Modular Assembly: An Efficient Approach for Creation and - - PowerPoint PPT Presentation

Modular Assembly: An Efficient Approach for Creation and Maintenance of Persistent Space Assets

2019 IEEE International Conference on Robotics and Automation

William (Bill) R. Doggett Structural Mechanics and Concepts Branch NASA Langley Research Center, Hampton, Va. 23681 USA

Outline

2

• Definition of Persistent Asset and Motivation
• Persistent Asset: Benefits
• Past Assembly History and Why is Assembly Viable Now
• Design for Persistence Applied to Applications
• Large Precision Reflector
• Persistent Platform: Solar Electric Transfer Vehicle
• Langley Research Center (LaRC) Technology Development Efforts
• Concluding Remarks

Multiple Low Cost Launch Options: Dia. ~ 5 m

12 m 17 m 19.1 m

Need: New cross-cutting modular approach supporting a new Persistent Asset operational paradigm.

Definition and Motivation

Problem: Single launch paradigm is unsustainable.

• Inability to repair and upgrade results in:
• conservatism: on-orbit technology is decades behind state of the art, and
• increased cost and complexity: redundant systems with elaborate deployment.
• Single launch limits performance due to mass and volume constraints

Why Now? New Paradigm for “Persistent Assets” enabled by:

• Multiple, frequent, and inexpensive

commercial launch options.

• In-space robotic capabilities integrated

with commercial spacecraft providing frequent, inexpensive visits.

• Advances in electronics,

computational architectures, and software systems. Persistent Asset: Any space system that benefits from multiple visits.

3

Significant Benefits of Persistent Asset Paradigm

4

• Pay as you go: Put initial capability in place and expand/evolve capability over time.

Provides a rapid return on investment.

• Increased capability or reduced life cycle costs through ability to:
• Upgrade: replace key competitive subsystems leaving “utilities” in place
• Expand and Reconfigure: to rapidly adjust to customer needs
• Service: reducing the need for high reliability of the entire system
• Increased Competition: well defined interfaces allow variety of commercial

companies to provide solutions

• Significantly increased design freedom because:
• Minimum mass will no longer be the primary driver and increases to system mass

can be traded to reduce:

• mission cost (design, development, and fabrication),
• mission risk (increased structural margins, carry spares)
• test and validation time
• Launch volume and payload shroud dimensions are no longer primary drivers

because the system can be economically distributed among a variety of vehicles

• More efficient launch packaging schemes can be used that minimize the impact of

launch loads.

• The total spacecraft can thus be designed and optimized for in-service

(zero-g) loads as opposed to launch loads which are the current primary driver.

1985 1988

Maintenance and Repair

1992

What is Different from Past Assembly Approaches?

Space Station Freedom

2015

LEO EVA International Space Station Assembly (1998-2011) and Servicing(1998-)

1985

• Early work focused on structure, not system
• Space Station relied heavily on astronaut support

5

Robotic Approaches are Viable for Assembly and Servicing

DARPA/Space Systems Loral RSGS Northrop Grumman MEV 1995 NASA Restore L 2008 Japanese Kibo module positioned Automated Structures Assembly Laboratory Custom Tools Feedback from Environment

• Supervised Robotics are viable for space operations
• Multiple robotic vehicles and providers entering market
• Increasing need for cost effective rapid refresh of systems
• Telecommunications
• Space and Earth Science
• Space Exploration

Persistent Asset Paradigm

New Operational Paradigm Needed

6

Persistent Asset Application: Large Precision Reflector

7

• Astrophysics and space science community desires >

20-meter diameter aperture for next space telescope.

• Persistent asset paradigm currently being applied to
• vercome single-launch limitations.
• Telescope structural modules and connectors

currently being developed at LaRC.

