中文摘要：

目的颈椎的转动范围较大,传统的数字图像相关（digital image correlation,DIC）算法不能准确测量颈椎的活动度。提出一种改进的DIC算法,可以实现大转角的变形测量。方法采用一种子区窗口旋转的相关匹配法,通过引入子窗口的旋转角作为一个新的迭代量,和传统的位置参数（x,y）一起进行Newton-Rapshon迭代运算。在初始时只需提供位置和角度的迭代初值,即可求出精确的位移和角度值,同时通过平动和转动实验验证该方法的精度和可靠性。结果平动实验证实,本文方法与传统的DIC具有相同的效果,位移测量精度在0.5%以内;转动实验证实,本文方法可以测量任意转角的变形,角度误差与旋转量无关,角度误差在0.5°以内。将该方法用于颈椎的压缩实验,准确地测量了颈椎在压缩过程中的活动度。结论对比传统的DIC,子区窗口旋转的相关匹配法实现了颈椎在各种载荷作用下大范围活动度的测量,为颈椎的生理稳定和生理活动的测量判断提供了有效的方法。

英文摘要：

Objective To develop an improved DIC （digital image correlation） algorithm suitable for measuring large RQM （range of motion） of the cervical spine, as traditional DIC algorithm is not capable of accurately measuring ROM of the cervical spine due to its large rotation angles. Methods An algorithm which allowed rota tion of the subset window was proposed to achieve robust correlation matching in the measurement. A new itera tive variable, which represented the orientation of the subset, was introduced and incorporated in the NewtonRaphson iteration method together with the position variables （x,y）. By assigning an initial guess to these varia bles individually, the precise location and rotation angle could be determined in the deformed image. The preci sion of the proposed method was evaluated by translation and rotation experiments. Results The translation ex periment confirmed that the proposed method had the same accuracy as the traditional DIC, and the displace ment measurement accuracy was within 0.5%. While the rotation experiment indicated that the proposed method could measure the deformation at any angles with precision less than 0.5% The method was then applied to the measurement of ROM of cervical spine subjected to compressive loads and received qood results. ConclusionsCompared with the traditional DtC algorithm, the proposed method can achieve accurate measurement with large ROM for cervical spine tests with different loads, and provide an effective means for assessing the stability and physiological activities of cervical spine.