Measurement of Granular Surface Pattern in a Hopper by Ultrasonic Wave Sensor

Fundamental characteristics for pattern recognition of granular surface in a hopper by ultrasonic wave sensor was investigated experimentally for the purpose of developing the detector as a control unit. Results showed rize time of output voltage from the reciever affected directly the accuracy of measurement. Directivities of the sensing units have been improved by installing the conical shaped horns in front of both the transmitter and reciever. Experiments on the effect of the pulse wave length on the strength of its reflection from object indicated that duration time more than 300μsec was sufficient to reach the threshold level. Measurement error which was due to the irregular reflection from the particle surface and inner wall surface was reduced by arranging the four recievers around the emitter.