Technology Focus

Electronics/Computers

Software

Materials

Mechanics/Machinery

Manufacturing

Bio-Medical

Physical Sciences

Information Sciences

Books and Reports

02-14 February 2014

NASA Tech Briefs, February 2014 1

INTRODUCTION

Tech Briefs are short announcements of innovations originating from research and development

activities of the National Aeronautics and Space Administration. They emphasize information considered likely to be transferable across industrial, regional, or disciplinary lines and are issued to

encourage commercial application.

Additional Information on NASA Tech Briefs and TSPs

Additional information announced herein may be obtained from the NASA Technical Reports Server:

http://ntrs.nasa.gov.

Please reference the control numbers appearing at the end of each Tech Brief. Information on NASA’s

Innovative Partnerships Program (IPP), its documents, and services is available on the World Wide Web

at http://www.ipp.nasa.gov.

Innovative Partnerships Offices are located at NASA field centers to provide technology-transfer access to

industrial users. Inquiries can be made by contacting NASA field centers listed below.

Ames Research Center

David Morse

(650) 604-4724

david.r.morse@nasa.gov

Dryden Flight Research Center

Ron Young

(661) 276-3741

ronald.m.young@nasa.gov

Glenn Research Center

Kimberly A. Dalgleish-Miller

(216) 433-8047

kimberly.a.dalgleish@nasa.gov

Goddard Space Flight Center

Nona Cheeks

(301) 286-5810

nona.k.cheeks@nasa.gov

Jet Propulsion Laboratory

Dan Broderick

(818) 354-1314

daniel.f.broderick@jpl.nasa.gov

Johnson Space Center

John E. James

(281) 483-3809

john.e.james@nasa.gov

Kennedy Space Center

David R. Makufka

(321) 867-6227

david.r.makufka@nasa.gov

Langley Research Center

Michelle Ferebee

(757) 864-5617

michelle.t.ferebee@nasa.gov

Marshall Space Flight Center

Terry L. Taylor

(256) 544-5916

terry.taylor@nasa.gov

Stennis Space Center

Ramona Travis

(228) 688-3832

ramona.e.travis@ssc.nasa.gov

NASA Headquarters

Daniel Lockney,

Technology Transfer Program Executive

(202) 358-2037

daniel.p.lockney@nasa.gov

Small Business Innovation Research

(SBIR) & Small Business Technology

Transfer (STTR) Programs

Rich Leshner, Program Executive

(202) 358-4920

rleshner@nasa.gov

NASA Field Centers and Program Offices

5 Technology Focus:

Test & Measurement

5 JWST Integrated Simulation and Test (JIST) Core

5 Software for Non-Contact Measurement of an

Individual’s Heart Rate Using a Common Camera

6 Rapid Infrared Pixel Grating Response Testbed

6 Temperature Measurement and Stabilization in a

Birefringent Whispering Gallery Resonator

7 JWST IV&V Simulation and Test (JIST) Solid State

Recorder (SSR) Simulator

9 Manufacturing & Prototyping

9 Development of a Precision Thermal Doubler

for Deep Space

9 Improving Friction Stir Welds Using Laser Peening

10 Methodology of Evaluating Margins of Safety in

Critical Brazed Joints

11 Electronics/Computers

11 Interactive Inventory Monitoring

11 Sensor for Spatial Detection of Single-Event Effects

in Semiconductor-Based Electronics

12 Reworked CCGA-624 Interconnect Package

Reliability for Extreme Thermal Environments

13 Current-Controlled Output Driver for Directly

Coupled Loads

15 Materials & Coatings

15 Bulk Metallic Glasses and Matrix Composites as

Spacecraft Shielding

16 Touch Temperature Coating for Electrical

Equipment on Spacecraft

16 Li-Ion Electrolytes Containing Flame-Retardant

Additives

19 Mechanics/Machinery

19 Autonomous Robotic Manipulation (ARM)

21 Software

21 CARVE Log

21 Platform Perspective Toolkit

21 Convex Hull-Based Plume and Anomaly Detection

21 Pre-Filtration of GOSAT Data Using Only Level 1

Data and an Intelligent Filter to Remove Low Clouds

21 Affordability Comparison Tool — ACT

22 “Ascent — Commemorating Shuttle” for iPad

22 Cassini Mission App

22 Light-Weight Workflow Engine:

A Server for Executing Generic Workflows

22 Model for System Engineering of the

CheMin Instrument

25 Information Technology

25 Timeline Central Concepts

25 Parallel Particle Filter Toolkit

26 Particle Filter Simulation and Analysis Enabling

Non-Traditional Navigation

26 Quasi-Terminator Orbits for Mapping Small

Primitive Bodies

27 The Subgrid-Scale Scalar Variance Under Supercritical

Pressure Conditions

27 Sliding Gait for ATHLETE Mobility

28 Automated Generation of Adaptive Filter Using a

Genetic Algorithm and Cyclic Rule Reduction

NASA Tech Briefs, February 2014 3

This document was prepared under the sponsorship of the National Aeronautics and Space Administration. Neither the United States Government nor any person acting on behalf of the United States Government assumes any liability resulting from the use of the information contained

in this document, or warrants that such use will be free from privately owned rights.

