Figure 1. A laboratory prototype of a Limbi robot autonomously builds a modular structure. This process could repeat to build a large truss or spacecraft. As shown here, the modules are small, but a similar approach would work for large modules.

Many future space vehicles, planetary bases, and mining operations will be too large and heavy to launch on a single rocket. Instead, component parts would need to be launched on multiple rockets and assembled in space. To enable versatile in-space assembly, a novel class of reconfigurable robots called Limboids has been conceptualized. Limboids are robotic limbs that attach and detach from each other to form a variety of useful configurations. These configurations might be as small as a single limb, which is best for dexterous manipulation of small parts, or as large as necessary for gross manipulation. As a modular system, Limboids could be supplemented with additional tools and limbs.

A core concept of Limboids is “modularity at the limb scale.” Each robot, called Limbi, is a self-mobile limb and can function as a standalone robot for single-handed tasks. For example, one Limbi could grab a battery pack from a storage container and insert it into a satellite. Both ends of Limbi are electromechanical docks that can attach to a structure, other robots, or tools like grippers and drills. The base structure powers and controls the robots through these docks, so Limbi can walk end-over-end across the structure without a battery or tether. Researchers recently used a prototype Limbi to demonstrate end-over-end mobility and assembly of a modular structure (Figure 1).

Figure 2. Limbi robots can form a wide variety of Limboid configurations, enabling small-scale dexterous manipulation, gross manipulation of large objects, docking with incoming spacecraft, and two-handed manipulation.

Because the electromechanical docks provide power to the robots, Limboids could move around and reconfigure themselves without the complexity of power cords. Examples of configurations and use cases for Limboids are shown in Figure 2. These configurations consist of a) Limbi robots working in parallel to perform independent or cooperative work, b) a long arm for grabbing incoming spacecraft, c) a walker-manipulator to carry objects while moving, and d) a torso with multiple arms for manipulating large objects. The use cases include e) three limbs working together to build a chain of parts, and f) a two-armed Limboid holding a large object.

In the future, Limboids might help build a large orbiting structure, such as a solar farm or an asteroid-processing facility. They could unpack structural components and climb out along the structure as they build it, using built-in power lines instead of carrying tethers or batteries. Alternatively, they might staff an orbiting spacecraft factory, where they would crawl around on trusses or walk on a floor. There, they would grab incoming shipments, unpack spacecraft components, assemble a solar panel array, and attach tanks, batteries, and instruments to the spacecraft hull. They could be embedded in either of these settings and meet manipulation demands over many years of factory use and multiple spacecraft design cycles.

This work was done by Sawyer Brooks, Peter T. Godart, Brendan Chamberlain-Simon, Russell G. Smith, and Paul G. Backes of Caltech for NASA’s Jet Propulsion Laboratory. NASA is seeking partners to further develop this technology through joint cooperative research and development. For more information about this technology and to explore opportunities, please contact Dan Broderick at This email address is being protected from spambots. You need JavaScript enabled to view it.. NPO-50052

NASA Tech Briefs Magazine

This article first appeared in the June, 2016 issue of NASA Tech Briefs Magazine.

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