基于边沿捕捉与中值滤波的航空发动机转速测量

Aero Engine Rotate Speed Measurement Based on Edge Capture and Median Filtering

论述了利用边沿捕捉不间断检测旋转机械转速的一般方法。在这个基础上,介绍了一种航空发动机数字转速表设计。该转速表用迟滞比较和光电隔离电路对传感器信号进行调理;用ARM核单片机的一个32位高速定时/计数器捕捉通道连续测量每一个转速脉冲的周期,得到相对转速更新率冗余的瞬时转速测量;再用中值滤波器对最新转速更新周期内所采集的冗余转速数据进行更新前数字滤波,得到等速率的转速更新输出,同时降低尖峰型噪声干扰;用另一个定时/计数器的计数功能避免了对零或接近零的低转速数字测量问题。

An edge capture based general method for speed measurement of rotate mechanic was described. Based on this method, a digital tachometer design for aero engine was introduced. In the proposed tachometer design, hysteretie comparator and optic-isolation circuit was adopted for sensor signal conditioning. Capture function of an ARM core single-chip microcontroller＇s 32 bit high speed timer/counter channel was utilized to measure the period of every speed pulse and get redundant rotate speed measurement data respected to update rate. The redundant speed data within the nearest update period were filtered with median filter before speed update to form constant rate speed update output and suppress spike noises. Counter function of another timer/counter was used to avoid the problem existed with digital measurement to zero or near zero low rotate speed.