目的 研究使用四元数法评价医用机器人的定位准确度，为建立医用机器人专用标准提供信息。方法 选取图像引导式手术机器人产品，在机器人坐标系和工具坐标系下分别测量同一组空间靶点（共40个）的位置，使用四元数法进行坐标系转换，计算定位误差，分析影响定位误差的因素。结果 四元数模型的比例因子和空间靶点数量对结果有重要影响。比例因子不能简单默认为1，应根据实际测量值进行计算|各个靶点定位误差的方差与空间靶点数量呈反比。结论 四元数法作为一种解析方法，有助于评价医用机器人定位准确度，未来标准中应明确比例因子、靶点数量等参数的设置。

Objective To study how to use quaternions to evaluate positioning accuracy of medical robots and provide information for future development of standards. Methods The image-guided surgical robot products were selected to measure the positions of the same group of spatial targets (40 in total) in the robot coordinate system and the tool coordinate system. The quaternion method was used to transform the coordinate system, calculated the positioning error, and analyzed the factors that affect the positioning error. Results The results were affected by the scale factor of the quaternion model and the number of spatial targets. The scale factor could not be simply defaulted to 1, and should be calculated based on the actual measured value. The variance of each target positioning error was inversely proportional to the number of spatial targets. Conclusion In the future, the standard should clarify the setting of parameters such as the scale factor and the number of targets.