线性扩张状态观测器的改进及在空间光通信粗跟踪的应用

针对传统自抗扰控制器的扰动补偿效果随着扰动频率增加迅速下降的问题,提出了一种基于改进的线性扩张状态观测器的自抗扰控制方法。该方法首先对粗跟踪进行系统分析、简化及辨识;然后对线性扩张状态观测器的观测原理进行详细推导与论证,从理论上指出其不足,提出了一种改进的线性扩张状态观测器;最后将改进的算法与PID调节器相结合,实现了粗跟踪的自抗扰控制。实验结果表明:针对幅度在1、频率在0.5~2.5 Hz间的外部位置扰动,传统的自抗扰控制器随着扰动频率的增加,扰动隔离度下降非常明显,2 Hz时的提升程度仅为0.5 Hz处的9.5%;而采用改进的算法使扰动隔离度至少提高了4.146 dB,且随着扰动频率的增加,扰动隔离度的提升非常稳定,2.5 Hz时的提升程度与0.5 Hz处几乎一致;此外,该方法有较好的鲁棒性,允许被控对象在20%的范围内变化。理论分析、仿真分析、物理实验均证明该方法的有效性,对类似的光电跟踪系统有一定的参考价值。

Improvement of linear ESO and its application in space optical communication coarse tracking

In order to address the problem that disturbance compensation effect of traditional active disturbance rejection controller(ADRC) decreased rapidly with the increase of disturbance frequency, a new ADRC method based on modified linear extended state observer(ESO) was proposed in this paper. Firstly, the coarse tracking system was analyzed, simplified and identified, and then the disturbance observation theory of ESO was derived and demonstrated, and its disadvantages were pointed out theoretically. According to that, an improved linear ESO was proposed and its advantages were illustrated by theory and simulations. Finally, the ADRC of coarse tracking system was realized with the improved linear ESO and PID adjuster. The experimental results show that as for the external position disturbance with the magnitude of 1 and frequency of 0.5-2.5 Hz, the disturbance isolation degree declines significantly with the increase of disturbance frequency adopting the traditional ADRC. While the disturbance isolation degree improves at least 4.416 dB adopting the improved ADRC in this paper, and the disturbance isolation degree increases stably with the increase of disturbance frequency, which is almost the same at 2.5 Hz and 0.5 Hz. What's more, the proposed method is robust and the change within 20% of the controlled object is allowed. In conclusion, theoretical analysis, simulation analysis and the physics experiment prove this method is effective, and it has some reference value for similar photoelectric tracking system.