利用动态靶标谐波特性评价光电经纬仪的跟踪性能

提出了一种利用动态靶标实现光电经纬仪跟踪性能等效正弦评价的新方法。分析了动态靶标目标及相应跟踪误差的幅度谱和功率谱特性,提出将动态靶标看作由有限项基频谐波和整数倍基频高次谐波的加权和组成的谐波源。根据被检光电经纬仪跟踪性能设计等效正弦信号,利用动态靶标产生与等效正弦信号同频率的谐波信号完成光电经纬仪跟踪误差系统在该频率下幅频特性函数值的测试。等效正弦的幅值和测得的幅频特性值乘积即为跟踪等效正弦信号的跟踪误差最大值,从而实现了跟踪性能评价。利用该方法测得方位方向的最大跟踪误差为0.65′,远小于4′的指标要求,而利用动态靶标直接检测的值为4.7′。实验表明该方法准确、可行,同时避免了直接利用动态靶标检测时可能使跟踪伺服系统出现过度校正的问题。

Evaluation of tracking performance of photoelectric theodolite by using harmonic property of dynamic target

A novel approach based on the equivalent sine testing is proposed to evaluate the tracking performance of a photoelectric theodolite by using a dynamic target. The characteristics of the amplitude and power spectra of the dynamic target and the relative tracking errors are analyzed,and the dynamic target is taken as a harmonic source formed by the finite weighted sums of the base frequency harmonics and the weight sums of high harmonics that is the integral times of base frequency. The angular frequency and amplitude of an equivalent sine signal are designed according to the testing desire, and the amplitude-frequency characteristic function value of tracking error system is tested by using the harmonic signal in the same angular frequency with the equivalent sine signal generated by the dynamic target. The amplitude of equivalent sine and the function value are multiplied to get the maximum tracking error of tracking signal, and then the tracking performance is evaluated by using the proposed method. The tracking performance of a photoelectric theodolite is evaluated by this method. Compared with the maximum tracking error of 4.7' measured by the dynamic target directly, the proposed method can offer the maximum azimuth tracking error of 0.65', which is far less than the desired maximum tracking error of 4'. The result shows that the method can evaluate the tracking performance of the theodolite exactly and can avoid the possible excessive correction of tracking servo system by using dynamic target directly.