卫星光通信APT控制系统H_∞设计

H_∞ Control Applied for APT System of Inter-satellite Laser Communications

捕获瞄准跟踪(APT)控制系统的设计是影响整个星间光通信系统性能的重要因素。利用指向偏差的概率分布阐述了卫星光通信过程中捕获概率、跟踪误差及误码率受卫星平台振动和终端装置参数摄动的影响,通过功率谱分析了卫星平台振动在低频段、对象不确定性在高频段对指向偏差的影响,并对其进行了模型化分析。采用H∞控制混合灵敏度设计方法同时抑制干扰和处理受控对象不确定性问题进行控制器设计。仿真验证表明该方法得到的控制器对平台干扰具有抑制力,对对象摄动具有鲁棒性。

The design of an acquisition,pointing and tracking（APT） control system is a critical factor for the overall inter-satellite laser communication performance. The probability density function of the APT system point error is first deduced,and then according to this function,the acquisition probability,tracking error and bit error probability are introduced in detail,which are affected by satellite platform vibration and antenna parameter perturbation in the process of inter-satellit laser communication. The impact on point error caused by satellite platform vibration in low frequency domain and uncertainty of plant in high frequency domain is analyzed by the stationary random signal power spectrum. Based on the power spectrum properties,H∞ mixed sensitivity control method is applied to APT control system design to eliminate the impact of vibration and uncertainty. Simulation proved that the controller designed by the H∞ control method resists vibration effectively,and possesses robustness when bounded uncertainty of plant emerges.