Flow measurement using Kalman filter for smoothing vortex shedding frequency

A vortex signal is usually superimposed with noise, such as plant noise and measurement noise. Therefore it is proposed to estimate the vortex shedding frequency with a recursive filter, considering the plant and measurement noises. In this paper, a digital algorithm is implemented in a microcontroller to determine the vortex shedding frequency of a vortex flow meter in a turbulence flow range. The first step of the presented algorithm is to estimate the preprocessed vortex shedding frequency using a zero-crossing technique. After the estimation, the vortex shedding signal is smoothed with a Kalman filter. The test results show that this algorithm is able to compute values of the flow rate accurately in a turbulence range.