Hedgepeth 1984 Vaughan 1981 Thronson 2014

LaRC Technology Development: Tri-Truss Modular Architecture

Mirror Close Out Structural Member (1 of 3) Core Bottom Members Top Members Central Triangle

Tri-Truss significant features

• No repeated members at interfaces
• Statically Determinate Structure
• Packages efficiently
• Statically Stable Structure through

deployment

• High performance Assembled Structure
• Variety of locations to attach operational

sub-systems Tri Truss Module Deployed Packaged

8

Ortho-View Side View

9

Multi-Nut Captive Bolt

LaRC Technology Development: Modular Telescope Metallic Connection for Assembly Tests

2-meter Prototype Hardware

10

Persistent Asset Application: Persistent Platform Group

Key Interfaces: Module: Backbone Truss Component: Instrument Geo Platform Solar Electric Propulsion Tug Earth Science Station DARPA GEO Platform Fuel/Servicing Depot

Test Platform Packaged for Launch

+

Assembled and Deployed

Connection Deployed for clarity Prepared for assembly

11

Pla lay V Vid ideo https://youtu.be/FK8gD5PY-Ng

Large-Scale Zero-G Application (1): Persistent Platform Solar Electric Transport Vehicle (SETV)

• SETV conceived as having a

modular system architecture.

• Modular architecture allows for SETV

to expand capability over time enabling increased payload capability, reduced trip time and negates solar array efficiency limitations.

• Modules developed have broad

applicability to other systems such as:

• Science platforms,
• Power beaming platforms,
• Communications platforms.
• Structural modules and modular

connectors being developed at LaRC

12

LaRC Technology Development: Persistent Platform

13 Keel Truss Structure Solar Tug Module Assembly Direction Alignment Guide (Removable) Non-Structural Supports (Removable) Capture Spring Pins New Module Existing Spacecraft Long Reach Manipulator Precision Positioner Calibration Block Joint Response

2-meter Prototype Hardware

Concluding Remarks

14

• Space operations are on the cusp of a revolutionary new operational

paradigm that is enabled by new space robotic capabilities and frequent, low-cost launch opportunities.

• Key attributes and benefits of a new “Persistent Asset” operational

paradigm that leverages these new capabilities has been introduced.

• Application of the Persistent Asset Paradigm to two relevant space systems

were described.

• The active development of modular technology at LaRC supporting

implementation of Persistent Assets was summarized. Adoption and application of the Persistent Asset Paradigm can begin immediately

Backup

15

Node and Connecting Joints Erectable Structures: Space trusses are comprised of strut members connected at nodes

• Efficient packaging
• Structurally simple and predictable

Space Shuttle (54 m, [184 ft]) 36 Strut Members 36 struts 12 node clusters 1976

Historical In-Space Assembly: Unique Packaging Opportunities

16

Predictability Key to Acceptance

• Truss structure surface accuracy of 50-100 microns (~0.002-0.004”)
• Center-fed parabolic reflector design with 3 fold symmetry
• Primary support truss 45 nodes 150 graphite epoxy struts

4m-Diameter

• Aprior Predictions
• No tuning

1995

MAC (modal assurance criteria, 1 = perfect match

Historical In-Space Assembly: Robotic Assembly

Background: Past Assembly Projects (Agent: Robot) Objective: Reliable predictable precision assembly of multiple structural forms from common components.

8m [26 feet] diameter 20m [66 feet] linear beam Strut Installation Tool Panel Installation Tool 1995

Panel Utilities – Mixed Modules with Power Strip

Utilities at the corners and sides 4 4 4 4 4 4 4 4 4 Moveable power strip

Videos of Referenced Work

RAMSES video https://youtu.be/FK8gD5PY-Ng Automated Structures Assembly Lab (ASAL) https://www.youtube.com/watch?v=h6-U_XINL8k&feature=youtu.be Precision Trusses https://www.youtube.com/watch?v=SBvOv5zJvJ4&feature=youtu.be Telerobotic Advances https://www.youtube.com/watch?v=4oS2BANNAlM&feature=youtu.be