When Rolling Gets Weird: A Curved-Link Tensegrity Robot for Non-Intuitive Behavior

TL;DR

This paper introduces a semi-circular curved-link tensegrity robot that balances efficient rolling and stability, demonstrating non-intuitive behaviors through simulations and experiments, with potential for space exploration applications.

Contribution

The work presents a novel curved-link tensegrity robot design and a dynamic model, expanding understanding of non-traditional rolling behaviors and control in tensegrity systems.

Findings

Successful experimental validation of non-intuitive rolling behaviors

Demonstrated shock absorption and conformability of the structure

Simulations reveal new insights into positional displacement during locomotion

Abstract

Conventional mobile tensegrity robots constructed with straight links offer mobility at the cost of locomotion speed. While spherical robots provide highly effective rolling behavior, they often lack the stability required for navigating unstructured terrain common in many space exploration environments. This research presents a solution with a semi-circular, curved-link tensegrity robot that strikes a balance between efficient rolling locomotion and controlled stability, enabled by discontinuities present at the arc endpoints. Building upon an existing geometric static modeling framework [1], this work presents the system design of an improved Tensegrity eXploratory Robot 2 (TeXploR2). Internal shifting masses instantaneously roll along each curved-link, dynamically altering the two points of contact with the ground plane. Simulations of quasistatic, piecewise continuous locomotion sequences reveal new insights into the positional displacement between inertial and body frames. Non-intuitive rolling behaviors are identified and experimentally validated using a tetherless prototype, demonstrating successful dynamic locomotion. A preliminary impact test highlights the tensegrity structure's inherent shock absorption capabilities and conformability. Future work will focus on finalizing a dynamic model that is experimentally validated with extended testing in real-world environments as well as further refinement of the prototype to incorporate additional curved-links and subsequent ground contact points for increased controllability.