02-14 February 2014

NASA Tech Briefs, February 2014 5

Technology Focus: Test & Measurement

JWST Integrated Simulation and Test (JIST) Core

Modeling techniques and hardware models have potential commercial applications for projects

that deploy similar solutions.

Goddard Space Flight Center, Greenbelt, Maryland

The James Webb Space Telescope

(JWST) Integrated Simulation and Test

(JIST) environment is a software-only

system simulator that provides an environment to exercise JWST flight software subsystems and interfaces. JIST is

capable of executing the unmodified

flight software binaries in an operational environment that can be configured on a single personal computer.

JIST utilizes the JWST ground system,

ground system command and telemetry

databases, simulated flight computers,

instrument simulators, and environment simulators. Some of the capabilities provided by JIST include the ability

to load and run any version of the flight

software, inject errors (faults) from

ground system test procedures, save simulation state (processor and simulators), and simulate external hardware

devices. Many components are potentially reusable on future missions. In addition, the modeling techniques and

models have potential commercial applications for projects that deploy similar hardware solutions.

The IV&V Program does not have a

means to exercise the JWST flight software subsystems in a repeatable and consistent fashion, and the IV&V Program

does not have sufficient budget to set up

a hardware-in-the-loop test environment.

JIST provides a mechanism to set up a

test environment for the IV&V Program

to dynamically validate flight software behaviors and examine unexpected flight

software behaviors (independent tests).

JIST also has the potential to provide a

means to validate new test procedures

prior to executing on hardware-in-theloop environments, decrease procedure

development time, and provide a ground

operations training platform.

JIST provides a cost-effective means

for the IV&V Program to perform dynamic analysis on software systems; provides a test framework for mission operations teams; provides a cutting-edge test

environment with accompanying tools;

and makes testing embedded flight software test environments more accessible

and convenient for users and testers.

JIST can be configured to execute on

a single personal computer, and can test

hardware faults in nominal and offnominal conditions. It can save and reload test scenarios at any point during a

test, integrate easily with commercial

debuggers, utilize unmodified flight binaries, and not require hardware acquisition or maintenance.

This work was done by Brandon Bailey,

Justin Morris and Mark Pitts of Goddard Space

Flight Center; Daniel Nawrocki of Athena Sciences; Steven Seeger of MPL; Justin McCarty

and Scott Zemerick of Galaxy Global Corporation; Jeffery Joltes and Tim Riley of Allegheny

Science & Technology Corporation; and

Charles Rogers of Embedded Flight Systems,

Inc. Further information is contained in a

TSP (see page 1). GSC-16739-1

Software for Non-Contact Measurement of an Individual’s

Heart Rate Using a Common Camera

John H. Glenn Research Center, Cleveland, Ohio

A software application detects the

heart rate of an individual by using a

real-time video stream from a common camera connected to their computer. This involves no contact between the user and the camera, or

calibration between individual users.

NASA’s OpenMDAO framework was

used to implement and coordinate the

necessary data acquisition and signal

processing functions.

The software finds the location of the

user’s face within an incoming stream of

images from a connected camera, and

then isolates the forehead region. Data

is collected from this location for a segment of time to estimate the user’s heart

rate by measuring average optical intensity in the forehead location, in the

subimage’s green channel alone.

A bandpass filter designed to isolate

and magnify spectral components between 0.8 Hz and 3 Hz is computed

on the gathered optical intensity data.

With good lighting and minimal noise

due to motion, a stable heartbeat is

isolated in about 15 seconds. Accuracy has been tested against commercial heart rate monitors used for

sports medicine.

Once the user’s heart rate has been estimated, real-time phase variation associated with this frequency is also computed. This allows for the heartbeat to

be exaggerated in the post-process

frame rendering, causing the highlighted forehead location to pulse in

sync with the user’s own heartbeat.

