Bioinspired untethered electromagnetic pipe-crawling robot.

In pipe systems, the emergence of pipe-crawling robots (PCRs) has attracted significant attention for pipe inspection and repair applications. However, conventional PCRs are bulky and heavy, limiting their speed and adaptability, particularly in confined spaces. Additionally, their reliance on tethered power and signal transmission restricts mobility due to the constraints of external cables. To address those challenges, we propose a novel compact, untethered PCR powered by a battery-driven electromagnetic actuator inspired by earthworms. The optimized overlapping design of the magnet and coil enhances driving force, effectively supporting the robot and its onboard battery. We design a control module integrated into a printed circuit board (PCB) to achieve untethered functionality. To further enhance crawling efficiency, we incorporate bioinspired bristles with anisotropic friction at the robot's head and tail to ensure stable anchors during locomotion. Integrating electromagnetic actuator, PCB, and bristles, our bioinspired PCR achieves a lightweight, compact, untethered design capable of fast crawling, even in vertical orientations. Finally, our untethered PCR bears a 12 g onboard battery for both horizontal and vertical crawling, achieving remarkable crawling speeds of 55 BL min^-1(48.5 mm s^-1) horizontally and 16.3 BL min^-1(13 mm s^-1) vertically.