| China’s highway mileage has ranked first in the world currently.With the increase of highway mileage,the demand for pavement crack,flatness,rut and damage detection will increase gradually.At the same time,with the wide application of vehicle controllable suspension system and ABS,it is also necessary to obtain the road roughness in front of the vehicle in real time and accurately.Therefore,the prediction of the road information in front of the vehicle can not only provide the basis for the detection and maintenance of the road,but also combine with controllable suspension system,ABS and other technologies to improve the driving stability,comfort and safety of the vehicle.In this paper,the key technology of pavement elevation measurement based on line structured light is studied as follows.Firstly,the structures and principles of the three common line structured light measurement system are studied,and a new line structured light measurement system is designed according to the characteristics of the test object in this paper.The laser is installed on the left side of the system to project the laser longitudinally,and the camera is on the right to shoot the longitudinal laser line of the road in front of the vehicle.This structure can meet the needs of this paper to predict the road information in front of the vehicle.Secondly,the common algorithm of extracting the center line of laser stripe is analyzed.Aiming at the problem that the line structure light is unevenly distributed and easily affected by the environment,a method of extracting the center line of laser stripe based on the quadratic smoothing algorithm is proposed.First,the region of interest in the collected image is cropped to reduce the computational cost of the center line extraction of laser stripe;then the initial value of the center line of laser stripe is extracted by the gray center of gravity method,and the big bulge and burr of the initial position of the center line of laser stripe are smoothed twice by the mean method;and the small bulge and burr of the center line of the laser stripe are smoothed by the Savitzky-Golay filtering algorithm eventually.The experimental results show that compared with the gray center of gravity method,this method can extract the center lines of four typical laser stripe on 1280 pixel × 720 pixel image,the speed and accuracy is increased by 2.40%-22.57%and 19.15%-44.87%respectively,and it is less affected by the change of light intensity,which can meet the requirements of strong real-time,high accuracy and good stability.Then,two common models of linear structured light measurement system are studied.According to the structure and principle of the line structured light measurement system designed in this paper,the relevant geometric parameters of the measurement system are optimized and determined,and a method of directly measuring the elevation of the road surface by calibrating the standard block is proposed.The experiments show that the absolute error range of static measurement is-0.4mm～0.5mm and the relative error range is-2.5%～1.5%at 4～5m in front of the measurement system,and the accuracy is high,which can meet the needs of road detection.Finally,the influence of body attitude changes on road elevation detection is studied,the image errors caused by body attitude changes are analyzed,and the road elevation detection errors caused by body attitude changes are calculated.Then a Kriging agent model is constructed based on this,a method of eliminating the body attitude error based on the Kriging agent model is proposed.The accuracy of the model is verified,and the result shows that the accuracy is high.In addition,the dynamic experiment of vehicle body attitude change is designed.The experimental results show that the road elevation measurement error caused by vehicle body attitude changes is consistent with the trend of theoretical analysis error change,and the error size under different attitude changes is similar.The research results of this paper can be used to predict the road roughness,grade and other road information in front of the vehicle.At the same time,it has reference value and guiding significance for semi-active control of controllable suspension. |
