Health Monitoring System for Wire Rope Using Image Processing

Rupture of wire ropes is one of the potential severe accidents in a lift system. Before rupture by aging degradation, diameter of wire ropes decreases and surface of wire ropes is rusted. Thus diameters and red rust of wire ropes should be checked in periodic inspections of lift systems in Japan. The diameters are usually measured by using vernier calipers or scales, and red rust is checked with eyes, so there are errors and differences among inspectors. Therefore development of a new monitoring system for diameters and red rust of wire ropes is required in order to maintain the quality of inspection and efficiently manage inspection data. This paper proposes and constructs a health monitoring system for wire rope using image processing. The system consists of a digital camera and a computer. The digital camera takes a photograph of a wire rope and the photograph is analyzed by the computer. The diameter is calculated from the number of pixels of the rope, and red rust is detected by resolving the colour of the photograph into RGB data. Image processing method and examples of inspection are reported in this paper. As a result, the measurement error was less than 1% by adjusting photographing condition.