基于有限元的套管柔性针穿刺软组织弯曲建模研究

Study on bending modeling of cannula flexible needle inserting into soft tissue based on finite element method

套管柔性针作为柔性针的一个重要分支,与其他传统的柔性针相比,在针体路径矫正、穿刺灵活性以及斜尖转角控制精度等方面具有巨大的优势。为深入研究套管柔性针穿刺机理,建立基于有限元的穿刺弯曲模型。分析软组织的生物力学特性,建立了精确的软组织模型;对套管柔性针穿刺软组织进行受力分析,建立力学模型;在力学模型的基础上,建立套管柔性针穿刺软组织的弯曲模型,进行仿真研究。最后通过实验得到穿刺力-时间曲线和针弯曲变形曲线,并与仿真曲线进行比较。结果表明,仿真结果符合实验穿刺力的变化趋势,系统弯曲误差在2 mm以内,满足医学上的要求,验证了套管柔性针穿刺软组织的力学模型以及弯曲模型的正确性和合理性,为路径规划及控制奠定理论基础。

As an important branch of the flexible needle,the cannula flexible needle has great advantages over other traditional flexible needles in the aspects of needle path correction,insertion flexibility and the control accuracy of bevel tip rotation angle.In order to deeply study the insertion mechanism of the cannula flexible needle,the insertion bending model is established based on finite element method.The biomechanical properties of soft tissue are analyzed and an accurate soft tissue model is established;the force analysis for the cannula flexible needle inserting into soft tissue is carried out and the corresponding mechanical model is established.On the basis of the mechanical model,the bending model for the cannula flexible needle inserting into soft tissue is established and the simulations are conducted.Finally,the force-time curve and the needle bending deformation curve were obtained through experiments,which are compared with the simulation curves.The results show that the simulation result accords with the changing trend of the insertion force obtained in the experiment and the system bending error is within 2 mm,which meets the medical requirements.The results verify the correctness and rationality of the mechanical model and bending model of the cannula flexible needle inserting into soft tissue,which lays a theoretical foundation for the path planning and control.