| Summary: | 碩士 === 國立宜蘭大學 === 生物機電工程學系碩士班 === 101 === This research is aimed at developing a fruits as well as vegetables volume sorting system, which is based on a Helmholtz resonator. This system is a dry type and non-contact measurement system. In addition, it can be used to measure the volume of water-soaking-forbidden objects. The principle of Helmholtz resonator is based on the fact that its acoustic resonant frequency is a function of cavity volume. When an alien material is inserted into the cavity, the total air volume inside the cavity decreases, resulting in the increase of its acoustic resonant frequency. An automatic striking mechanism composed of three hammers was designed to induce the acoustic impulse responses, and a Singular Values Decomposition (SVD) algorithm was applied to extract these resonant frequencies consecutively. The averaged resonant frequency was then used. An air-sealed conveyor system was fabricated to transport each fruit for measuring its resonant frequency. For grading purposes, a mechanical-electrical system with air-cylinder, wood-slider, and Programmable Logic Controller (PLC) was also designed. The averaged successful rate of sorting fruits reaches 85% for both regular-shape fruits (guava and apple) and irregular-shape fruits (yam and custard apple), very close to the requirement of 90% successful rate for a commercial grading system. The top speed of the developed system is 35 fruits/min.
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