为了使超声波传感器能在动态环境下定位,要求单超声波接收头能测量多个目标.首先分析了超声波发射头产生的超声波特点,据此推导出接收信号的波形表达式.其次根据接收信号特点,系统标定时用接收信号包络峰值的0.5倍作阈值,而测量时用小阈值,以防止距离信息丢失.最后用C8051F021单片机设计了单接收头多目标测距系统.在2目标与接收头距离之差大于30cm以上时能较精确地测量出2个距离.
A ultrasonic receiver is required to measure a few goals in order to enable localization under the dynamic condition. Firstly the characteristic of ultrasonic from a transmitter is analyzed and then the wave expression of receiving signal is deduced. Secondly a half of receiving signal peak is adopted as threshold in calibrating system and a low threshold is used in measure to avoid losing information. Finally a C8051F021 chip is used to design multi-goal measure system of single receiver. Two distances are measured accurately when the interval of the distances from two goals to the receiver is more than 30 cm.