光电搜跟系统关键问题的研究

The electro-optical search and track system can isolate the detector's line of sight (LOS) from the disturbances and vibrations of the vehicle to achieve accurate pointing, and it is widely used in inertial navigation systems,reconnaissance systems and weapon systems.The project focuses on the research of multiaxis kinematic coupling, nonlinear friction compensation and compensation of the tracker time-delay of eelectro-optical search and track system on a mobil carrier, which are the main factors affecting the performance of the system.According to the multiaxis kinematic coupling problem caused by the changing gimbal moment of inertia with the change of frame positon,a novel composite controller combine a feedback part with a feed-forward compensation part based on a disturbance observer(DOB) is presented. According to the chattering and creeping phenomenon caused by nonlinear friction because of the changing relative position of the movement carrier and the detector, a compound controller also based on a DOB is introduced. First, an approximate friction model is obtained based on the analysis of the influence factors of the system friction. Then, a friction compensation scheme based on the approximate friction model is in introduced. Finally, a DOB is introduced to estimate both states and disturbances by simple computations, and the estimated value can be employed in the feed-forward compensation design to improve the performance of the system.A novel idea of the proposed strategies lies in that they take coupling effects as internal disturbance, and the DOB is introduced to estimate the lumped disturbance which include external disturbances, such as vehicle disturbance torque and mass unbalanced torque, and internal disturbances, such as model mismatches and coupling effects. To compensate the tracker's delay effect,a two-stage Kalman estimator for tracking maneuvering and non-maneuvering targets is provided, which can improve system stability, dynamic performance and tracking accuracy. Finally, Simulation and experimental will be carried out to to verify the effectiveness of the proposed method which can provide theoretical proof and experience basis for developing high-acuracy electro-optical search and track system.

光电搜跟系统能隔离载体扰动。保持探测器视线稳定，广泛应用于惯性导航、军事侦察系统中。课题对光电搜跟系统中存在的轴系耦合、非线性摩擦等未知扰动及跟踪时延分别展开研究。将影响系统性能的各通道之间的状态耦合看成是各个通道的扰动，设计相应的观测器或估计器；针对频繁换向时由于摩擦造成的低速抖振和爬行现象，通过系统分析摩擦的影响因素，得出近似的摩擦模型，在基于该摩擦模型补偿的基础上，利用前述扰动观测器观测出摩擦的过补偿或欠补偿、系统建模误差带来的不确定性和其他未知的外界扰动，并用此观测值进行前馈补偿，形成基于反馈控制和扰动观测前馈补偿的复合控制方案，以减小系统耦合、非线性摩擦和未知扰动对系统性能的影响；针对图像跟踪器的统计特性不确定性噪声及滞后的影响，提出了一种基于两级Kalman的滤波预测补偿方法，用于改善光电搜跟系统的动态品质。最后，通过理论研究和实验验证，为研制高精度光电搜跟系统提供理论依据。

光电搜跟系统被广泛应用于军事航空领域和消防、环境监控等民用领域,本项目对光电搜跟系统中存在的轴系耦合、非线性摩擦等未知扰动及跟踪时延分别展开研究。将影响系统性能的各通道之间的状态耦合看成是各个通道的扰动，设计相应的观测器或估计器。针对频繁换向时由于摩擦造成的低速抖振和爬行现象，通过系统分析摩擦的影响因素，得出近似的摩擦模型，在基于该摩擦模型补偿的基础上，利用前述扰动观测器观测出摩擦的过补偿或欠补偿、系统建模误差带来的不确定性和其他未知的外界扰动，并用此观测值进行前馈补偿，形成基于反馈控制和扰动观测前馈补偿的复合控制方案，以减小系统耦合、非线性摩擦和未知扰动对系统性能的影响。为解决现有终端滑模控制算法在收敛速度和抖振方面的问题，提出一种连续非奇异快速终端滑模控制方法，采用变系数双幂次趋近率和非奇异快速终端滑模面相结合的设计方式，提高系统状态在趋近和滑动阶段的收敛速度，通过Lyapunov 稳定性方法证明所提出的控制率可使得状态轨迹在扰动存在的情况下，在有限时间内快速收敛到一个区域。与传统方法相比，所提出的控制率是连续的，因此抑制了抖振，拥有更高的控制精度，仿真结果验证了算法的有效性。为解决光电搜跟系统中由于光电跟踪器时滞降低系统跟踪精度的问题，借鉴机动目标跟踪的思想，提出一种改进的“当前”统计模型自适应滤波算法，对滞后的脱靶量信号进行补偿。通过自适应的调整机动频率和加速度方差，提前预测目标的状态信息，从而达到补偿时滞的目的。仿真验证了该算法的有效性，并进一步在某光电跟踪设备上比较了有无时滞补偿的速度跟踪曲线，结果表明所提算法有效提高了目标跟踪精度，对跟踪器时滞起到了很好的补偿效果。所提出的几种控制算法一方面进行了仿真分析，同时也在试验平台上进行了实验论证，具有很高的推广价值和工程应用前景。