This work was done by Tristan Hearn of

Glenn Research Center. The application was developed at NASA Glenn Research Center in support of OpenMDAO, under the Aeronautical

Sciences Project in NASA’s Fundamental Aeronautics Program, as well as the Crew State Monitoring Element of the Vehicle Systems Safety

Technologies Project, in NASA’s Aviation Safety

Program. Further information is contained in

a TSP (see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed to

NASA Glenn Research Center, Innovative

Partnerships Office, Attn: Steven Fedor, Mail

Stop 4–8, 21000 Brookpark Road, Cleveland,

Ohio 44135. Refer to LEW-19090-1
6 NASA Tech Briefs, February 2014

Rapid Infrared Pixel Grating Response Testbed

NASA’s Jet Propulsion Laboratory, Pasadena, California

A test array has been developed to

measure the response of pixel-integrated infrared gratings over a wavelength range from 3 to 13 μm for multiple grating geometries. This array allows

for testing and for determining the performance of an infrared focal plane

array camera before resources have

been committed to the design and fabrication of the final array.

The 320×256 array of 25-μm test pixels

comprises five types of grating geometries

with theoretical peak response varying in

0.25-μm steps from 3 to 13 μm. The array

has been designed to be hybridized to a

FLIR-Indigo 9705 read out integrated circuit (ROIC). On the same lithographic

mask as this array, large-area (200 μm) pixels have been designed with the same grating parameter sweep. Together the small

and large area pixel comprise the rapid infrared pixel grating response testbed. This

testbed pattern is typically fabricated on

one of JPL’s long wavelength infrared

(LWIR) quantum well infrared photodetector (QWIP) wafers. The 320×256 detector array is then bonded to the FLIR/Indigo 320×256 ROIC, and used as the

electronic backbone of the testbed. The

array is then thinned to replicate the characteristics of a standard deliverable camera array. Response of the test pixels is

then measured and compared to the expected response. Shifts due to cavity and

lithographic fidelity effects can be compensated for, and the final imaging array

design can be made with confidence.

This work was done by Cory J. Hill, Jason

M. Mumolo, and Daniel W. Wilson of Caltech for NASA’s Jet Propulsion Laboratory.

Further information is contained in a TSP

(see page 1). NPO-47823

Whispering gallery mode (WGM) resonators have been suggested for use as

reference cavities for laser stabilization.

Because of their unique properties

(small size, high stability, narrow line

width), such application appears to

hold great promise. It is expected to

allow for the exceptionally high optical

frequency stability.

The main practical difficulty associated with using WGM resonators for

laser stabilization arises from the fundamental fact that the light propagates inside an optical material. This appears to

be a disadvantage compared with low-expansion Fabry-Perot resonators that are

essentially vacuum-filled. In WGM resonators, the material’s optical properties

set the limit not only for the resonator’s

Q-factor, but also for its stability.

The most important factors contributing to variation of the WGM resonance

frequency are the thermal refractivity

and thermal expansion. These variations

can be suppressed if the resonator temperature is stabilized to the micro-Kelvin

level. To achieve this, the temperature

dependence of the resonator’s own

anisotropy is used.

Temperature dependence of the resonator anisotropy leads to a temperature-dependent frequency difference

between the TE and TM mode families.

This frequency difference can be measured with a high precision, and the temperature variations are extracted. These

variations are then suppressed by two

digital control loops.

The first practical implementation of

the dual-mode stabilization approach has

been achieved, and active temperature

stabilization of a WGM resonator at above

room temperature has been demonstrated. Temperature stabilization at the

level of 200 nK was achieved when integrated for one second, and below 10 nK

when integrated for 10,000 seconds. This

considerably surpasses state-of-the-art

temperature sensors; especially temperaTemperature Measurement and Stabilization in a Birefringent

Whispering Gallery Resonator

Applications include optical clocks, spectroscopy, and optical transponders.

NASA’s Jet Propulsion Laboratory, Pasadena, California

The experimental setup of the WGM Resonator. Temperature of the brass cube in the photo is set to 76 oC

and is stabilized to a few hundred nanodegrees using the dual-mode stabilization technique. (Note: EOM

is electro-optic modulator, WGMR is whispering gallery mode resonator, T ctrl. is temperature control, DAQ

is data acquisition, and PBS is polarizing beam splitter.)

EOM

Laser

DAQ

Freq. Sweep

T ctrl.

WGMR

Opt. Power Ctrl.

Polarization Ctrl.

PBS

Photodetectors
NASA Tech Briefs, February 2014 7

JWST IV&V Simulation and Test (JIST) Solid State Recorder

(SSR) Simulator

Dynamic analysis capabilities are provided with no hardware in the loop.

