Abstract: This paper presents an untethered pneumatic soft robot which can crawl both in horizontal and vertical pipes with differ-ent sizes and cross sections. This robot uses modular origami inspired soft-rigid hybrid actuator to produce telescoping and anchoring movements powered by vacuum pressure. The introduction of grooves to valley crease significantly lowersthe full contraction vacuum pressure and improves the response, allowing the system can be driven by an onboard micro vacuum pump, enabling the possibility of miniaturization, integration, and untethered operation of the robot.A series of crawling experiments in pipes with different sizes and cross sections constructed by acrylic are conducted to validate the crawling performance of the robot. Within square cross-section pipes, the robot can achieve a velocity of 9.4 mm/s in horizontal crawling and 7.7 mm/s in vertical upward crawling. For horizontal crawling in circular pipes, it can reach avelocity of 8.0 mm/s. When fully charged, the robot can crawl for 40 min with a mileage of 16.649 m, which is sufficient for most drainage and industrial pipelines detection tasks. The robot demonstrates excellent endurance and speed perfor-ma that excd mostistingtethered o piperawling robots.

Key words: Crawling robot')">Crawling robot, Soft-rigid hybrid actuator, Untethered, Origami actuator, Pipe detection