| 摘要 |
<p>The sensor detects the size and shape of nearby plants. A plurality of sensing units 29a-c each sense the presence or absence of plants in a narrow field of view by transmitting ultrasonic pulses which are reflected to the transmitting sensing unit. Multiplexing the sensing units prevents a reflected pulse from developing signals in sensing units near the transmitting sensing unit. The sensing units may be used to control the supply of liquid fed to spray nozzles 28 to ensure that only areas containing plants are sprayed. <IMAGE></p> |
