Design And Implementation Of PAT Algorithm For Shipboard Laser Communication System

With the further development of China’s naval construction,the single radio communication method between ships has been unable to meet the requirements of high speed,security and reliability.The characteristics of space laser communication technology,such as concealment and immunity from electromagnetic wave interference,are very suitable as a powerful means of lineof-sight communication between ships in the future,and it is a strong guarantee for the development of sea-air-sky integrated communication networking in the future.In this paper,the pointing,acquisition and tracking(PAT)control algorithm of shipboard laser communication system is studied to assist laser communication devices to establish and maintain communication links effectively.First,the main control process of the PAT system is analyzed.According to the GPS/INS information of the two ships,the initial boresight pointing algorithm is designed to assist the optical antenna in initial position pointing.On the basis of pointing,appropriate scanning algorithms and beam capturing methods are determined for shipboard laser communication system application scenarios.Secondly,for the changing optical transmission relationship between the coarse tracking mechanism and the detector in the tracking process,the coupling effect between the axis system is analyzed,and the optical solution model is obtained by testing the correspondence between different conversion angles of the swing mirror and the moving orientation of the spot to improve the accuracy of the position solution of the spot error in the tracking process.In order to achieve high stability of the laser communication link,a linear active disturbance rejection coarse tracking algorithm is designed in this paper.The algorithm can effectively suppress the interference inside and outside the system,so that the light spot is always maintained in the detector field of view.This paper simulates the tracking performance of the tracking algorithm,analyzes the influence of different control parameters on the tracking speed and anti-disturbance performance,and realizes the optimal parameter adjustment of the tracking algorithm on this basis.Finally,the shipboard laser communication system platform is built,and the relative motion process between ships is simulated using a six-degree-of-freedom turntable to experimentally verify the execution accuracy and tracking performance of the scanning and tracking algorithm.The execution accuracy of the spiral rectangular scanning algorithm is ±5 arc-second under the condition of300 arc-second scanning step and 0.2s single point dwell time,which meets the scanning accuracy requirement.The linear active disturbance rejection coarse tracking algorithm designed in this paper reduces the peak tracking error by 44.24%and the standard deviation of the tracking error by 25.57% compared with the PID(Proportional Integral Derivative)control algorithm during the uniform linear tracking at 2°/s.Under the condition of the turntable’s sinusoidal disturbance with amplitude of 0.7° and frequency of 0.1Hz,the peak tracking error of the linear active disturbance rejection coarse tracking algorithm is reduced by 31.47% and the standard deviation of the tracking error is reduced by 9.59% compared with the PID control algorithm.The experimental results show that the linear active disturbance rejection coarse tracking algorithm can effectively improve the tracking performance and anti-interference capability of the shipboard laser communication system,which is more suitable for the complex and changing laser communication environment at sea.