测距系统作为汽车防撞技术的核心组成部分，需要具备良好的实时性和高度的准确性。比较目前应用于汽车领域的测距方法，重点介绍了机器视觉技术，并针对它响应速度慢的缺点，引入了激光技术进行辅助测距。通过采用激光照射在前方障碍物上形成的激光光斑作为系统的特征点，达到了快速定位障碍物的目的，显著地提高了系统的反应速度以及恶劣天气下的适用性。实验结果显示在精度和反应速度两方面都满足了测距系统的实时性要求。相对于传统机器视觉技术在测量精确度上有68%的提升，在反应速度方面有54%的提升。

As a key component of car collision-avoidance system, distance measurement puts emphasis on response time and accuracy. Several ranging methods applied in automobile area are discussed. In particular, machine vision is introduced as a popular way in distance measurement. To improve its response time and usability under bad weather, laser is adopted to locate obstacles. Experimental results show that the system can meet the ranging requirement of collision avoidance. Compared to traditional machine vision, the combined way can reduce 54% response time and 68% deviation.