Application of Image Processing to Health Monitoring for Wire Rope of Lift systems

Rupture of wire ropes is one of severe accidents in lift systems.  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 difference among inspectors.  Therefore development of a new monitoring system for the diameters and red rust is required in order to ensure qualities of the inspection and manage the inspection data efficiently.  Meanwhile image processing technology has recently been applied to various industries such as automatic driving vehicles.  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.  This paper describes image processing method for inspection of wire rope and results of verification tests.  Photography condition suitable for monitoring was investigated.  As a result, the measurement error was less than 1% by adjusting photographing condition.