In order to avoid subjective estimation of the direction of groove by using a tester in the four-ball friction test, an automatic wear angle detection method based on gray difference of inclination angle is proposed in this paper. First, the gray difference between the pixel and its W × 2W neighborhood pixels is acquired, in which each neighborhood pixel corresponds to an inclination angle. Second, a row’s grayscale difference of inclination angle is calculated, which is the sum of grayscale difference of all pixels in the same row with the same inclination angle. Third, the inclination angle corresponding to the minimum row’s grayscale difference is defined as the approach angles. Finally, the first t approaching angles with the highest frequency determine the wear angles. Compared with true angles determined manually, the simulation results of 200 samples show that the average absolute error is 2.1238° and the average running time is 1.3 s per frame. The influence of the algorithm parameters on detection precision is also analyzed.

中文翻译：

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基于倾斜角差的四球摩擦试验磨损图像的沟槽检测方向

为了避免在四球摩擦试验中使用测试仪主观地估计沟槽的方向，提出了一种基于倾斜角灰度差的自动磨损角检测方法。首先，获取像素与其W  ×2 W邻域像素之间的灰度差，其中每个邻域像素对应一个倾斜角度。其次，计算一行倾斜角的灰度差，它是同一行中所有具有相同倾斜角的像素的灰度差之和。第三，将与最小行的灰度级差相对应的倾斜角定义为接近角。最后，第一个牛逼频率最高的接近角决定了磨损角。与人工确定的真实角度相比，对200个样本的仿真结果表明，平均绝对误差为2.1238°，平均运行时间为每帧1.3 s。还分析了算法参数对检测精度的影响。