一种基于LMS的振动信号相位差自适应无偏估计方法及应用

LMS based phase difference adaptive unbiased estimation method and its application

针对振动信号相位差估计问题,提出了一种基于LMS的自适应无偏估计方法。该方法通过一路信号与其正交的三角运算来配准另一路信号,相位差的正切值等于两个配准系数之比;根据均方误差最小原则对配准系数进行迭代更新,从而实现相位差自适应估计;理论推导出噪声引起的估计偏差,并据此对估计结果进行偏差补偿,实现相位差无偏估计,给出了补偿公式和方法流程。实验结果表明:该方法能准确估计出两路同频振动信号相位差,经偏差补偿后估计精度显著提高;在相位差发生突变时,能进行快速跟踪测量,具有较好动态测量特性;该方法在变化流量下科氏流量计振动信号相位差估计中的应用,验证了方法的工程实用性。

For phase difference estimation of vibration signals,a LMS based adaptive unbiased estimation method was proposed.In the method,one of the two signals and its orthogonal signal were used to synthesize a new signal which is seen as the estimation of the other signal and the phase difference of the two signals was equal to the ratio of two matching coefficients.The coefficients were adaptively updated to minimize the mean square matching error and then to realize the adaptive estimation of phase difference.The estimation bias resulted from noises was theoretically derived.For improving the precision,the estimated results were compensated according to the estimation bias to obtain an unbiased estimation of phase difference.The compensation formula and process of the proposed method were given out.The experimental results show that the proposed method is able to accurately estimate the phase difference of two signals with the same frequency.The precision of estimation is significantly improved by bias compensation.The proposed method has a good dynamic measurement characteristic which makes it still available when mutations of the phase difference occur. The application of the proposed method in measuring the dynamic phase differences of Coriolis flow meter signals in the varying flow situation verifies its engineering practicability.