基于双液晶偏振光栅的机载光电跟瞄平台技术研究

Research on Technology of Airborne Optoelectronic Tracking Platform Based on Dual Liquid Crystal Polarization Grating

为实现新型机载光电跟踪平台轻量化、小型化与高精度化设计,提出一种应用于机载平台下的基于双液晶偏振光栅光束偏转机构的光电跟瞄方法。建立了基于视轴解耦的双液晶偏振光栅光束跟瞄反向公式模型,该模型只需输入跟踪点方位与俯仰角度坐标即可计算出两共轴光栅旋转位置,通过两共轴光栅的旋转来进行光束偏转;相比传统双棱镜光束偏转模型反向公式,该模型具有模型简单、运算快速、精度较高等优点;将基于视轴解耦的双液晶偏振光栅光束偏转反向公式模型与线性二次型调节器控制算法相结合嵌入控制板以实现跟踪功能。通过试验检测了系统跟踪性能结果表明:该双液晶偏振光栅跟踪模型在载体扰动的情况下可以实现目标跟瞄,在动态跟瞄实验中,采用视轴解耦与线性二次型调节器相结合的控制策略使得系统跟瞄精度得到明显提升,相比比例积分微分控制器系统方位与俯仰轴实时跟踪残差峰峰值均下降40%以上,在2°@0.5 Hz与5°@0.2 Hz载体扰动情况下双轴脱靶量均方根值综合统计数值分别达到328μrad与289μrad,验证了所提跟瞄模型的有效性。

With the continuous progress of optoelectronic tracking technology,optoelectronic tracking systems,as core components in engineering fields such as laser communication,laser guidance,and space observation,are increasingly widely used in optoelectronic platforms.However,in some special cases,the application of traditional optoelectronic tracking equipment is greatly limited due to factors such as narrow installation space,limited platform load,and higher requirements for tracking accuracy and response speed.The dual grating optoelectronic tracking device is a new type of beam deflection device that rotates two coaxial gratings for beam deflection.This device has the advantages of small rotational inertia,small volume,and high tracking accuracy,and has broad application prospects in fields such as laser communication,laser guidance,and LiDAR.In order to overcome the shortcomings of traditional airborne optoelectronic tracking devices such as large volume and weight,and achieve lightweight of the new airborne optoelectronic tracking platform.A miniaturization and high-precision design has been proposed for an optoelectronic tracking method based on a dual grating beam deflection mechanism applied to airborne platforms.This article establishes a dual grating optoelectronic tracking and aiming platform control system based on Linear Quadratic Regulator(LQR)optimal control,selects two independent rotating liquid crystal polarization gratings placed in parallel along the same axis as the beam deflection actuator,and establishes a beam deflection reverse formula based on line of sight decoupling for target tracking.The three meter collimator is used to simulate the long-distance target,the double grating photoelectric tracking and aiming system is placed on the six degrees of freedom swing table,and the azimuth axis and elevation axis disturbances are applied.The 1053 nm laser is emitted into the double grating photoelectric tracking and aiming system through the ten meter collimator,and the tracking accuracy is tested.The dual grating optoelectronic tracking and aiming system has successfully completed tracking experiments based on platform disturbances of different frequencies and amplitudes.Through experimental data analysis,it is found that the tracking accuracy of the airborne optoelectronic tracking and aiming system based on the dual grating meets the system design indicators,with a tracking residual RMS(Root mean square)statistical value less than 350μrad.Compared with the PID tracking algorithm,the peak to peak values of real-time miss distance data for azimuth and elevation have decreased by more than 25%.After adding LQR and Axis of Sight Decoupling Algorithm,the RMS statistical values of the biaxial miss distance under 2°@0.5 Hz and 5°@0.2 Hz disturbances are 328μrad and 289μrad,respectively,ensuring the reliability of subsequent experiments based on the dual grating optoelectronic tracking system A dual grating optoelectronic tracking and aiming system based on LQR optimal control and line of sight decoupling has been designed,which has advantages such as high tracking accuracy,small moment of inertia,small weight,and small volume.The effective aperture of the liquid crystal polarization grating in the system is 50 mm,and the RMSstatistics of the off axis reflection system wave aberration are less thanλ/12.Select the incident light band asλ=1053 mm,after coating the optical antenna with a thickness of 1053 mm,the reflectivity of the 1053 nm laser beam is greater than 99.95%.The maximum beam diffraction deflection angle of the dual grating system is±15°.After experimental testing,it was found that the dual grating optoelectronic tracking and aiming system has achieved tracking of simulated long-distance targets,and the system′s azimuth and elevation tracking accuracy has been greatly improved,achieving the design target of a biaxial miss distance RMS less than 350 urad.The correctness and effectiveness of the combination of LQR control theory and line of sight decoupling algorithm have been verified,providing experimental reference and theoretical support for the development of new optoelectronic tracking technology based on dual gratings.