A Modular Soft Pipe-Climbing Robot With High Maneuverability

Pipeline is widely deployed in infrastructures, which raises a great demand of pipe-climbing robots to provide pipe-inside inspecting and platform delivery. Soft pipe-climbing robots (SPRs) are intrinsically flexible and able to operate within complex, narrow and curving pipelines more effectively than their rigid counterparts. In the state of the art, the existing SPRs have demonstrated their performances in fixed-diameter pipes that are placed in static-fluid environments, which however does not show their full potential. In this article, we propose a modular design methodology for SPRs that are expected to operate inside complex pipelines. The robot's torso is composed of three PSAs in parallel, which can realize axial elongation as well as omnidirectional bending with pressurized air. The PSA-based tentacles will elongate after inflation to contact and hold the pipe wall using their silicone pads. Furthermore, the slim tentacles and compact torso results in quite small cross-sectional occupation ratio and subsequently low windward resistance from the liquid in the pipeline, which ensures the robot's high passivity in fluid. The proposed robot can adapt to and work in diverse pipelines with complex fluid conditions, such as horizontal and vertical straight, as well as curved pipes with varying diameters, with and without loads, in still and dynamic water flows. In addition, the robot, whose weight is 50 g, can achieve a fast speed of climbing (up to 15.0 mm/s in open air) and high load-carrying ability (up to 1500 g) due to the quick response of the tentacles and large elongation ratio of its body. The experimental results have proved the high maneuverability of the developed SPR.