空间激光通信中捕获、瞄准和跟踪(Acquisition Pointing and Tracking,APT)系统采用复合轴结构，跟踪精度主要取决于精跟踪系统。为提高APT系统的稳健性和跟踪精度的角度，对APT精跟踪系统的控制算法进行了深入地研究，在系统的补偿设计中采用了稳健控制技术，建立了精跟踪系统的增广对象的数学模型，利用现代稳健控制理论中的γ综合法设计了稳健H∞控制器，使精跟踪系统带宽达到300 Hz以上，提高了粗精度带宽比。阶跃输入和等效正弦仿真表明，精跟踪系统具有很强的稳健性，跟踪精度优于0.8 μrad。室内模拟实验表明，精跟踪系统的室内跟踪精度达到4 μrad。

APT (Acquisition Pointing and Tracking) system of space laser communication adopts compound axis structure, its tracking precision rests with the fine tracking system. Make an intensive study on controlling algorithm of APT fine tracking system from the standpoint of increasing precision and robustness. The compensator of fine tracking system adopts robust control technology, constitutes the augmented process model of fine tracking system and designs the robust controller by γ synthesis method of modern robust control theory. It makes the system bandwidth be up to 300 Hz and increases the course-fine bandwidth ratio. The simulation by step input and equivalent sine shows that APT system has strong robustness and tracking precision of 0.8 μrad. By indoor analogy experiment, the tracking precision of fine tracking system can meet the requirement of 4 μrad.