基于方格靶标的沥青混合料颗粒群变形跟踪方法

A Method for Tracking Deformation of Asphalt Mixture Particles Based on Grid Target

为探测沥青混合料内部颗粒群的变形情况,提出了一种基于方格靶标的抗干扰能力强、精度高、多目标跟踪的颗粒群变形分析方法。首先,将混合料车辙试件制成切片,在切面颗粒上印制5×5黑白相间的方格靶标,采集切面图像,捕捉该图像中的靶标图案,计算靶标中心点的位置坐标及靶标方位角,记录为颗粒的初始位姿。然后进行车辙试验,反复轮碾后,再次采集切面图像,提取颗粒群变形后的靶标图案,并由其计算靶标中心点位置及方位角,作为颗粒加载后的位姿。最后通过对比颗粒在两种位姿下靶标中心的位移量和靶标转角实现颗粒内部任意点的变形计算。在捕捉靶标的过程中,利用平行方格靶标明显的几何特征,使用边缘检测、投影技术,根据靶标图像旋转角度与边缘强度投影累加峰值的关系曲线,获得靶标角点阵列初始坐标及靶标角度候选值。在靶标位姿参数提取方面,主要通过角点阵列的亚像素搜索实现靶标中心点坐标高精度计算,结合靶标与集料纹理的图像相关性分析技术,完成靶标角度确定。试验结果表明:该方法能够实现颗粒群变形跟踪,为分析沥青混合料在荷载作用下内部颗粒群运动规律提供了一种有效的分析方法。

In order to detect the deformation of particles in asphalt mixture, a method for analysing deformation of particles based on grid target is proposed. This method has the advantages of anti-jamming capacity,high precision and multi-target tracking. First of all,the rutting specimens of the mixture are sliced into sections,and a 5 × 5 black and white grid target is printed on the cut plane particles. The image of the cut plane is collected,the target pattern in the image is captured,and the coordinates of the center position and the azimuth angle of the target are calculated,which is recorded as the initial position of the particle.Then,rutting test is carried out,after repeated roll grinding,the image of the cut plane is collected again,the target pattern after particle group deformation is extracted,and the center position and azimuth angle of the target are calculated as the particle orientation after loading. Finally,the deformation calculation of any point inside the particle is realized by comparing the displacements of the target center and the target rotationangles in 2 positions. In the process of capturing the target,by using the obvious geometric characteristics of the parallel grid target plate,edge detection and projection technology,the candidate values of the corner array initial coordinates and the target angle can be obtained according to the curve of relation between the target image rotation angle and the edge strength projection accumulation peak. In terms of target position parameter extraction,the sub-pixel search technology of corner array is used to achieve the high accuracy calculation of the target center point coordinates,and then the target angle is determined combining with the technique of image correlation analysis of target and aggregate texture. The experiment result shows that this method can realize tracking deformation of particles,which provides an effective method for analyzing the motion of the particles in asphalt mixture under the action of load.