Goddard Space Flight Center, Greenbelt, Maryland

As described in “JWST Integrated Simulation and Test (JIST) Core” (GSC16739-1) on page 25, the JIST system is a

software-based simulator that uses the

James Webb Space Telescope (JWST) operational ground system, ground system

command/telemetry databases, simulated flight computers, and unmodified

flight software binaries to provide dynamic analysis capabilities. There is no

hardware in the loop; the flight software

communicates over a simulated MILSTD-1553 and Spacewire port. The JIST

SSR Simulator is a reusable component

of the JIST system, and is responsible for

simulating basic SSR functionality.

In order to develop a software-only

test environment for the JWST mission,

a solution was needed to simulate the

behaviors of the JWST SSR. The as-is solution requires the utilization of an Excalibur 1002 Single Board Computer

running custom software to simulate

SSR functions and interfaces to the

JWST Command and Telemetry Processor (CTP).

The JIST SSR Simulator is a component of the JIST system and is responsible for simulating basic SSR functionality. The primary purpose of the SSR

Simulator is to assist in performing independent verification and validation

(IV&V) of the flight software. The SSR

simulator is a software-only simulator

that provides the necessary interface to

the JWST flight software and typically

simulates SSR management functions.

Specific functions include playback,

record, and telemetry transmission.

The SSR simulator is also equipped

with many different configurations that

can be initialized using command line

arguments.

The JIST SSR simulator is softwareonly and eliminates the need to acquire

and maintain various hardware equivalent configurations. The simulator provides additional functionality and configurations to support specific independent

testing objectives.

This work was done by Scott Zemerick of Goddard Space Flight Center. Further information

is contained in a TSP (see page 1). GSC16741-1

ture control techniques. This result is significant not only in the context of laser

stabilization, but also as a demonstration

of a novel temperature sensor with a

broad spectrum of potential applications.

A WGM-based temperature sensor

with nano-Kelvin sensitivity operating at

room temperature was demonstrated. It

was used to stabilize a WGM resonator at

the level of a few nano-Kelvin, which will

allow use as an ultra-stable laser lock reference. The demonstrated technique

can be used in a variety of other applications requiring high temperature stability, as well as ultra-sensitive measurements of temperature variations. These

include thermal stabilization of a quartz

oscillator, mid- or far-IR sensitive

bolometers, precise calorimetric measurements in chemistry, and study of optical and mechanical aging effects in various crystalline resonators.

This work was done by Dmitry V. Strekalov,

Nan Yu, Robert J. Thompson, and Ivan S.

Grudinin of Caltech for NASA’s Jet Propulsion

Laboratory. Further information is contained

in a TSP (see page 1). NPO-48222

NASA Tech Briefs, February 2014 9

Development of a Precision Thermal Doubler for Deep Space

A copper thermal doubler is used to spread the thermal loads.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Thermal requirements and a need for

a very flat mechanical interface led to

the development of a copper doubler

for the titanium vault on the Juno Spacecraft. The vault is designed to contain

the science instruments on the spacecraft, protecting them from damage due

to the extreme radiation environment of

Jupiter. The titanium used in the vault

creates unwanted thermal effects due to

the poor thermal conductivity of titanium. To remove heat from the telecommunication equipment mounted to the

interior of the vault, a copper thermal

doubler was used to spread the thermal

loads over the entire area of the radiator

(located on the outside of the vault),

which decreased the effective thermal

resistance through the vault wall. A

method of bonding a copper doubler to

the titanium preserves the mounting interface flatness to less than 0.005 in.

(0.13 mm) while providing a superior

thermal path to the radiators, which are

fitted with thermal control louvers. The

precisely controlled titanium surface,

and that of the milled copper doubler

with integral spacing features, provides

the mechanical interface flatness, structural integrity, and thermal performance required by the telecommunications subsystem.

Utilizing precision milling techniques, a copper doubler was milled

down to 0.065 in. (1.7 mm) to within

±0.001 in. (0.03 mm). Then, the panel

was undercut by 0.005 in. (0.13 mm) in

all areas except where fasteners were

placed. Around each fastener a boss was

provided for good thermal conduction

along with the maintenance of precision

spacing of the component mounting

surface. Bosses were also added in areas

where no fasteners were needed to preserve the spacing between the copper

and titanium. Precision milling of the

part was chosen after blanchard grinding failed due to warping and galling of

the copper. The copper thickness was

such that a special vacuum fixture with

liquid cooling was required. Weep holes

were added to the bosses to allow for the

excess bonding material to exit and not

be trapped under the panel (which may

lead to flatness issues). Finally, the entire

panel was bonded to the titanium using

a precision 5-mil bond line established

by the stand-off structures milled into

the doubler.

