A new time domain filtering method for calculating the RMS value of vibration signals

In the process of vibration signal analysis, the relative mean square (RMS) value of vibration signal is an important index, which should be measured by a frequency domain method or time domain method. In the paper, the FFT is applied to obtain the RMS value of amplitude at each frequency signal, and then the total relative mean value is also calculated the whole vibration signal by the time domain algorithm. From the results, it can be found that the error is easily to be produced due to larger T cycle in low frequency process. So, by adding a low filter before the calculation of the RMS value, a new modified method is proposed to eliminate the error caused by the noninteger times period. The simulation signal is also established by MATLAB software, and it is proved that the new method can effectively improve the accuracy of the RMS value.