为了准确识别空间滤波转速遥测中的被测体旋转方向, 提出了一种基于功率谱密度分析的旋转方向辨识方法.该辨识方法是将占空比为0.5的两个光电池线阵列错位半个栅距而形成一个差分空间滤波器, 用两个差分空间滤波器相距一定距离平行排列构成一个双差分空间滤波传感器; 根据差分空间滤波信号的功率谱密度互为共轭的特性, 用双差分空间滤波传感器输出的四路信号计算出两个线速度方向系数D1和D2, D1和D2的符号代表了两个差分空间滤波器处的线速度方向; 用D1和D2的符号、两个差分空间滤波信号的中心频率f1和f2的相对大小, 来判别被测体图像的旋转方向及中心.D1>0、D2<0代表顺时针旋转, D1<0、D2>0代表逆时针旋转; D1D2>0时, 旋转方向由f1、f2的相对大小和D1的符号确定.该方法能有效辨识空间滤波转速遥测中的旋转方向, 具有简单、适应性强和应用方便的特点.

In order to exactly identify the rotational direction of the measured body in the remote angular-velocity measurement with spatial filtering technique, an approach to estimating the rotational direction was proposed based on the analysis of power spectrum density. In the identification method of rotational direction, two identical photovoltaic-cell arrays with the duty ratio of 0.5 are arranged each other with the shift of a half spatial period, which leads to a differential spatial filter. Two parallel differential spatial filters are placed in a certain interval, and then construct a sensor with double differential spatial filters. The power spectrum densities of the two output signals from one differential spatial filter are conjugated each other, thus the direction coefficients D1 and D2 of the linear velocities on two differential spatial filters are calculated with four output signals of the sensor, and the signs of D1 and D2 represent the moving directions of the measured-body image on the differential spatial filters. The rotational direction and center of the measured-body image can be determined by the signs of D1 and D2, together with the relation between the central frequencies f1 and f2 of two output signals from the differential spatial filters. D1>0 and D2<0 represent the clockwise rotation, and D1<0 and D2>0 represent the counter-clockwise one. For other cases as D1D2>0, the rotational directions can be decided by the sign of D1 and the relative relation between f1 and f2. The proposed method can effectively identify the rotational direction in the remote angular-velocity measurement with spatial filtering technique, which has the features as being single and easy to operate, and having strong adaptability.