This technique will result in a precision surface for the attachment of critical hardware that requires such a flat

mounting surface, and provides the advantage of a mechanical thermal path at

the bolted interfaces (a dry interface)

while also proving a thermal interstitial

material to fill all other voids (a wet interface) between the thermal doubler

and the titanium panel. When properly

prepared (including a primer), the RTV

affords a bonded joint strength of approximately 500 psi (3.5 MPa) to provide structural integrity for the mounting of other parts.

This work was done by Kelley E. A. Alwood, Phillip A. Yates, Jerry J. Gutierrez, Gerald S. Gaughen, Bradley W. Kinter, Christopher C. Porter, and Terry Bennett of Caltech

for NASA’s Jet Propulsion Laboratory. Further

information is contained in a TSP (see page

1). NPO-47296

Manufacturing & Prototyping

Improving Friction Stir Welds Using Laser Peening

This technique can be used in any application of friction stir welding, including automotive,

railroad, and maritime industries.

Lyndon B. Johnson Space Center, Houston, Texas

Friction stir welding (FSW) has

emerged as a promising solid-state

process with encouraging results, particularly when used on high-strength aerospace aluminum alloys that are generally difficult to weld. Laser peening has

been applied to friction stir welds in

order to improve the mechanical and fatigue properties of welded joints. Laser

peening introduces a compressive residual stress at the surface that can extend

several millimeters or deeper into the

material. These residual stresses resulting from laser peening can be significantly higher and deeper than for conventional shot peening, resulting in

superior mechanical and fatigue properties in FSW.

An increasing number of applications are using FSW to join materials

that were not considered weldable

using conventional fusion welding

methods. However, the rigid clamping

configuration required to clamp the

parts during the FSW process, along

with the heating cycle the material experiences during welding, can result in

high residual stresses in the weld.

These residual stresses, along with the

reduction in properties from the welding process, are likely to affect the mechanical and fatigue properties and

therefore influence the in-service performance of structural components.

The weld strength in some cases can be

improved by post-weld heat treatment.

However, this is not always an option in

welded structural components. Consequently, laser peening was investigated

as a means for improving the mechanical and fatigue properties in FSW.

For the laser peening process, different peening layers were used in an effort

to identify the optimum number of

peening layers capable of producing superior properties. The laser peening

process was applied over the desired

treatment area in a raster fashion.
10 NASA Tech Briefs, February 2014

The laser-peened samples displayed an

approximate increase of 60 percent to

the yield strength of the material. Conventional shot peening exhibited only a

slight improvement to the tensile properties when compared to the unpeened

FSW specimens. A subsequent investigation also revealed that laser peening resulted in a reduction in the grain size on

the surface of the processed part, which

may also explain some of the increase in

tensile properties. However, the increase

in mechanical properties from the laser

peening was mainly attributed to the

strain hardening, which can be explained by the generation of dislocations

under the effect of the plastic deformation from the high energy laser peening.

The resulting increase in dislocations

tends to increase the flow resistance of

the material to plastic deformation.

After the laser peening was applied,

tensile residual stresses introduced

during the welding process were found

to become compressive. In general, the

crack growth behavior in friction stir

welded coupons is a function of microstructure, residual stresses, and

specimen geometry. The results in this

study indicate a significant reduction

in fatigue crack growth rates using

laser peening compared to the native

welded specimens. This reduced fatigue crack growth rate was comparable

to the base unwelded material. In contrast, shot peened specimens did not

result in a significant reduction to fatigue crack growth.

Significant hardness improvement

was achieved by processing the FSW

2195 aluminum alloy samples with laser

peening. The laser-peened samples

processed using six layers exhibited a

hardness increase of around 28 percent

on the top surface, and a 21-percent increase on the bottom side of the weld

nugget region. The hardness levels due

to laser peening increased proportionally with the number of peening layers.

Corrosion behavior of laser peened

FSW samples was investigated by submerging several specimens (some laser

peened and some unpeened) in a

sodium chloride solution for 60 days.

After comparing the samples, it was noticed that the corrosion pits size and

number were large on the unpeened

surfaces, whereas they were much

smaller on the laser treated surface.

