Tech Briefs

Robustness Analysis and Robust Design of Uncertain Systems

Langley Research Center, Hampton, Virginia A methodology was developed for the analysis and design of systems subject to parametric uncertainty in which design requirements are specified via hard inequality constraints. Hard constraints are those that must be satisfied for all parameter realizations within a given uncertainty model. Uncertainty models are given by norm-bounded perturbations from a nominal parameter value (i.e., hyperspheres) and by sets of independently bounded uncertain variables (i.e., hyperrectangles). These models, which are also quite practical, allow for a rigorous mathematical treatment within the proposed framework. Hardconstraint feasibility is determined by sizing the largest uncertainty set for which the design requirements are satisfied.

Posted in: Briefs, Electronics & Computers, Software

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XDB3 Extension for Equality and Relational Operators

Ames Research Center, Moffett Field, California While keyword full-text searches work well for textual data, they do not work well for numeric, date, or other more highly structured information. In particular, Netmark/XDB could retrieve any record where the author contained “Knight” in the text, but could not return only those records from Calendar Year 2010 that have “Knight” in their author section. Traditional relational databases allow for rich comparison “relational” operators; for example, one can express a query such as “return all rows where the signature date is on January 1, 2010.” Netmark/XDB, being primarily targeted at XML processing and retrieving XML-structured data, was designed for full-text querying to find keywords. Most other XML indexing and querying systems also are designed with the assumption that content (“CDATA”) is textual or binary data that can be queried against, but not with relational comparison operators like “greater than a value.”

Posted in: Briefs, Electronics & Computers, Software

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Simulator for a Self-Stabilizing Synchronization Protocol for Arbitrary Digraphs

Langley Research Center, Hampton, Virginia This work was conducted to create a means of simulating and visualizing the behavior of a self-stabilizing distributed clock synchronization protocol developed at LaRC (Langley Research Center). The protocol has many applications including projects that directly pertain to work being done at NASA. Time synchronization is a critical component of many projects, from computer networking and distributed systems, to autonomous flight. This easy-to-understand interface both displays accurate information concerning the protocol, and conveys its utility.

Posted in: Briefs, Electronics & Computers, Software

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Testing Encapsulation of Internet, DTN, and LTP Traffic over AOS Space Data Link Protocol

NASA’s Jet Propulsion Laboratory, Pasadena, California The CCSDS ENCAP Over AOS Over UDP software engine encapsulates live Internet Protocol (IP), DTN Bundle Protocol (BP), or Licklider Transport Protocol (LTP) traffic over a Consultative Committee for Space Data Systems (CCSDS)-compliant Encapsulation Ser vice (ENCAP) running over an Advanced Orbiting Systems (AOS) data link protocol UDP stream. Many space missions currently use the AOS protocol, and this software is an implementation of a standard mechanism to encapsulate Internet Protocol traffic (including interactive Web applications and streaming video) and DTN Bundle Protocol traffic (for large file transfers over high latency links) over ENCAP over AOS.

Posted in: Briefs, Electronics & Computers, Software

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Multifunctional Ablative Thermal Protection System

This material has applications in aerospace systems, manufacturing, and structural components requiring three-dimensional reinforcement. Ames Research Center, Moffett Field, California The Orion crew module highlighting the compression pads in the heat shield. NASA has developed a unique and robust multifunctional material called 3-Dimensional Multifunctional Ablative (3DMAT) Thermal Protection System (TPS) that meets both the structural and thermal performance needs for a lunar return mission and beyond. 3DMAT uses a game-changing woven technology tailored to the needs of the Orion Multi-Purpose Crew Vehicle (MPCV) compression pad. Compression pads serve as the interface between the crew module and service module of the Orion MPCV. The compression pads must carry the structural loads generated during launch, space operations, and pyroshock separation of the two modules. They must also serve as an ablative TPS withstanding the high heating of Earth re-entry. 3DMAT leverages NASA’s investment in woven TPS to design, manufacture, test, and demonstrate a prototype material for the Orion compression pads that combines the weaving of quartz yarns with resin transfer molding.

Posted in: Briefs, Materials

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Limboid Reconfigurable Robots for In-Space Assembly

A Limboid workforce with access to a tool crib could staff robotic space factories. NASA’s Jet Propulsion Laboratory, Pasadena, California 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.

Posted in: Briefs, Machinery & Automation, Robotics

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Cam Hand

This robust gripper design has applicability to both robots and as a prosthetic for the physically challenged. NASA’s Jet Propulsion Laboratory, Pasadena, California A durable gripper tool was designed for use by RoboSimian robots intended for use in disaster scenarios that demand high-force, robust manipulation. The resulting Cam Hand fills a previously unaddressed niche that emphasizes grip strength and robustness over dexterity. The design uses a number of unique features to ensure high operational flexibility. While this gripper was created for use on a robot, its basic design could be refined for other applications; in particular, as a new class of prosthetic that would exist between the traditional hook and pinch models and the dexterous models currently under development.

Posted in: Briefs, Machinery & Automation, Robotics

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