Skip to content

RUBIC: An Untethered Soft Robot with Discrete Path Following

Research output: Contribution to journalArticle

Original languageEnglish
Article number52
Number of pages11
JournalFrontiers in Robotics and AI
DateAccepted/In press - 24 Jun 2019
DatePublished (current) - 12 Jul 2019


Soft robots have the potential to diminish the need for humans to venture into unsuitable environments or work in extreme conditions. While their soft nature gives them the advantage of being adaptable to changing environments, their control can be challenging because of the compliance that makes them effective. In this paper we present RUBIC: the Rolling, Untethered, Ballooning, Intelligent Cube, that overcomes some of the difficulties of 2D control by constraining motion to a discretised Cartesian space. RUBIC's method of locomotion is by rolling from one face of the cube to another, in any one of four directions. This motion causes it to move within a 2D grid structure, the dimensions of which are defined by the cube's characteristic length. When in its resting position RUBIC is inherently stable and forms a safe platform for tasks including taking measurements and soil samples, for localisation and adhoc network infrastructure, and as the foundation for larger robots and structures. We present the design of RUBIC's body, the four pneumatic ballooning actuators per face that generate its unique gait, and the control systems for locomotion and obstacle climbing. We consider constraints imposed by the design and fabrication methods including physical dimension and weight, material properties and control fidelity. An alternative locomotion scheme is proposed to improve the speed and linearity which also increases the distance travelled per roll. RUBIC travels with a mean locomotion accuracy of 4.58 degrees deviation and successfully traverses steps up to 35% of its own height. The discretisation of a soft robotics workspace, as demonstrated by RUBIC, has advantages for safe and predictable locomotion and has applications in both structured and hazardous environments.

    Structured keywords

  • Tactile Action Perception

    Research areas

  • RoboSoft Grand Challenge, Robosoft, fluidic elastomer actuators, Untethered, Locomotion, soft robotics

Download statistics

No data available



  • Full-text PDF (final published version)

    Rights statement: This is the final published version of the article (version of record). It first appeared online via Frontiers Media at . Please refer to any applicable terms of use of the publisher.

    Final published version, 1 MB, PDF document

    Licence: CC BY


View research connections

Related faculties, schools or groups