Soft Spherical Tensegrity Robot Design Using Rod-Centered Actuation and Control

Abstract

This paper presents the design, analysis and testing of a fully actuated modular spherical tensegrity robot for co-robotic and space exploration applications. Robots built from tensegrity structures (composed of pure tensile and compression elements) have many potential benefits including high robustness through redundancy, many degrees of freedom in movement and flexible design. However to fully take advantage of these properties a significant fraction of the tensile elements should be active, leading to a potential increase in complexity, messy cable and power routing systems and increased design difficulty. Here we describe an elegant solution to a fully actuated tensegrity robot: The TT-3 (version 3) tensegrity robot, developed at UC Berkeley, in collaboration with NASA Ames, is a lightweight, low cost, modular, and rapidly prototyped spherical tensegrity robot. This robot is based on a ball-shaped six-bar tensegrity structure and features a unique modular rod-centered distributed actuation and control architecture. This paper presents the novel mechanism design, architecture and simulations of TT-3, the first untethered, fully actuated cable-driven six-bar tensegrity spherical robot ever built and tested for mobility. Furthermore, this paper discusses the controls and preliminary testing performed to observe the system’s behavior and performance.

Fluid-driven origami-inspired artificial muscles

“…These muscles can be easily made from a large variety of materials, and they are able to generate powerful, efficient, and programmable multidimensional actuation. This technique allows us to quickly program, fabricate, and implement actuation systems for very specific working environments at multiple scales, such as active metamaterials ( 44 ), miniature surgical devices ( 45 , 46 ), wearable robotic exoskeletons ( 47 ), transformable architecture, as well as deep-sea manipulation ( 48 ) and large deployable structures for space exploration ( 49 , 50 ). The use of negative pressure offers a safer way of actuation for FOAMs compared with artificial muscles driven by highly pressurized fluids.…”

Inclined surface locomotion strategies for spherical tensegrity robots

“…In this paper, the neutral stance of the robot refers to the stance in which no cables are contracted and the only tension in the system is due to gravity. While other robots have successfully achieved punctuated rolling on flat ground using this technique [16], [15], we show that the TT-4 mini is not only capable of the same, but can also do so on an inclined surface. This section summarizes the results for a single-cable actuation policy and sets the standards against which we evaluate the improved climbing capabilities achieved through two-cable actuation (Section V).…”

A Soft Robot for Random Exploration of Terrestrial Environments

“…Tensegrity structures are self-stabilized three-dimensional networks composed of two components: the struts, working only in compression and the cables, working only in tension [19]. This feature allows a tensegrity structure to withstand mechanical shocks and be lightweight at the same time [14][19] [20]. Both features are beneficial for building a protective cage for jumping robots.…”