针对同轴三反式空间光学遥感器对大口径主反射镜组件的高刚度、高强度、高热稳定性等特殊要求，提出一种基于Cartwheel型双轴柔铰的三点柔性支撑结构。首先利用无量纲方法研究了单个柔性支撑的柔度特性，然后利用有限元方法对反射镜组件的静力学、动力学与热特性进行灵敏度分析，确定了支撑结构中柔性环节的几何尺寸参数，并进行了有限元数值仿真。最后，利用面形值为λ/40均方根(RMS)的非球面镜进行了反射镜组件面形检测实验并利用等效球面镜组件进行了动力学实验。仿真与实验结果表明：当柔性环节尺寸为：壁厚t=8 mm，直梁高度h=4 mm，直梁长度L=8 mm时，在正交三向自重与15 ℃稳态温升作用下，反射镜面形精度RMS小于12 nm；反射镜组件一阶固有频率实验值为296 Hz，与仿真结果相差6%，能够满足使用要求。

The large aperture primary mirror assembly (PMA) mounted in space remote sensor should have the extraordinary virtues as high stiffness, high strength, high thermal stability etc.. A novel three-point flexural support configuration based on Cartwheel flexural hinge for large aperture PMA is presented in this paper. Firstly, the stiffness characteristic of the support structure is approached using the dimensionless design method. Then, static and dynamic analysis based on finite element method are performed on the PMA to find the optimal dimension parameters of the support flexure. Finally, optical test on a mirror with λ/40 root mean square (RMS) surface figure and vibration experiment on an equivalently spherical mirror are performed to validate the design configuration. The simulation and experiment results indicate that when the thickness of flexure t=8 mm, beam height h=4 mm, beam length L=8 mm, the surface figure of PMA can keep below RMS 12 nm under the load of 1 G gravity and 15 ℃ temperature change. The first natural frequency reaches 296 Hz, only deviating 6% from the analysis result. The Cartwheel flexure support can satisfy the extraordinary design requirements.