Characteristic analysis of a novel in-pipe driving robot

• A modular helical drive in-pipe robot is developed.
• Inchworm in-pipe robot motion planning.
• A compliant mechanism like in-pipe robot.
• An outstanding bend negotiation in-pipe robot.

Gas and liquid pipelines are all around us in today’s society. The frequent inspection and maintenance of such pipeline grids is very important, especially for urban areas where there are dense populations. Many driving mechanisms for in-pipe crawling have been reported in previous studies. In this paper, a novel in-pipe drive design is presented. The proposed design uses modular helical drives. In between helical drives is a conic coil spring that allows extension and retraction. Since conic springs can be designed with telescopic feature, the proposed design can be made very compact. Furthermore, the proposed design also has much better mobility when turning a bend due to its flexible body (conic springs make the inchworm robot a compliant mechanism). The proposed design can be controlled with three modes of motion: synchronized motion (for small load), inchworm motion (for medium load), and rigid motion (for heavy load). Analysis on gripping force, locomotion force, together with experimental results will be presented as well.