Dynamic simulation and experimental research on the motion of odometer passing over the weld

• The motion of the odometer passing over the welds was investigated.
• Mathematical and simulation models were presented to describe the motion of odometer.
• The reason for the accumulative errors of the odometer was presented.
• Effects of pigging velocity on the error of the measured are discussed.
• Research results indicate that the odometer error can be divided into two conditions.

Odometer wheel system, designed to measure the traveled distance and the instantaneous velocity of the intelligent inspection pig in operation, is an important part of the pig to define the position of pipeline defects. High accuracy positioning of pipeline defects can greatly improve the pipeline maintenance efficiency and highly reduce the costs. However, due to the peculiarity of its construction, the odometer is prone to unbounded accumulative errors and pipeline weld is the main reason. As a result, research on the motion and accuracy of odometer system is essential. In this paper, the motion of the odometer passing over the weld was investigated. Mathematical and simulation models were presented to describe and analyze the errors of the odometer, which was verified by the experiment. Research results indicate that the error of the measured distance can be divided into two conditions. At low velocity, the measured distance is larger than the actual distance, while the measured distance is smaller than the actual distance at high velocity. The results in this paper can provide better understanding of the accumulative errors of the odometer, and contribute to find a way to improve the accuracy of the odometer wheel system.