Design Of Ultrasonic Detector For Traffic Data Of Vehicles

The subject of this design is a suspension-type of ultrasonic detector for vehicles' traffic data. In principle, ultrasonic sensors are suspended over a road, which keep emitting pulse signals periodically to nearby and feed back waves to decide existence of any obstacles, thus to detect the speed, height, length, different sizes (heavy, medium and small) of moving vehicles and accumulative flow as well as length of motorcade. Optionally, it can be applied to multitude driving lanes simultaneously for traffic data. By integrating and analyzing these measured data, the necessary figures concerning traffic flow may be obtained, which are fundamental basis guiding road buildings.This design has distinctive technical features as follows:1. Applied Multi-sensor construction. Well-calculated distance and crossing angles between sensors aiming at a same target makes it possible to acquire more accurate back waves than single sensor construction. Consequently, error rate is reduced significantly.2. Able toe stablish the d arum 1 ine automatically r egardless o f t he h eight o f s ensor suspended above the road. The obstacle is detected based on the back wave reflected from road surface.3. Arranged signal activating lock circuit and time-base control circuit in the sound wave receiving circuit to take the initial signal of back wave as the valid one in the cycle, thus to improve the ratio of signal vs. noise and detective precision.4. Integrated disturbance-resistant datum module (digital filtering) to strengthen the anti-disturbance capacity of the system.5. Able to detect the traffic data from multiple lanes simultaneously by connecting several detecting units (sensors) with one central processing unit.6. Designed fuzzy recognition module in the software to screen out the disturbancefrom pedestrians, non-driven vehicles and motorcycles for higher counting accuracy.Although there are many literatures describing ultrasonic detector for traffic flows, none of the same category has referred the techniques applied in the design herein such as multi-sensor construction, automatically establishing datum line regardless of suspension height, digital filtering and multi-lane detection as well as measuring length of motorcade.