Geometric Estimation of the Deformation and the Design Method for Developing Helical Bundled-Tube Locomotive Devices

This paper presents a novel design method for an in-pipe locomotive device named “helical bundled-tube locomotive device.” Helical bundled-tube locomotive devices are soft robots that travel in pipes. The device only comprises inflatable tubes; it deforms into a helical shape and travels in a pipe with pneumatic power. The deformation pushes the device toward the inner wall of the pipe and generates a traction force in the pipe. Therefore, the extent of deformation should be determined. The methods for estimation and estimation-based design, which this paper presents, allow for the device to be designed without employing trial-and-error experimentation; trial-and-error experimentation is ordinarily required. The proposed methods are quick and easy to implement, and will help in putting the device to practical use. The proposed methods are based on geometrical formulations of the deformations of the device and the tubes that compose the device. This geometrical formulation is independent of the mechanical characteristics of the material. We also considered the developed design method as being independent from the tube characteristics to simplify it. Accordingly, the proposed methods can be applied regardless of material, shape, and individual differences across helical devices.