研究了基于补偿式柔性平行四杆机构的高精度位移平台的运动精度，对变形板尺寸误差、比例杆球心距误差和内外变形板装配夹角误差等误差源进行了分析计算。采用半梁模型分析了变形板，得到变形板行程与耦合位移量的关系，给出了平台直线度误差和耦合位移量误差关于平台位移和变形板尺寸的表达式。使用自准直仪和高精度微分测量头对平台直线度和耦合位移量进行了测量，结果表明：该补偿式结构的高精度无导轨位移平台在大行程(5 mm)工作时，仍具有较高的运动精度，直线度小于1.5″，耦合位移量小于13.7 μm，与理论分析吻合。

The motion accuracy of a platform based on two compensated flexible four-bar linkages was researched and three error sources,namely, batten size error, the sphere center distance error of ratio lever and the assembling angle between the inner and external battens were analyzed. A semi-beam model was established to analyze the deformation of the batten and the relationship between working displacement and coupled displacement. The expressions of the platform straightness error and the limiting coupled displacement error which was concerned with the platform displacement and the batten sizes were derived. Finally,an autocollimator and a high precise measuring head were used in the measurements of the platform straightness and the coupled displacement. The experimental results show that the straightness error is smaller than 1.5″ and the coupled displacement error is less than 13.7 μm when the stroke of the displacement platform is no longer than 5 mm. It is proved that the platform works with high motion accuracy and the experimental result is consistent with the analysis results.