Measurement of Granular Surface Pattern in a Hopper by Ultrasonic Sensor (The 2nd Report)

The ultrasonic sensor has been developed as a detecting element to recognize the granular surface pattern in a hopper. The equipment and the measuring algorithm were improved on the basis of the results obtained from the original system. Narrow directivities of the emitter and the receiver have reduced the measurement error due to the echo from the inside hopper wall. Output voltage of the receiver was enhanced to shorten the lag time which emerged in the signal level sensing circuit. The inclination angle of the surface was detected by the swinging method, which also decreased the receiving error of the reflected wave. The resolution of the time measurement was one microsecond utilizing the time counter circuit. Experimental results were shown for the fundamental surface condition and for the application to a hopper system.