振动信号频率跟踪的反馈修正自适应陷波器法

采用自适应陷波器跟踪振动信号频率时，存在持续跟踪精度不高的问题。通过分析指出持续跟踪精度不高的根本原因是ANF误差收敛至局部最优值，借鉴反馈控制思想，提出一种反馈修正ANF。根据ANF输入输出信号的相关性，设计频率跟踪精度评估因子，实时监控ANF频率跟踪精度。若评估因子小于给定阈值，则认为ANF丢失振动信号频率，通过反馈调整ANF参数而非重新初始化来适当增加陷波带宽，使其能重新跟踪到信号频率又具有较快的重新收敛速度。以一种基于Steiglitz-McBride方法的ANF(SMM-ANF)为例，分析了反馈修正策略，给出了流程和具体算法。仿真比较了格型ANF、SMM-ANF和反馈修正SMM-ANF的性能，给出了科里奥利质量流量计应用实例，结果表明：反馈修正SMM-ANF收敛速度稍慢于SMM-ANF，快于格型ANF，持续跟踪精度明显提高。

Vibration Frequency Tracking Method Based on Feedback Corrected Adaptive Notch Filter

The precision of vibration frequency estimation by adaptive notch filter (ANF) is not satisfactory all the time. The analysis pointed out that the fundamental reason is the ANF error converges to a local optimum value. A feedback corrected ANF is proposed referring to the idea of feedback control. According to the correlation between the input signal and the output signal, a factor evaluating the frequency tracking accuracy is designed to monitor the ANF work status. If the factor is less than a given threshold value, it’s considered the ANF lost vibration frequency. Then, it is demanded to enlarge the bandwidth of the ANF, so that the frequency can be re-tracked accurately. To insure the re-converging speed, a strategy of feedback adjusting the ANF parameters appropriately rather than re-initialization is applied. The ANF based on Steiglitz-McBride method(SMM-ANF) is tacked as an example to illustrate the feedback correction strategy. The signal processing flow and particular algorithm are also exhibited. The performance of Lattice ANF, SMM-ANF and the feedback corrected SMM-ANF are compared by simulations. An application instance of the proposed method in coriolis mass flow meter is given out briefly. Results show that the convergence rate of the feedback corrected SMM-ANF is little lower than original SMM-ANF, higher than the lattice ANF. The continual frequency tracking performance of the feedback corrected SMM-ANF is obviously better than the others.