【摘要】 根据超声测距和Ｄｏｐｐｌｅｒ原理，采用微机控制测定两同向行驶车辆的车距及相对速度，实时判断，及时决断是否刹车和报警，以有效防止撞车事故的发生。更多还原

【Abstract】 In this paper, according to the ultrasonic ranging and Doppler principles, a microcomputer-based controlling system is developed to measure the distance and relative speed between two same direction running automobiles. The system can be used to alarm the drivers to break instantly so that it can efficiently guard against the collision accidents.更多还原