Built On-Orbit Robotically assembled Gigatruss (BORG)

Virginia Tech Spring 2021 - Present

Full BORG Truss Assembly

BORG Exploded View

To facilitate further exploration of space and off-world bodies, structures exceeding current payload fairing must be constructed so methods of In-Space Servicing, Assembly, and Manufacturing (ISAM) are being explored. However with their strut-by strut assemblies, space trusses are incredibly complex with a very high number of components. But they do reduce the risk of single point failures found in complex deployablement methods needed to fit large constructions into payload fairing.

The following showcases our methodology of leveraging a mixed assembly architecture to take advantage of both fewer components and modularity. This mixed assembly scheme features deployable and close out elements are staggered in an alternating checkerboard pattern. This pattern can be extended to any odd nxnxn size, shown here at a 3x3x3 scale

Three Mixed Assembly Modules

This mixed assembly method utilizes three types of modules to create the 3x3x3 BORG structure: (1) 9 deployable trusses, (2) 6 close-out-squares, and (3) 12 close-out-struts. The deployable has flexible, pre-tensioned cross diagonals made of metal cabling. The deployable is designed with corner nodes that include a one way bearing to allow it to fully deploy but not back drive.

Architecture Validation Trade Study

Chapin, S.*, Everson, H.*, Chapin, W., Quartaro, A., and Komendera, E. (2023). Built On-orbit Robotically Assembled

Gigatruss (Borg): A Mixed Assembly Architecture Trade Study. Frontiers in Robotics and AI, 10.

https://doi.org/10.3389/frobt.2023.1109131

BORG Robots

The robotic manipulators utilized in this experimentation Lightweight Surface Manipulation System (LSMS), originally developed at NASA Langley Research Center. LSMS is used for gross manipulation such as deployment and placing of modules. These operations are aided by a dexterous manipulator, the Jigging Apparatus for Closeout Structures (JACS), an end effector Stewart platform (SP) robot used to help with precise adjustments to refine deployment and placement of modules. In addition, JACS has an onboard camera for local metrology.

Lightweigth Surface Manipulation System (LSMS)

Jigging Apparatus for Closeout Structures (JACS)

Hardware Construction

These test truss modules were manufactured and assembled in the FASER Lab. The corner nodes, deployable mid-nodes, strut ends, and close-out-square corners were 3D printed with PLA filament. The deployable corner nodes had the internal components for deployment pre-inserted before the node was clamped inside a concave custom clamp while the epoxy cured. The flexible diagonal components were comprised of two flexible sections per side with a turnbuckle placed in the middle. The connections to both the turnbuckle and inner node components were facilitated by a small crimpled loop of cable. This was ideal for separating the top and bottom planes of the deployable, overcoming any small measurement inconsistencies, and fine-tuning the pre-tensioning values. A jig was constructed to ensure the flexible diagonal lengths were consistent to create the desired pre-tension.

BORG Demonstration

The demonstration required four kinds of tasks to take place

Full extension of deployable unit
Placing a locked out deployable unit
Inserting a close out strut
Inserting a close out panel

The underlined tasks were able to be robotically completed while at this stage insertions are done manually.

Demonstration Media

Personal Contribution

Within this project I was aided in the physical creation and assembly of the BORG nodes, flexible diagonals, deployable units, close out elements. I also helped in designing the standoffs for the turn table and the deployment site. I was also responsible for the creation of the JACS components.

In addition. I also physically created all the metrology tags on the BORG as well as created the objects for them in the Optitrack program.

All test was conducted as a team and so elements of demonstration prep and management were also accomplished by me as well.

During the validation trade study paper my work covered the launch vehicle analysis, packing analysis, scalability, and time to competition research.

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