This work was done by Omar Hatamleh of

Johnson Space Center. Further information is

contained in a TSP (see page 1). MSC24551-1

Methodology of Evaluating Margins of Safety in Critical

Brazed Joints

Goddard Space Flight Center, Greenbelt, Maryland

This methodology provides a guide

consisting of design, testing, and structural analysis steps developed to assure

positive strength margins of safety (MS)

in critical brazed joints used for assembly of flight and non-flight structures.

This effort was promoted by concerns

expressed by industry and NASA engineers and program management that

the current practices of assuring positive

MS in structural brazed joints vary widely

among the centers, NASA contractors,

and manufacturers, making the verification of structural adequacy difficult in

cases involving multiple centers, other

government agencies, and their suppliers. A lack of uniform methodology of

estimating MS of the brazed joints leads

to increasing cost of verification structural integrity of the critical hardware

fabricated by brazing.

The methodology is based on testing

standard butt- and lap-brazed test specimens to establish shear and tensile allowables, developing failure criterion in the

form of interaction equations consisting of

the stress ratios, and verifying this failure

criterion by testing realistic or geometryspecific test specimens representing the

actual structure on a sub-component level.

The novelty of this methodology is

that it is the first time that interactive

equations were applied to the brazed

joints. The methodology was verified on

AlBeMet 162/AWS BAlSi-4, CRES

304/AWS Bag-8, Ti-6Al-4V/AWS Bag-8,

Ticuni and Ti-6Al-4V/Al 1100 base

metal/filler metal combinations.

This work was done by Yury Flom of Goddard Space Flight Center. Further information is contained in a TSP (see page 1). GSC16042-1
NASA Tech Briefs, February 2014 11

Electronics/Computers

Interactive Inventory Monitoring

This system queries the location and status of an item in an inventory. Ames Research Center, Moffett Field, California

The invention is a radio frequency identity detector (RFID)-based system that assists a user in location of an item, in response to an electronic query for the

status of the item. The item(s) being

sought may be a book on a library shelf, an

item from a store inventory, a legal or financial document, a medical record, a

weapon system or weapon component

(presumably) located in an armory, or

similar item.

Each item is tagged by an RFID, which

does not require a battery, but is preferably powered using an electromagnetic

coil that is embedded in, or associated

with, the item. The shelving, or other

container, provides an alternating electromagnetic field to power the embedded coils, and can identify the item location if the item is on, or adjacent to, the

shelving/container, even if the item is

not in its assigned location. Each coil includes a low-power, programmable chip

containing relevant information on the

item (ID number, class to which the item

belongs, present status of the item, relevant item characteristics, recent activity

affecting the item, etc.). Removal of the

item from the shelf/container may first

require entry of specified information,

including but not limited to user name,

user contact information, user priority

level (if applicable), date the item was

removed, and user authentication information. An associated light emitting

diode (LED) array containing different

colored LED light sources is optionally

included for visual indication of location(s) of the item.

A desired item is specified and/or categorized using a database system with a

computer interface. The interface may

be a portable interrogator wireless electronic unit that communicates with the

database, and with the item(s) sought.

When the portable interrogator unit

queries an RFID tag, the computer interface downloads information on the item

from the database, and/or from the

shelving/container (e.g. availability

and/or recent location and/or present

status of the item). Optionally, based

upon a color code scheme assigned to

the particular handheld unit, the shelving/container LED array displays the corresponding distinguishable color scheme

wherever the item(s) is/are located.

This system can also provide security

for an inventory of weapon systems,

weapon components, and biological/

mechanical warfare substances or other

sensitive items that require extreme

protection. In this instance, the inventory receptacle is powered continuously,

and each protected item emits a unique,

encrypted code associated with the

item, when the item is on, in, or adjacent to the receptacle at its assigned location. When the protected item is not

on or adjacent to the receptacle at its assigned location, or is located elsewhere

on or adjacent to the receptacle, an

alarm or notification signal is issued by

the system, indicating when the item

was last sensed at its assigned location.

Use of an encrypted code of appropriate complexity can minimize or eliminate the possibility of “spoofing” to

cover absence of the protected item.

Entry of an encrypted password allowing access to the protected item could

be used to avoid prompt issuance of an

alarm signal.

This work was done by Stevan M. Spremo

and Usen E. Udoh of Ames Research Center.

Further information is contained in a TSP

(see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed

to the Ames Technology Partnerships Division

at 1-855-NASA-BIZ (1-855-6272-249) or

sumedha.garud@nasa.gov. Refer to ARC15684-1.

Sensor for Spatial Detection of Single-Event Effects in

Semiconductor-Based Electronics

The positional ionizing radiation sensor detects energy levels that cause faults in electronic circuits.

