that the tissue deformation shape function is appropriately approximated.
流变软组织模型在现代远程操作系统的控制方法设计中起着重要作用。同时，这些模型对于创建逼真的手术训练虚拟环境也至关重要。在过去几十年中，基于模型的控制在远程操作中的应用一直是一个经常讨论的话题，它为解决由时间延迟导致的稳定性损失提供了方案，而时间延迟是远程力控制中的主要问题之一。本文研究了质量 - 弹簧 - 阻尼器软组织模型，结果表明广泛使用的线性模型在手术操作下并不能代表实际行为。提出了一种新颖的非线性模型，其中使用曲线拟合方法估计力学参数。使用所提出的模型估计理论反力曲线，并使用单轴压痕的测量结果进行验证。该模型通过非均匀表面变形进行力估计扩展，其中表面变形函数根据视觉数据进行近似。结果表明，使用所提出的非线性模型，只要组织变形形状函数得到适当近似，在0 - 4毫米范围内就可以实现对反力的良好估计。
