Study on rail gauge detection systems based on image sensors
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摘要: 传感器在铁路安全维护方面应用广泛。为了实现实时在线轨距测量,将激光技术与CCD图像式传感器相结合,建立车载轨距机器视觉检测系统。首先介绍系统的构成与工作原理,并提出基于去噪前置与距离变换算法的快速轨道轮廓中心线提取方法。然后采用强对比度拉伸和指数变换的方法进行图像增强,并结合高斯平滑与动态感兴趣区域对图像进行快速去噪前置处理。最后对图像进行精确阈值分割处理,采用距离变换的方法得到轨道轮廓中心线并定位轨距测量点。结果表明,该系统检测精度满足-1mm~+1mm,图像帧处理速率为14.35m/s。轨距机器视觉检测系统满足实时在线轨距检测对系统鲁棒性、检测速度和精度的要求。Abstract: Sensors are widely used in railway safety maintenance. In order to achieve real-time online gauge measurement, an on-board machine vision system of gauge detection was established with the combination of laser technique and CCD image sensors. Firstly, the working principle and structure of the system were introduced. A fast extraction method of rail contour centerline was proposed based on pre-noising and distance transform (PNDT) algorithm. Then, the image was enhanced with the strong contrast stretching method and exponential transform method. Fast pre-noising processing was conducted with the combination of Gaussian smoothing and dynamic region of interest (ROI). Finally, precise threshold segmentation processing was carried out for the images. The rail contour centerline was gotten and the gauge measurement point was located with the distance transform method. Experimental results show that the detection accuracy of the system is -1mm~+1mm and image frame processing speed is 14.35ms. The system can meet the requirement of the robustness, detection speed and accuracy in real-time online gauge detection.
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Keywords:
- laser technique /
- gauge detection /
- contour centerline /
- distance transform /
- threshold segmentation /
- sensor /
- machine vision
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