基于时间比例放大原理,研究与设计近距离(小于70 m)的汽车追尾防撞红外测距系统。时间比例放大是微小时间测量的有效方法,通过电流幅值不同的恒流源使电容器充、放电,若电容器的充、放电荷量相等,就可采用通用微处理器实现微秒级的短时间精确测量。给出了时间比例放大测量原理,红外测距系统关键电路和核心控制程序流程图的设计方法。测距系统的实际测试结果表明研究成果有效,测距精度达到±1 m,适应于汽车追尾防撞。

A close (less than 70 metre) active infrared ranging system of vehicle anti-collision has been studied and designed which is based on the principle of the time of proportion amplifying. The time of proportion amplifying is the effective method to measure a little time,which is based on the charging and discharging of the high-precision capacitor with the two different constant-current sources.If the charge of the capacitor equal to the discharge, a universal MCU can be used to realize the measurement of time of μs precisly. The measuring principle of the time of proportion amplifying, the key circuits and the design of the core programming flowchart have been showed. The practical test results of ranging system show that the effort is effective and the precision is ±1　m, therefore, the system is adapt to vehicle anti-collision.