基于IMU的C形臂旋转角度定位方法的研究

Rotational angle of the C-arm positioning method based on the IMU

目的移动式X线透视影像设备(C形臂)凭借其便携、实时的优势已成为图像引导手术中标准配置设备,然而大部分医院配备的C形臂不具备旋转角度测量功能。方法本文设计了一种基于惯性测量单元的C形臂旋转运动角度定位方法。通过融合惯性测量单元中各惯性测量器件的实时测量数据,构建世界坐标系和载体坐标系的旋转矩阵,利用四元数分量求解C形臂旋转角度,从而对C形臂旋转运动进行定位。本文设计了精密电动旋转平台标定实验和C形臂旋转定位实验对本文方法进行了评估。结果在精密电动旋转平台标定实验中,本文设计方法的最大定位误差为0.5°;在C形臂的实验中,最大定位误差为0.8°,能够满足临床手术导航需求(定位误差不大于1°)。结论本文设计的定位方法不需要标定和校正过程,流程简单易行,具有很强的适应性,能够为后续手术导航提供必要的角度信息。

Objective Mobile X-ray imaging device（ C-arm） has become standard equipment in imageguide surgery due to its advantages of portability and real-time performance. However,most of these C-arm devices equipped in hospitals cannot implement rotation angle measurement. Methods In this paper,we design a rotational motion angle location method for C-arm device,based on the inertial measurement unit. Through fusing real-time inertial measurements from inertial measurement unit, rotational matrixes of the world coordinate system and carrier coordinate system can be derived. Then,the rotational angle of C-arm can be obtained utilizing of the quaternion component decompositions,which can be used to measure the rotational movement of C-arm. In order to verify the feasibility and the accuracy of the method,a calibration experiment of sophisticated electric rotating platform and a C-arm rotational positioning experiment are carried out. Results For the experiment of the electric rotating platform,the location error is less than 0. 5 degrees. For the experiment of C-arm, the maximum positioning error is less than 0. 8 degrees. These results meet the requirements of clinical surgical navigation（ location error less than 1 degree）. Conclusions This angle location method is simple, practicable and highly adaptable without requirements of calibration and correction positioning,providing necessary angle information for the subsequent surgical navigation.