System for Monitoring Progress in a Mixing and Grinding Machine Using Sound Signal Processing

Ekkawit Wangkanklang,Yoshikazu Koike

doi:10.3390/mi12091041

Abstract

In this paper we present a system for monitoring progress in a mixing and grinding machine via the signal processing of sound emitted by the machine. Our low-cost, low-maintenance system may improve automatic machines and the industrial Internet of Things. We used the Pumpkin Pi board and Raspberry Pi, which are low-cost hardware devices, for recording sounds via a microphone and analyzing the sound signals, respectively. Sound data obtained at regular intervals were compressed. The estimated power spectral density (PSD) values calculated from the sound signals were related to the status of the material during mixing and grinding. We examined the correlation between the PSD obtained by the STFT and the particle distributions in detail. We found that PSD values had both repeatability and a strong relation with the particle distributions that were created by the mixing and grinding machine, although the relation between the PSD and the particle size distributions was not merely linear. We used the PSD values to estimate the progress remotely during the operation of the machine.

Highlights

Mortars and pestles have traditionally been used to mix and grind materials, such as rice powder, peanuts, and pottery
We proposed a method for monitoring the progress in a mixing and grinding machine
The power spectral density (PSD) values for peanuts decreased at the beginning of the process and increased when the peanuts and sugar formed a lump, and decreased again when the mixture became creamy

Summary

Introduction

Mortars and pestles have traditionally been used to mix and grind materials, such as rice powder, peanuts, and pottery. Machines are used for mixing and grinding to produce large quantities of high-quality ground materials. The Ishikawa mixing and grinding machine is used in industrial manufacturing processes [1]. For various types of materials, including those for electronic parts, chemical products, and art supplies, as well as some special materials, such as materials for solar batteries and fluorescent paint or gold powder. Systems for monitoring mixing and grinding while the machine operates are critical. Operators cannot remotely observe the progress of mixing and grinding

Methods

Results

Conclusion