提出了基于离散误差不变量的移动副误差运动评价方法。该方法不依赖于功能点与测量坐标系的选取，反映了误差运动的整体性质。通过6D高精度传感器获得运动刚体的6自由度误差参数。研究运动刚体上点、直线等几何特征的离散轨迹，并与理想曲线和曲面进行对比，建立了刚体上任意点的准线轨迹、任意方向的球面像曲线轨迹的误差评价模型。提取空间准线误差密度和球面方向误差密度两项为运动整体不变量，最小准线误差和最小球面像误差两项为运动特征不变量，以此作为误差运动的评价指标。开展了仪器不同安装位置的对比验证试验，结果表明，整体不变量与特征不变量评价指标是离散运动的固有性质，能更为准确客观地评价移动副的误差运动。
A novel evaluation approach based on invariants is proposed to deal with the discrete error motion of the prismatic pair. The approach reflects the global property of the discrete error motion, which does not depend on the measurement coordinate system. The new 6D high-precision measurement instrument is used to investigate the six error terms. The evaluation model for directrix and spherical image curve is set up to study the geometry property of the moving body compared with the ideal one. The density of directrix error space and spherical envelope circle error surface are selected as the global evaluation indicators, while the minimal directrix error and the minimal spherical image curve error as the characteristic indicators. Three contrast tests are presented to illustrate the consistency and objectivity of the invariant indicators, which can evaluate the accuracy of the prismatic pair comprehensively and objectively.
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