Research On Optical Axis Alignment Technique Of Airborne Laser Communication

The premise of establishing a airborne laser communication link is the optical axis can be accomplished by the fast acquisition operation between two laser communication terminals.However,as the airborne platform is highly mobile,fast,and the trajectory is difficult to predict,the realization of airborne laser communication must be based on the acquisition,pointing,tracking(APT).The initial alignment as the first step in the acquisition,is the decisive factor for the success of the capture,the capture probability and the length of time.Therefor,in order to achieve high precision optical axis alignment of the coarse tracking system,the optical axis alignment must ensure the stability of the optical axis on the basis of the two sides of the communication position,attitude information to realize the real-time accurate analysis,so as to acquisition,pointing and tracking to provide protection.Firstly,this paper introduces the composition and working principle of airborne laser communication APT sub-system,and the influence factors of optical axis alignment error of airborne laser communication are analyzed.Also an initial alignment algorithm based on Global Positioning System(GPS)and Inertial Navigation System(INS)is proposed.By solving the real-time update data of GPS/INS integrated navigation system to get the alignment angle,the two-dimensional turntable rotation to achieve the optical axis alignment between two laser communication terminals is further controlled.And then this paper introduces the optical axis alignment system model of airborne laser communication in detail.Secondly,in view of the problems that the nonlinear vibration of the airborne platform and the relative motion of the communication terminal cause the large error of the optical axis stabilization,this paper designs a fuzzy neural network based PID control method to eliminate the vibration of the airborne platform to bring the optical axis stability error.And the composition and working principle of the fuzzy neural network PID control method are analyzed in detail.Finally,the simulation results show that the fuzzy neural network based PID control algorithm can eliminate the optical axis stability error caused by the platform vibration,and has the fast response speed and strong robustness.Through the establishment of the simulation experiment system,the performance of the initial alignment technology based on GPS/INS integrated navigation system in the process of optical axis alignment toairborne laser communication is studied.And then the alignment algorithm is verified from alignment accuracy.The experimental results show that the optical axis alignment system can meet the accuracy requirements of the optical axis of airborne laser communication and achieve the rapid and stable establishment of airborne laser communication link,also the correctness and stability of the optical axis alignment technology are verified by experiments.