SPIRA: Small Gas Pipeline Inspection Robot with Spiral Leg-Wheel Mechanism and Single Bending Joint
Mitsuhiro Kamezaki, Kaoru Yamaguchi, Wen Zhao, Kento Yoshida, Toshitaka Koike, shota miyake, Shigeki Sugano
AI summary
Problem
Conventional pipe inspection robots cannot simultaneously meet the critical requirements for inspecting 50-mm gas service lines, including high speed, reverse travel, and navigation through complex networks of elbows, tees, and sockets.
Approach
The robot uses two spiral leg-wheel units with spring pantograph legs to maintain wall contact and adapt to diameter changes, combined with a single central bending joint to steer through turns and select paths at junctions, all controlled by just three motors.
Key results
- Achieves 100 mm/s travel speed in straight pipes
- Navigates 90° elbow joints and tee junctions
- Passes through 3-mm socket steps and 12-mm diameter changes
- Enables reliable reverse travel and vertical pipe climbing
Why it matters
Enables rapid, non-invasive inspection of critical 50-mm gas service lines, improving infrastructure safety and reducing costly road excavation for maintenance.
Abstract
Gas pipelines damaged by aging or earthquakes need a robotic system that can quickly inspect 50-mm-diameter service lines, consisting of horizontal and vertical pipes connected by elbow joints, tees, or sockets, from the inside. However, conventional pipe inspection robots do not target 50-mm pipes and various pipe types or lack sufficient speed and a reverse function. Thus, this study de- velops an in-pipe inspection robot, SPIRA, capable of traveling through 50-mm pipelines while meeting the above requirements. SPIRA has three wheels inclined at 30 degrees to the horizontal, arranged around a cylinder. The cylinder is rotated by a motor around the robot’s axis, and the wheels move in a spiral motion while pushing the pipe wall, enabling the robot to move stably and quickly. To overcome socket steps of up to 3 mm and diameter changes in elbow joints, the cylinder and each wheel are connected by a leg with a spring pantograph mechanism. SPIRA has two trav- eling units linked by a bending joint with a servomotor. When the front and rear parts rotate clockwise (counterclockwise), SPIRA moves forward (backward). When both units rotate in the opposite direction, only the central part of SPIRA rotates on the spot, chang- ing the bending direction so that SPIRA can select any travel direc- tion in a tee. We evaluated the travel performance of SPIRA in a pipeline of horizontal, vertical, elbow joints, tees, or sockets, and found that it could smoothly travel through the pipelines, which is difficult for conventional robot systems to achieve.