An Inspection Robot-Based Health Monitoring Method for Monorail Crane Tracks in Underground Coal Mines

Monorail crane track plays an important role in the auxiliary transportation system of coal mines. However, the current track defects mainly rely on manual inspection. It is difficult to carry out continuous and systematic global monitoring of the track. Therefore, this article proposes the health monitoring method for underground monorail crane tracks in coal mines based on an inspection robot, according to the health monitoring needs of monorail crane track conditions. First, we designed a track-dependent inspection robot with a modular and separable structure. Then, for the common health state problems of monorail crane tracks, we proposed a track misalignment detection method based on ultrasonic ranging and a track corner detection method based on machine vision, and investigated a defect localization method based on radio frequency identification (RFID). Finally, we carried out an experimental verification of the inspection robot system. The results show that the inspection robot can smoothly pass through ramps, turnouts, and curves with a maximum angle of 20°, the accuracy of misalignment detection is about 82%, the relative error of the track bending angle detection method is less than 20%, and the accuracy of defective track localization reaches more than 98%. The developed inspection robot system can complete the inspection and monitoring tasks of the monorail crane track condition, and provide a reliable means for the healthy operation and maintenance of the monorail crane track in the coal mine.