Proposal of an Automatic Method for Sorting Live Fish Using Underwater Helmholtz Resonance

Abstract

　This paper proposes an automatic live fish sorting system using underwater Helmholtz resonance. For the continuous measurement of live fish, water flow in a hose was used to transport the fish through a resonator. It was demonstrated that the volume of fish inside the hose was measured using a soft PVC hose. To improve measurement speed, the pure tone of the resonance frequency in the absence of fish was output and its amplitude was measured instead of the resonant frequency. The results showed that the amplitude value decreased as the fish’s volume increased. A prototype sorting system was constructed, and a success rate for sorting into large and small groups using goldfish was 87.5 %.