ELIS ResLab member participates in NASA research project

The Intelligent Robotics Group at the NASA Ames Research Center in Mountain View, California is studying actuated Tensegrity structures for planetary exploration. The goal is to build a robotic system that is capable of handling EDL (Entry, Descent, and Landing) scenarios as well as mobility once the probe has landed on the surface. While the Tensegrity robot as a whole will be for EDL and mobility, a payload with science equipment will be suspended within the middle of the structure. 

As part of this research effort, Ken Caluwaerts spent 7 months at the NASA Ames Research Center to work on the development of a new robot, nicknamed SUPERball (Spherical Underactuated Planetary Exploration Robot). The design of this robot is to a great extent inspired by a prototype developed at the Reservoir Lab. This untethered prototype robot nicknamed ReCTeR (left in the Figure) can roll and actively fold and deploy and has a mass of only 1.1kg including batteries and actuators. 

Tensegrity (tensile-integrity) is a design principle based on the concept of embedding compressive members (struts/bars) in a tension net (springs/cables). Using this technique, it is possible to design freestanding "jointless" structures in which compressive members do not directly connect. Each tensile or compressive element is only subject to axial loading, which allows for efficient use of materials. In serial manipulators forces tend to accumulate at the joints, while they dissipate through the whole structure in a Tensegrity robot, resulting in increased robustness. 

A Tensegrity mission can have a high mass fraction between science payload and overall weight (as measured at atmospheric entry) due to its ability to perform EDL and mobility. This will enable cheaper and new forms of surface exploration that utilize their natural tolerance to impacts. Titan (Saturn's largest moon) is the main project focus, because its low gravity and dense atmosphere would allow for atmospheric entry and landing of a Tensegrity probe without parachutes or retrograde rockets. Physical drop tests and simulations have shown that a Tensegrity structure can protect a suspended payload during impact.

SUPERball is the new modular robot under development at NASA Ames, which incorporates many of ReCTeR's design aspects. It is a more robust robot with powerful actuators and more advanced sensory equipment. The Figure shows a SUPERball strut on the right. The new robot has a diameter of 1.5m for a total mass of approximately 12kg. The increased size and actuation power allows for future research into payload protection and transportation.  

The project is funded by the NASA Innovative Advanced Concepts program, which sponsors research into new technology that could dramatically impact how NASA develops and conducts its missions. Out of more than 600 white papers originally submitted, this proposal is one out of only 18 that were funded for 2012 as a NIAC phase 1 project. In August 2013, NIAC renewed its support for the Tensegrity project with funding for an additional two years. Other project collaborators are Case Western Reserve University, the University of California Berkeley, the University of California Santa Cruz, the University of California San Diego, Oregon State University, the University of Idaho and the Ecole Polytechnique Fédérale de Lausanne.

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