旋转机械升降速信号的瞬时频率估计

旋转机械的升降速过程是一种非平稳过程，对其测试信号进行分析需要用时频分析方法，如短时傅里叶变换(STFT)及小波变换等方法。对于多分量信号，峰值搜索法经常被用来获取旋转机械在升降速过程中瞬时频率随时间变化的规律。但是，由于噪声和信号中邻近成分间的干扰，直接寻找的结果不能保证其精度和准确性。采用隐马尔可夫模型(Hidden markov models，HMM)进行去噪处理，极大地降低了噪声和干扰对峰值搜索结果的影响，明显提高了结果的精度。仿真试验表明该方法可以取得好的结果。

INSTANTANEOUS FREQUENCY ESTIMATION OF RUN-UP OR RUN-DOWN SIGN OF ROTATING MACHINERY

Stages of run-up or run-down of rotating machinery are non-stationary. Then, the methods of time-frequency analysis, such as short-time Fourier transform,wavelet transform and so on, will be employed to analyze the corresponding test signals. To obtain the laws of the instantaneous frequency of multi-components signals during the run-up or run-down periods, the method based on peak search is widely used. However, the results through direct searching are often worse in precision, due to the interference of strong noise and adjacent components of signal. The hidden markov models are applied to solve the problem. Simulation indicated a better result could be obtained by the method based on HMM.