胶囊内窥镜倾角传感式磁跟踪系统的设计

A Magnetic Sensing and Inclination Sensing System for Wirelessly Tracking Capsule Endoscopy

为了提高胶囊内窥镜的跟踪精度,增强实时性,提出了倾角传感与磁场传感相结合的无线跟踪方法。推导了倾角传感模块在跟踪系统中的角度测量原理,基于坐标旋转和空间磁场理论,建立了倾角传感式磁跟踪数学模型,获得了胶囊方位与磁场信号的数学关系式。根据倾角传感的磁跟踪方案,设计开发了系统样机,包括:磁场发生装置、倾角式无线磁传感模块、无线数据接收装置、数据处理平台。跟踪实验表明,角度跟踪平均误差为4.2°、4.5°,标准偏差为2.2°、2.4°;x分量、y分量、z分量的平均位置误差为0.011 3 m、0.012 1 m、0.010 4 m,标准偏差为0.008 2 m、0.007 5 m、0.006 8 m。倾角传感器的引入减少了励磁源的个数,减小了每轮跟踪的采样数据量和采样时间,简化了非线性方程组的求解,进一步提高了跟踪精度。

In order to further improve the tracking precision and real time performance, a novel tracking method using inclination sensing and magnetic sensing was investigated to non-invasively track a capsule endoscopy in the gastrointestinal tract. First,the principle of angle measurement employing an inclination sensor was analyzed and a rotation angle for tracking is deduced. The prototype of the tracking system was developed based on the tracking principle. The tracking experiment shows that the mean errors of the two rotation angles are 4. 2° and 4. 5°, respectively. The standard deviations of the two rotation angles are 2. 2° and 2. 4°,respectively. The mean errors of x,y and z components are 0. 011 3 m,0. 012 1 m,0. 010 4 m,respectively. The standard deviations of x,y and z components are 0. 008 2 m,0. 007 5 m,0. 006 8 m,respectively. Since the angle was acquired by the inclination sensor,the number of the excitation coils can be reduced. For each position and orientation of the capsule endoscopy,the amount of data and the sampling time decreases. As the unknowns decreases in the tracking nonlinear equations,the tracking precision is improved.