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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。
In order to improve the imaging resolution of aerial camera in the sweep direction, a state observer-based acceleration feedback control method is proposed. The phase characteristics and robustness of the method are analyzed. Firstly, the parameters of optical fiber gyroscope are calibrated, and the mathematical model of depression angle control system is established by frequency domain method. Secondly, the lens angular acceleration state observer is designed. The method combining the state observer and Newton predictor is proposed to solve the phase lag problem of the estimation algorithm and further improve the response frequency band of the estimated angular acceleration. Finally, the observed angular acceleration information forms an acceleration feedback control system and is applied to the depression speed control system of a long focal length tilt CCD camera. The experimental results show that the state observer-based acceleration feedback control method can significantly improve the dynamic response characteristics and steady-state accuracy of the depression angle control system. When the depression angle control system is disturbed by the step-type external disturbance, the angular velocity of the lens tube appears pulse-like fluctuation of width 0.2s, and its amplitude is only 1/2 that of the advanced-hysteresis control method. The control method described in this paper has strong robustness and is suitable for engineering application.