| 摘要 |
<p>A method and apparatus of recognizing the presence of a passenger in front of a door of a transit vehicle comprises direct-ing an ultrasound transmitter/receiver at a volume of space adjacent the door, emitting an ultrasound pulse into the empty volume, record-ing and integrating intensity of the echoes and storing the integrated value as a standard value, repeatedly emitting an ultrasound pulse into the volume, and comparing the integrated values to the standard value.</p> |
