JPS5621204A - Direction control unit for agricultural machine by ultrasonic wave distance detection - Google Patents

Abstract

PURPOSE: To eliminate the external disturbance due to reflection by object at the back of measured object, by providing the inhibit gate 20 based on the distance limit gate 22.

CONSTITUTION: Ultrasonic waves are transmitted from the transmitter 12 fitted to the float 10 toward the direction orthogonal to the progressing direction of the rice- plant implanting machine 1, and the 1st reflection signal reflected from the implanted rice-plant 13 is received at the transmitter 12. Further, since the amplitude of the received signal is smaller than that of the transmitted signal, the signal switching circuit 17 transmits the received signal to the amplifying circuit 19. Since the inhibit gate 20 is used only during the time slightly longer than the time when the ultrasonic wave signal is transmitted and received, the first reflection signal only can pass through the inhibit gate 20 and it is detected at the detection circuit 21 and fed to the time width voltage conversion circuit 23. On the other hand, based on the difference between the time difference between the reference pulse signal and the reception signal, and the set delay time difference from the reference pulse signal of the measured distance 1 from the output circuit 25, the direction control circuit 26 sets the direction of progress.

COPYRIGHT: (C)1981,JPO&Japio