渐进式内窥镜形状的感知和重建

Deformation sensing and incremental shape reconstruction for intelligent colonoscope

给出并分析了一种内窥镜镜体形状感知系统,特别是给出了曲率传感头的检测原理,及介入装置和控制子系统的设计。将中心波长为1539.234nm和1538.882nm的两根布拉格光纤光栅(FiberBraggGrating)封装在细径基材上,构成直径为3mm应变测量传感器。在介入装置作用下,传感器沿内窥镜活检钳道按平均速度30mm/s间歇式推进,并在介入过程中,每隔50mm等间隔距离采样传感器上的Bragg波长变化值,推算出各点的应变和空间曲率信息。最终运用基于离散点曲率信息的空间曲线拟合方法重建内窥镜镜体的空间形状。实验结果表明:系统原理的可行性,对圆形实验模型的测试表明,传感器插入1000mm后其末端在x、y和z方向上的误差分别为0.5mm、0.8mm和-3.4mm。同时也表明:介入人体的肠道内窥镜形状显示可极大地提高内窥检查安全性。

This paper analyzes a shape detecting system for colonoscope, especially gives the detecting principle of a curvature sensor, the design of an inserting device and its control system. Two Fiber Bragg Gratings (FBGs) with central wavelength of 1 539.234 nm and 1 538.882 nm are mounted on a cylindrical slim string, which compose a detecting sensor with a diameter of 3 mm. The string sensor moves step by step along the biopsy channel by the inserting device, the average velocity of which is 30 mm/sec. In the insertion process, the data of the Bragg wavelength change on the sensor is picked up every 50 mm of insertion and memorized at equidistance points, on which the space curvature information is calculated. At last, the shape of the colonoscope is reconstructed by the use of the space curve fitting method, which is based on curvature information of discrete points. The experiment results verify the proposed shape reconstruction method is effective and efficient. Experiment with a circular model shows that the far end positioning error is 0.5 mm, 0.8 mm and -3.4 mm for x, y, and z directions, respectively, while inserting 1 000 mm sensing string. The display of the colonoscope shape inside human body will greatly increase the inspection safety during colonoscopy operation.