莫尔条纹光电信号的非线性跟踪微分测速方法

Method of velocity measurement based on Moiré fringe and nonlinear tracking differentiator

为了实现在低速情况下系统速度的检测,提出了一种基于莫尔条纹光电信号和非线性跟踪微分器的测量角速度和角加速度的方法。首先,分析了莫尔条纹光电信号特性;然后结合非线性跟踪微分器理论,对编码器输出的光电信号进行滤波和相位补偿;最后,将两级非线性跟踪微分器级联,同时得到速度和加速度。实验结果表明:该方法增加了低速时采样频率,提高了速度测量的平稳性、精度和实时性。将该方法应用于某采用21位编码器作为角度传感器的系统中,成功实现了速度及加速度地检测。当速度降低到0.0017(°)/s时,设置采样时间为5ms,则采样频率为通常方法的20倍,更好的解决了低速系统对测速平稳性、精度和实时性的要求。

In order to realize velocity and acceleration measurement at low speed, a new type method of velocity measurement at low speed was designed which is based on the method of Moire fringe and nonlinear tracking differentiator. First of all, the electric signal of Moire fringe was analyzed. Then the electric signal from photoelectric encoder was filtered by nonlinear tracking differentiator and the phase delays were compensated. Finally, velocity and acceleration measurement was realized by using cascaded nonlinear tracking differentiators. The test proves that the stationarity and precision of velocity measurement at low speed are improved, as well as the sampling frequency. The method was applied in a system with a 21-bit encoder as the angle sensor, and velocity and acceleration could be measured. When the speed is 0.001 7（°）/s and sampling time is 5 ms, sampling numbers is 20 times than that of ordinary methods. The real-time performance, stationarity and precision of velocity measurement at low speed can be improved by using the method.