状态观测器在航空相机中的应用

为了提高航空相机在摆扫方向上的成像分辨率,提出了一种基于状态观测器的加速度反馈控制方法,并对该方法的相位特性以及鲁棒性进行分析研究。首先,对镜筒角速度的测量元件光纤陀螺进行参数标定,采用频域法建立俯角控制系统的数学模型。其次,设计镜筒角加速度状态观测器,并提出了将状态观测器和牛顿预测器相结合的方法,解决了估计算法的相位滞后问题,进一步提高了估计角加速度的响应频带。最后,通过将观测到的角加速度信息构成加速度反馈控制系统,并且应用于某型长焦距倾斜CCD相机的俯角速度控制系统中。实验结果表明:基于状态观测器的加速度反馈控制方法能够显著地提高俯角控制系统的动态响应特性以及稳态精度。当俯角控制系统受到阶跃型的外界扰动时,镜筒的角速度出现了宽度为0.2 s的脉冲型波动,且幅值仅为采用超前-滞后控制方法的1/2。本文所述的控制方法具有较强的鲁棒性,适于工程应用。

Application of state observer in aerial camera

An acceleration feedback control method based on state observer is proposed to improve image resolution in pendulum swing direction of aerial camera.Phase characteristics and robustness of this method are analyzed.Firstly,the parameter of fiber optic gyro which is used to measure angular velocity of tube is calibrated.Frequency domain analysis method is used to establish the mathematical model of depression angle control system.Then,a state observer is incorporated into Newton predictor of tube angular acceleration is designed in order to solve the problem of phase lag and further improve the response band of estimated angular acceleration.Finally,the acceleration feedback control is applied to depression angle control system of long-focus sloping aerial camera.Experiment results indicate that the acceleration feedback control based on state observer can improve the dynamic performance and steady state accuracy of depression angle control system.For the step external disturbance,the angular velocity of tube only shows a pulse fluctuation with a width of 0.2 s,and the amplitude is one half of that of lag-lead compensation method.The method is effective,robust and is very suitable for engineering.