基于悬臂梁模型的针挠曲预测

Needle deflection prediction based on projecting beam model

目的分析针穿刺组织过程中的挠曲量和穿刺针受力情况,提高针穿刺精度。方法搭建包括工业相机、步进电机和光源等组成的测量设备。用针轴直径分别为1.3、0.9、0.6 mm的穿刺针进行针穿刺软组织实验,利用力传感器得到不同穿刺速度(5、10和15 mm/s)下的穿刺力,通过数字图像处理得到穿刺针的挠曲量。在分析针受力的基础上,构建预测针挠曲量的悬臂梁模型。结果利用悬臂梁模型对直径为1.3、0.6 mm穿刺针在5 mm/s速度下的挠曲量进行预测,其绝对误差小于0.5 mm,相对误差小于10%。结论所建模型能够实现对针穿刺挠曲的预测,可以为机器人辅助柔性针穿刺路径规划和避障运动提供参考。

Objective To analyze deflection and forces of needle insertion and improve the inserting accuracy. Methods The measuring equipment was constructed with industrial camera, stepping motor and light source. The experiment of needle insertion into soft tissues was conducted with puncture needles having different diameters （1.3, 0.9, 0.6 mm）, and the inserting forces at different puncture speeds （5, 10 and 15 mm/s） were measured by the force sensor. The needle deflection was obtained by digital image processing method. Based on the analysis of needle inserting forces, a projecting beam model was structured to predict the needle deflection. Results The deflections of puncture needles with diameters of 1.3 and 0.6 mm at puncture speed of 5 mm/s were predicted by using the projecting beam model. The absolute error was less than 0.5 mm, and the relative error was less than 10%. Conclusions The proposed model can predict the needle deflection effectively, which will provide references for the robot-assisted needle insertion.