激光多普勒测速系统可实现空中运动平台的速度测量，平台的姿态测量误差是影响其测速精度的重要因素。为实现运动平台三维速度的测量，以相干探测原理为基础，设计并搭建了全光纤三光束激光多普勒测速系统，建立了运动平台三维速度测量的数学物理模型，对系统测速相对误差进行了数值模拟研究。研究结果表明，姿态测量误差对测速精度的影响不可忽略；随着俯仰角度的不同，俯仰误差与旋转误差对测速精度的影响程度会发生变化；测速精度与旋转误差呈线性关系，而与俯仰误差存在着非线性关系。研究结果可为激光多普勒测速系统的设计以及速度修正提供理论依据。

The velocity of aerobat can be measured by laser Doppler velocimetry system and its accuracy is seriously affected by the attitude measurement errors. To precicely measure the three-dimensional (3D) velocity, an all-fiber triple-beam laser doppler velocimetry (TLDV) system based on coherent detection principle is proposed. Mathematical model of velocity measurement is described. According to the simulations, it is found that, firstly, effect of the attitude errors on the velocity measurement accuracy should not be neglected; secondly, with the pitch angle changing, influence of the pitch error and roll error on velocity measurement accuracy change; thirdly, the relationship between velocity accuracy and roll error is linear, while that between the accuracy and pitch error is nonlinear. The conclusions can be used for the design and velocity error correction of laser Doppler velocimetry system.