Self-Propelled Ink Deposition Robot (SPIDR) that 3D Prints Structures in Space
Abstract
We propose spider-inspired 3D-printing robots, called Self-Propelled Ink Deposition Robots (i.e., SPIDRs), that fabricate complex large structures in space by crawling on the web-like constituent struts that they simultaneously print. The inherent flexibility underlying the fabrication approach of these SPIDRs will enable structures of almost any geometry to be made in space for satisfying the requirement of numerous applications and for addressing a variety of unanticipated scenarios on demand (e.g., repairing structures damaged by space debris). Additionally, since the structures that the SPIDRs fabricate consist of ink that is pumped to their deposition nozzles through tethers connected to storage containers, only the ink needs to be periodically launched into space to replenish the containers once the SPIDRs have already been deployed there. Thus, all required building materials can be brought into space in their most compact, volume-efficient, and shape-flexible form for dramatically reducing the cost of space structures. The automated and swarm-inspired teamwork that SPIDRs leverage would also increase the fabrication speed of such structures, which would reduce their cost further. Although there are numerous challenges that need to be addressed to enable the proposed robots, the most important and thus the one that this effort will most directly address is the challenge of enabling vibration compensation. It is difficult to 3D print structures with sufficient feature resolution when the nozzle depositing the ink is continually vibrating different and unanticipated amounts in all six degrees of freedom (i.e., three independent translations and three independent rotations) with respect to the structure being printed. Such vibrations are inevitable since the SPIDRs crawl on the structures while their geometry changes as they are printed and as temperatures fluctuate cyclically as the structures orbit. Other sources of vibrations include tidal gravitational forces or gravitational forces from other orbiting bodies. Moreover, natural frequency vibrations will be passively induced within the large printed structures since they are largely undamped in the vacuum of space. The legs of the SPIDR, which anchor the print nozzle to the structures being printed are also relatively compliant by necessity and consist of multiple actuators arranged in serial configurations that will give rise to other vibrations. Thus, we aim to design a print head with large-deformation flexures that can be actuated with sufficient speed and precision to correct for the print head’s vibrations such that its nozzle can remain stable with respect to the structure that it is printing. Moreover, new approaches will be explored for enabling the sensing of the relative nozzle locations with respect to its printed structure such that closed-loop control can be employed.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 01, 2020
- Source ID
- HR00112010002
Entities
People
- Jonathan B. Hopkins
Organizations
- Defense Advanced Research Projects Agency
- University of California, Los Angeles