用于海洋环境无线激光通信的倾斜镜系统建模及控制方法研究

发布时间：2018-11-15 15:36

【摘要】：无线激光通信技术以其高速、便捷等独特的优势,在海洋领域有着广阔的应用前景。然而,激光束在海面传输过程中易受到大气湍流的影响,在通信接收端产生光束偏移、到达角起伏等现象,严重影响激光通信的质量。倾斜镜系统被用于无线激光通信中,用于实时校正光束偏移,使得激光束能实时稳定的与接收端对准。然而,由于受到倾斜镜执行器材料的滞回特性、执行器动态响应、执行器间相互耦合等因素的限制,传统的控制器难以对倾斜镜进行精确和高速的控制,降低了倾斜镜系统的校正效果。本文设计并搭建了一套闭环倾斜镜系统,并对倾斜镜的滞回特性,动态响应特性和耦合特性进行了测试。采用前馈控制的方法对倾斜镜滞回效应进行了补偿。根据倾斜镜结构推导了系统的物理模型,为后续数值建模提供有效参考。采用子空间辨识的方法,基于倾斜镜系统输入输出数据,建立开环倾斜镜系统的动态耦合数学模型,并通过测试实验评估了模型的准确性和建模方法的可行性。基于动态耦合模型进行了 H_2最优控制器设计及闭环实验,以提高闭环系统的性能,并与传统的基于静态模型的控制器进行对比,观察比较两种控制器的闭环控制效果。实验结果显示,经滞回补偿后倾斜镜的最大滞回量由11.29%降低到1.4%。倾斜镜系统动态耦合模型的VAF(Variance accounted for)值达到97%,相比之下,传统的静态模型VAF值为65%,模型的准确性大大提高。基于动态耦合模型的H_2控制器使系统的闭环带宽达到219Hz,而传统的基于静态模型的控制器带宽为100Hz左右,控制器性能显著提高。本文提出了将子空间辨识和H_2最优控制用于倾斜镜系统控制的思路,验证了滞回补偿、系统建模、控制器设计方法的可行性,研究成果可用于海洋环境无线激光通信中的闭环倾斜镜系统,提高系统对于光束偏移矫正的性能,进一步提高通信质量。
[Abstract]:Wireless laser communication technology has a broad application prospect in ocean field because of its unique advantages such as high speed and convenience. However, the laser beam is easy to be affected by atmospheric turbulence in the process of sea surface propagation, which results in beam deviation and angle of arrival fluctuation at the receiving end of the communication, which seriously affects the quality of laser communication. The tilting mirror system is used in wireless laser communication to correct the beam offset in real time so that the laser beam can be aligned with the receiver in real time. However, due to the hysteretic characteristics of the tilting mirror actuator, the dynamic response of the actuator and the coupling between the actuators, it is difficult for the traditional controller to control the tilting mirror accurately and at high speed. The correction effect of tilting mirror system is reduced. In this paper, a closed loop tilting mirror system is designed and built, and the hysteretic, dynamic response and coupling characteristics of the tilting mirror are tested. The hysteretic effect of tilting mirror is compensated by feedforward control. The physical model of the system is derived according to the tilting mirror structure, which provides an effective reference for the subsequent numerical modeling. Based on the input and output data of tilting mirror system, the dynamic coupling mathematical model of open loop tilting mirror system is established by using subspace identification method. The accuracy of the model and the feasibility of the modeling method are evaluated by testing experiments. Based on the dynamic coupling model, the optimal controller design and closed-loop experiment are carried out to improve the performance of the closed-loop system. Compared with the traditional controller based on static model, the closed-loop control effect of the two controllers is observed and compared. The experimental results show that the maximum hysteresis of the tilting mirror is reduced from 11.29% to 1.4% after hysteresis compensation. The VAF (Variance accounted for) value of the dynamic coupling model of tilting mirror system is 97. Compared with the traditional static model, the VAF value is 65 and the accuracy of the model is greatly improved. The controller based on dynamic coupling model makes the closed-loop bandwidth of the system reach 219Hz, while the traditional controller based on static model has a bandwidth of about 100Hz, so the controller performance is improved significantly. In this paper, the idea of applying subspace identification and HStat2 optimal control to tilting mirror system control is proposed. The feasibility of hysteretic compensation, system modeling and controller design is verified. The research results can be applied to the closed loop tilt-mirror system in wireless laser communication in marine environment, which can improve the performance of the system for beam offset correction and further improve the communication quality.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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