Position-sensorless for wire rope distance measurement and nondestructive testing

Devices used for nondestructive testing of wire rope often include a guide wheel, which is connected to an encoder to measure the running distance of the wire rope and to provide information about defect positions. However, in use, problems with the guide wheel such as contact jittering, slipping, idling, and bouncing cause encoder pulse loss, which affects the location measurements and quantitative analysis of the defects. Also, the wire rope running at high speed is a safety problem. However, these issues can be avoided by using the unique winding of the wire rope to provide a strand wave signal. Using wave signal processing, the distance traveled by the wire rope can be measured. Then, a phase-locked loop locks and multiplies the frequency of the strand wave signal. The multiple-frequency signal is used as a trigger signal for equal distance sampling of the wire rope. This method not only replaces the use of guide wheels and encoders when the wire rope is running at uniform velocity, but also improves the precision of the positioning and quantitative analysis of defects.