A Single Chamber Minibot With Elastic Hinges for Adapting Various Diameter Pipelines

Abstract

Adopting smart materials and structures for locomotion could minimize the body size of pipeline robots, thereby enhancing their coverage, especially in long-distance and small-diameter regions. Pneumatic pipeline robots and electric active ones show good potential, still they suffer challenges in long-distance travel due to increased system damping, and adaptation to a large diameter ratio due to insufficient active deformation, respectively. In this article, we developed a single chamber minibot that integrates a dielectric elastomer as the vibration source and pneumatic hinges for the elastic support of bristles. The active pressurized chamber serves as: an antagonism in the axial direction to provide actuation stability for DE resonance, and elastic hinges in the radial direction to support and regulate the bristles. A contact force analysis indicates that the elastic hinges play a significant role in adapting to various diameter pipelines by reducing the normal contact force compared to the traditional bending of flexible bristles. A finite element model is developed to optimize the structural design and analyze the mechanisms of contour variation by regulating the initial angle of bristles and chamber stiffness. The primary prototype demonstrates rapid locomotion, achieving more than 0.4 body length per second in vertical pipelines with inner diameters of 12–16 mm (diameter ratio of 1.33), satisfying the critical value of 1.26 in a typical parent-twin pipeline as predicted by Murray’s Law. The compact structure offers advancements for locomotion in long and small pipelines with various diameters, presenting new opportunities for the miniature design of pipeline robots.