基于质点—弹簧体模型与改进欧拉算法的力反馈

Force Feedback Based on Mass-spring Volume Model and Improved Euler Algorithm

基于SensAble公司的PHANTOM力反馈设备,以肝脏组织为对象,对虚拟手术仿真中软组织的形变和触觉反馈进行研究。考虑虚拟手术仿真对精度和实时性的要求,采用基于四面体的质点—弹簧体模型构建肝脏组织物理模型,较好地反映了肝脏形变的体特征,增加了模拟的真实感;传统的模型中通常采用线弹性弹簧,但考虑到软组织形变时的黏弹特性,采用弹簧和阻尼器并联的Kelvin黏弹性力学模型模拟肝脏组织的生物力学特征,力图提高形变仿真的准确性。由于光滑的触觉反馈对实时性有更高要求,为进一步提高计算效率,提出一种改进的欧拉算法,仿真结果表明,帧速大于1000HZ,满足虚拟手术实时性需要。

Based on the liver, some research about soft tissue deformation and tactile feedback in the virtual surgery simulation were done using the PHANTOM force feedback device produced by the SensAble Inc. Taking into account the accuracy and real-time performance, the mass-spring volume model based on tetrahedral topology was selected to make the physical model of the liver. It reflected the deformation characteristics of the whole liver better and increased the precision. In traditional models, there were always linear elastic springs. Considering the sticky elastic characteristics of soft tissue deformation, the Kelvin viscoelastic mechanical model was used to imitate biomechanical characteristics of the liver and improve the accuracy of deformation, in which springs and dampers connected in parallel. In order to improve the computational efficiency, an improved Euler algorithm was proposed. The simulation results show that the update rate is more than 1000 HZ and it meets real time performance.