Marshall Space Flight Center, Alabama

Ionizing radiation has a detrimental

effect on digital electronics that need to

operate in extraterrestrial environments. As space missions become longer

and more complex, there is a need for

flight computers that can withstand

harsh radiation environments while delivering the increased computation and

power efficiency required by future missions. Field-programmable gate arrays

(FPGAs) are becoming an attractive

platform for flight computers due to

their inherent flexibility through inflight reprogrammability. FPGAs promise to deliver reconfigurable computing

platforms that can dynamically alter

hardware architectures to address the

current application demand. While

FPGAs are attractive from a performance perspective, they can be especially

susceptible to single-event effects

caused by ionizing radiation. In addition to traditional circuit faults caused

by radiation, FPGAs are prone to faults

in their configuration memory. These

faults can physically alter the hardware,

leading to failures that cannot be recovered from using traditional fault mitigation techniques.

A sensor was designed to detect the

spatial location of radiation strikes of energy levels that can cause faults in commercial FPGA substrates. A tile-based
12 NASA Tech Briefs, February 2014

During the past two decades, large,

high-density, high-input/output (I/O)

electronic interconnect SMT (surface

mount technology) packages such as

ceramic column grid arrays (CCGAs)

have increased usage in avionics hardware of NASA projects. The test boards

built with CCGA packages are expensive and often require rework to replace

reflowed, reprogrammed, failed, or redesigned CCGA packages. Theoretically, a good rework process should

have a similar temperature-time profile

as that used for the original manufacturing process of solder reflow. A multiple rework process may be implemented with CCGA packaging

technology to understand the effect of

the number of reworks on the reliability

of this technology for harsh, extreme,

thermal environments.

CCGA 624 packages have been increasing in use based on their advantages such as high interconnect density, very good thermal and electrical

performance, and compatibility with

standard surface-mount packaging assembly processes. Reworked CCGA

packages are used in space applications such as logics and microprocessor functions, telecommunications,

flight avionics, and payload electronic

assemblies. As these packages tend to

have less solder joint strain relief than

leaded packages, the reliability of reworked CCGA-624 packages is very

important for short- and long-term

space missions.

In general, reliability of the assembled electronic packages reduces as a

function of number of reworks, and the

extent of reliability loss is not known

yet. A CCGA rework process has been

implemented to design a daisy-chain

test board consisting of 624 packages.

Reworked CCGA interconnect electronic packages of printed wiring polyimide boards have been assembled and

inspected using non-destructive x-ray

imaging and optical microscope techniques. The assembled boards after first

rework were subjected to extreme temperature thermal atmospheric cycling

to assess their reliability for future

Reworked CCGA-624 Interconnect Package Reliability for

Extreme Thermal Environments

The effect of the number of reworks is examined on the reliability of this technology for harsh,

extreme thermal environments.

NASA’s Jet Propulsion Laboratory, Pasadena, California

computing architecture has been designed to take advantage of the sensor

information to spatially avoid regions

with potential faults, and then perform a

repair procedure in the background.

The sensor is integrated with the

many-tile computing system implemented on an FPGA to provide environmental information to the computer in

order to improve its fault tolerance. The

X-Y location of ionizing radiation strikes

is passed to the computer, and is used to

spatially avoid and repair potentially

faulted regions of the computer fabric.

There have been numerous sensor designs for monitoring position and energy

of radiation with variations in resolution

and system integration. The design selected utilizes double-sided strip detectors and silicon drift detectors for their

simple design, speed, and ease of production without sacrificing position and energy resolution. The principle of the strip

detector is based on a large area p-n

diode, very similar to a solar cell. The difference stems from the electrodes in the

radiation sensor, which are broken up

into narrow strips running orthogonal to

each other on both sides of the substrate,

each of them being read-out with a separate electronic channel. The location of

the ionizing radiation is given by the position of the intersection of the strips receiving the signals from the front.

This sensor is unique in that it detects

energy levels that are only capable of

causing faults in semiconductor-based

electronics. The use of the sensor to provide environmental information to a digital circuit so that the digital circuit can

preemptively mitigate a possible fault is

a novel use-model for a radiation sensor.

This work was done by Brock LaMeres and

Todd Kaiser of Montana State University for

Marshall Space Flight Center. For more information, contact Sammy Nabors, MSFC Commercialization Assistance Lead, at sammy.

a.nabors@nasa.gov. Refer to MFS-32975-1

CCGA 1272 after 1880 thermal cycles

Optical Photographs of the fatigued solder joints in a 1st Reworked CCGA 624 package after 1,026

thermal cycles of –185 to +125 °C.
NASA Tech Briefs, February 2014 13

Current-Controlled Output Driver for Directly Coupled Loads

This driver is relatively compact and less costly in reducing energy.

