Differential-drive in-pipe robot for moving inside urban gas pipelines

TLDR

Urban gas pipelines demand robots with high mobility and advanced control to navigate straight sections, elbows, and branches. The study introduces MRINSPECT IV, a miniature differential‑drive in‑pipe robot, and proposes a wheel‑speed modulation control method that works without complex sensors. MRINSPECT IV employs a 3‑D differential‑drive wheel arrangement that steers through straight, elbow, and branch fittings, uses mathematical models to predict motion, and is validated by experiments. MRINSPECT IV was successfully built for inspecting 4‑inch urban gas pipelines.

Abstract

Pipelines for the urban gas-supply system require a robot possessing outstanding mobility and advanced control algorithms, since they are configured with various pipeline elements, such as straight pipelines, elbows, and branches. We present a comprehensive work for moving inside underground urban gas pipelines with a miniature differential-drive in-pipe robot, called the Multifunctional Robot for IN-pipe inSPECTion (MRINSPECT) IV. MRINSPECT IV has been developed for the inspection of urban gas pipelines with a nominal 4-in inside diameter. The mechanism for steering with differential-drive wheels, arranged three-dimensionally, allows it to easily adapt to most of the existing configurations of pipelines, as well as providing excellent mobility during navigation. After carrying out analysis for fittings in pipelines, mathematical descriptions of their geometries are presented, which make it possible to estimate the movement patterns of the robot while passing through the fittings. Also, we propose a method of controlling the robot by modulating speeds of driving wheels that is applicable without sophisticated sensory information. To confirm the effectiveness of the proposed method, experiments are performed, and supplementary considerations on the design of the in-pipe robot are discussed.