Vehicle Speed Detection And Application Based On Short-pitch Dual-node Geomagnetism Sensor

Vehicle speed is one of the key indicators that intuitively reflect the state of road traffic.It is an indispensable indicator for the construction of modern intelligent transportation systems and even smart cities.Traffic managers can judge traffic congestion based on vehicle speed and achieve reasonable speed limit setting and signal control.In this paper,two identical geomagnetic chips are integrated into the Smart Road Stud separated by less than 10 cm,and they are placed in the middle of the lane and on the lane line respectively.The vehicle speed detection algorithm of short-distance dual-node geomagnetic detector under different working conditions is studied.On the basis of vehicle speed detection,the acquisition of other traffic parameters and the application of short-distance dual-node Smart Road Stud are studied,which realizes the engineering objectives of miniaturization,easy installation,high precision and low cost.Firstly,this paper analyzes the working principle of geomagnetic sensor and the principle of vehicle speed detection,and studies several existing geomagnetic vehicle speed detection methods,including several single and double node speed detection algorithms,and analyzes the advantages and disadvantages of the two detection methods.In addition,the hardware structure and speed measurement principle of the short-pitch dual-node geomagnetic detector are briefly described.Second,the short-pitch dual geomagnetic data is preprocessed.Using wavelet denoising to filter out signal noise,the proposed adaptive background-free waveform extraction algorithm can ensure the speed detection of queues in adjacent lanes,eliminating background value drift caused by various reasons;because the two geomagnetic sensor parameters are incomplete consistently,after filtering the data collected by the two geomagnetic sensors and removing the background,the consistency processing is performed to reduce the influence of poor hardware consistency.Aiming at the problem that the overall delay of two waveforms with the same name is poor,a local optimization algorithm is proposed to decompose the two waveforms into multiple band pairs.Two similarity evaluations are introduced to automatically identify the well-following band pairs.For the problem of low signal time resolution,this paper uses local interpolation and local fitting to improve the resolution in software.Calculate the time difference between the vehicle passing through the two-node geomagnetism,and then get the vehicle speed.The actual road section is selected to carry out experiments and verify the proposed algorithm.The results show that the average accuracy of the two algorithms is above 90% when the sensor is placed in the middle of the lane,which is worthy of practical application.The detector is placed on the lane line,and the driving speed of the vehicle is detected by the same method.The average speed detection accuracy of the section in one minute is 96%,which can be used as a basis for judging traffic congestion.Finally,the vehicle speed detection value is used to calculate other traffic parameters,including vehicle type,time occupancy rate,and headway distance.The application scenarios of short-distance two-node geomagnetic intelligent spikes are analyzed,including road congestion degree evaluation model and anti-tailing warning mechanism.