基于几何逼近法的斜尖柔性穿刺针运动学研究

Geometric approximation approach based research on kinematics of bevel-tip flexible needles

为了使得斜尖柔性穿刺针能够精确刺中目标靶点,建立斜尖柔性穿刺针的正逆向运动学模型.大量实验研究表明,柔性穿刺针在穿刺过程中,弯曲曲率近似常量沿着由固定半径的圆弧组成的路径进针.基于柔性穿刺针这种特性,利用D-H(Denavit-Hartenberg)参数法建立柔性穿刺针正向运动学模型;利用D-H参数法以及几何逼近法,基于针尖相对靶点的可达性条件,建立柔性穿刺针逆向运动学模型;通过仿真实验验证了所建立的柔性穿刺针运动学模型,结果表明,采用提供的运动学模型能够准确求出从进针点到靶点的所有路径.

The forward and inverse kinematical models were established in order to accurately insert the bevel-tip flexible needle into target.Lots of experimental studies indicate that the binding curvature of flexible needles is approximately constant in the procedure of insertion,so the needle is inserted into soft tissue along apath composed of circular arcs of approximately constant radius.This feature of flexible needles was used.D-H（Denavit-Hartenberg）method was adopted to establish the forward kinematics model of flexible needles.The combination of D-H method and the geometric approximation approach were used to derive the inverse kinematics model of flexible needles under the consideration of the needle tip＇s reachability corresponding to target.The simulation results show that the proposed kinematics model can correctly obtain all feasible paths between the entry point and target.