为改善航空光电载荷用音圈致动快速反射镜的控制性能，提出一种降阶自抗扰控制方法。首先，对快速反射镜(Fast Steering Mirror，FSM)模型进行了分析并获取了模型参数。根据自抗扰 控制理论，设计了FSM的三阶通用自抗扰控制器。将电涡流传感器的测量结果视为已知，提出降阶扩张状态观测器及其对应的自抗扰控制器设计方法。根据控制器带宽设计思想，推导了对于FSM 这 类二阶欠阻尼对象的控制律，并给出了加入扰动补偿量的控制律的具体实现形式。实验结果表明，降阶自抗扰控制能明显改善FSM的位置阶跃响应动态性能，能实现无超调与振荡的阶跃响应，稳态 时间由11.7 ms提升至9.2 ms，同时能够降低FSM对位置斜坡输入跟踪的稳态误差，并改善其速度响应动态过程，像移补偿稳速时间由10.2 ms提升至7.8 ms，提升约24%。降阶自抗扰控制具有实现简 单、运算量小的特点，能够明显提升FSM的动态性能。

A reduced-order autodisturbance rejection control method was proposed to improve the control performance of a fast steering mirror(FSM) driven by VCA applied in aerial photoelectric loads. The FSM model was analyzed, and the model parameters were obtained. Based on the theory of active disturbance rejection control (ADRC), the general third-order ADRC of the FSM was designed. The eddy current sensor measurement results were assumed, and the reduced-order extended state observer and its corresponding ADRC design method were proposed. Based on the controller bandwidth design theory, the control law of the second-order under damped object, such as FSM, was deduced, and the specific realization form of the control law with the disturbance compensation value was provided. The experimental results show that the reduced-order ADRC can significantly improve the dynamic performance of the positional step response of the FSM and can achieve a step response without overshoot and oscillation. The steady-state time reduces from 11.7 to 9.2 ms.In addition, the tracking steady-state error of the position ramp response declines, and the dynamic process of speed response improved. The speed stabilization time of image motion compensation drops from 10.2 to 7.8 ms, which is approximately 24%. The reduced-order ADRC can significantly improve the dynamic performance of FSM because of its simpler implementation and less computation.