| 摘要 |
<p>A parking aid for a motor vehicle 1 comprises at least two sensors 5. Each sensor 5 transmits and receives ultrasonic pulses. Initially all transmitters transmit simultaneously on different frequencies, sequentially or in groups (e.g. front and rear). When one or more receiver(s) receive echoes reflected by object 7, only the corresponding transmitter operates. This enables more effective tracking of object 7. Time of flight indicates range. A pair of sensors detects the objects direction. Every 10 or 20 measurement cycles, all transmitters transmit once. The sensor may have a damped oscillating (vibrating) membrane driven by a piezo-electric element.</p> |
