Research And Implementation Of Speed Detector By Loop Induction Matching

Traffic accidents increase rapidly because of vehicles exceed the speed limit, which not only cause huge economy losses, but also make many people lose life. Therefore how to detect vehicle's velocity precisely becomes an important problem for controlling traffic violation. Loop detector is one of the most common tools for traffic information collection and traffic situation classification.However it has low precision in detecting velocity and can't satisfy the requirement of traffic management to control speed-exceeding.After analyzing the typical loop detectors in domestic and foreign range, this paper devises a vehicle's velocity detection system by matching loop-coil signal and illuminates the scheme in detail. Matching the frequency data by correlation, then searching the "transit time" paralleled by peak data and figuring out vehicles'velocity is the main principle of this system. The system can compensate the deficiency of present loop detectors and has high precision in detecting velocity. This paper introduces the system structure and designing principle, expatiates the designing methods, designing process and related key techniques of this system.This paper devises a data collecting and testing system based on industrial computer, achieves software designing and testing, and improves the signal converting circuit of data collecting module which is controlled by CPLD.On the top of these work, a whole designing scheme using DSP for detecting vehicle's velocity is given. Preliminary design of the principle diagram has been achieved, and this paper simulates the process of velocity detection in the software environment at last.The simulation and experimental results indicate that the hardware platform and relative software system can solve the velocity detection problem of loop detector effectively, and can satisfy the requirement of velocity detection in traffic management.