AI-generated conceptual illustration created locally with Exas. This imagined pipe robot illustrates the subject; its appearance is not an exact depiction of the SPPIRO research prototype.

The inside of a pipe can be a difficult place for a machine: a narrow passage may turn sharply, change width or branch into another direction. Researchers at the University of Michigan have built SPPIRO, an untethered soft robot that approaches those obstacles with a movement inspired by earthworms. The university described the research on 9 June 2026. [1]

Anchor, stretch and move

The robot uses anchoring modules at its ends and a flexible central body. Holding one end against the pipe wall gives the middle section something to push or pull against. Its folded pneumatic actuators extend and contract, helping the machine move and steer through confined spaces. [1]

The research paper, published in npj Robotics on 1 June, reports tests in pipes between 140 and 200 millimetres across, including vertical sections, right-angle bends and T-junctions. Power, sensing and control are carried onboard, so a trailing tether is not needed for the demonstrated operation. [2]

Feeling the route from inside

SPPIRO also uses its own changing shape as information. Measurements from the actuators help estimate the body’s configuration and the geometry around it. Soft contact sensors help establish whether the anchors are touching the wall. In an enclosed pipe, those signals offer information that an observer outside cannot simply see. [2]

A useful prototype, with work ahead

The university report identifies limits that still need attention. The soft body can sag in horizontal sections, and frequent contact with a wall can reduce mapping accuracy. The researchers are exploring a stiffer torso and an additional body segment. These are engineering challenges for future development, rather than evidence of a finished inspection service. [1]

The appeal of the design is its change of viewpoint. Instead of treating flexibility only as a weakness, it uses controlled deformation as part of locomotion and sensing. For readers interested in nature and machines, it is a concrete example of a biological movement inspiring an engineered tool—without the robot being a living worm.

Sources & further reading

Prepared with AI assistance and checked against the university report and research paper linked above. The source publication dates are distinct from this article’s publication date.