COCrIP: Compliant OmniCrawler In-pipeline Robot
This work addresses the challenge of in-pipeline inspection and maintenance for industries like oil and gas, presenting an incremental improvement in robotic mobility within confined spaces.
The paper tackled the problem of designing a climbing robot for navigating small-diameter pipes with sharp bends by developing a modular robot with compliant foldable OmniCrawler modules, achieving holonomic motion and traction on slippery surfaces through numerical simulations and experimental validation.
This paper presents a modular in-pipeline climbing robot with a novel compliant foldable OmniCrawler mechanism. The circular cross-section of the OmniCrawler module enables a holonomic motion to facilitate the alignment of the robot in the direction of bends. Additionally, the crawler mechanism provides a fair amount of traction, even on slippery surfaces. These advantages of crawler modules have been further supplemented by incorporating active compliance in the module itself which helps to negotiate sharp bends in small diameter pipes. The robot has a series of 3 such compliant foldable modules interconnected by the links via passive joints. For the desirable pipe diameter and curvature of the bends, the spring stiffness value for each passive joint is determined by formulating a constrained optimization problem using the quasi-static model of the robot. Moreover, a minimum friction coefficient value between the module-pipe surface which can be vertically climbed by the robot without slipping is estimated. The numerical simulation results have further been validated by experiments on real robot prototype.