Multiple-Connected Variable Outer Diameter Pigs Using Pneumatic Artificial Muscle for Inspecting Narrow and Complex Pipeline, Including Many Bend Pipes

Abstract

This letter proposes a moving mechanism applied Multiple-connected Variable Outer Diameter PIGs (Multi-VOD PIGs) for in-pipe inspection. This study aims to inspect the inside of long, narrow, and complex piping. Related studies include wheeled, snake, and worm robots. However, these robots have large mechanisms for great traction. The Pipe Inspection Gauge (PIG) is a simple mechanism with a high output potential by in-pipe fluid pressure that allows for multiple connections. However, existing PIGs have the problem of friction with the inner wall of the piping. In this letter, we propose a Multi-VOD PIGs. The Multi-VOD PIGs can move through the piping while reducing the tension between Variable Outer Diameter PIGs (VOD PIGs) by Multi-VOD PIGs, thus increasing the inspection distance. In addition, the modeling of the generated force in the piping and the response of the piping pressure was conducted. To validate the effectiveness of the proposed Multi-VOD PIGs, verification experiments were conducted on the model and a simulated in-pipe inspection experiment using the Multi-VOD PIGs. To verify the effectiveness of the proposed Multi-VOD PIGs, a model was constructed, and validation experiments were conducted. Furthermore, based on the constructed model, Multi-VOD PIGs were developed, and in-pipe inspection experiments were conducted. The robot successfully inspected a 9200-mm-long, 12-bend simulated piping, whereas the previous study had inspected a 5-bend long-distance piping. These results indicate that the Multi-VOD PIGs can be expected to be used for the inspection of long-distance piping with many bends.