Lyndon B. Johnson Space Center, Houston, Texas

Driving loads such as electric motors,

relay coils, and solenoids requires a relatively large initial pull-in or start-up current from a driver in order to initiate operation of the load. To maintain

continuous operation, the hold or running operating current required for a

load may be 20% or less of the initial

pull-in or start-up current. The problem

is that a standard driver circuit acting as

a switch continues to provide the same

current throughout operation, wasting

energy, and must be large enough to

provide the large current continuously.

A new driver provides a smaller, less

costly method of reducing energy to

drive the load. It uses a transformerless

direct-coupled pulse width modulation

(PWM) switching driver to control the

current to the load. Circuit area is reduced by directly coupling the driver circuitry to the load, thus eliminating the

transformer, diodes, and output capacitors. This invention does not provide the

electrical isolation of the transformercoupled topology or as wide an input

voltage operational range. However,

many applications do not require isolation or the wide operating input voltage

range of the transformer-coupled

method. Therefore, they can benefit

from the reduced energy consumption

and circuit area of the direct-coupled

topology described here.

This innovation uses electronic components that are assembled and interconnected on a printed wiring board to

isolate the high and low side of a dual

bus input. The driver circuit uses a PWM

control topology with a series switching

element. The PWM provides control of

the output current by modulating the

switching duty-cycle. The current may

thus be controlled to any level desired

using any number of potential algorithms. For example, the current feedback to the PWM control circuitry may

be fed through a delay element that inhibits the current limiting for a period

of time required for proper pull-in or

start-up of the load. This provides two

distinct levels of load current: a large initial pull-in or start-up current followed

by the lower hold or running operating

current. This could also be accomplished by simply timing the turn-on and

switching between one or more control

points as desired.

This driver can maintain a consistent

level of isolation between independent

power inputs. No single failure within

the avionics electronics will cause independent power buses to lose electrical

isolation, and a simple diode O-ring cannot be used. These requirements apply

to both supply and return lines.

The innovation also addresses a highreliability problem of load control via

electronic circuit breaker (ECB). ECB

dynamic control can be implemented

via simple FPGA (field programmable

gate array) means.

This work was done by Nathan Moyer,

Thomas Bingel, Deanne Tran-Vo, George

Cebry, Paul Santrach, and Charles McCracken III of Honeywell for Johnson Space

Center. For further information, contact the

JSC Innovation Partnerships Office at (281)

483-3809.

Title to this invention has been waived

under the provisions of the National Aeronautics and Space Act {42 U.S.C. 2457(f)} to

Honeywell. Inquiries concerning licenses for its

commercial development should be addressed to:

Honeywell

P.O. Box 52199

Phoenix, AZ 85072-2199

Refer to MSC-24766-1/7-1/76-1/82-1, volume and number of this NASA Tech Briefs

issue, and the page number.

deep-space mission environments. The

resistance of daisy-chained interconnect sections was monitored continuously during thermal cycling to determine intermittent failures. This test

data shows a limitation of these reworked CCGA 624 packages for various

projects. This research has reported the

reliability study of CCGA 624 packages

down to –185 °C and up to +125 °C.

This work was done by Rajeshuni Ramesham of Caltech for NASA’s Jet Propulsion Laboratory. Further information is contained in a

TSP (see page 1). NPO-49083

NASA Tech Briefs, February 2014 15

Materials & Coatings

Bulk Metallic Glasses and Matrix Composites as

Spacecraft Shielding

These materials offer combinations of high hardness, low melting temperature, low density, and

formability like a plastic.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Spacecraft shielding is defined as the

outer layer of a satellite or spacecraft that

protects it against micrometeorite and

orbital debris (MMOD), radiation damage, and re-entry temperatures. There

are several problems with the design and

implementation of shields, particularly

in the area of MMOD shielding. Spacecraft and satellites need to have the lowest possible mass due to the enormous

cost per pound of putting them into

orbit or deep space. However, low Earth

orbit (LEO) is currently littered (and increasingly so) with orbital debris, primarily remnants of rocket upper stages,

satellites, and pieces of spacecraft that

have broken away or have collided with

other objects. The major threat is that

this debris is traveling at 8 to 18 km/s,

and any piece larger than a few centimeters has the kinetic energy to potentially

become a “spacecraft killer.” Large debris is tracked with radar, but the smaller

debris (below a centimeter or so) is too

small to track and must be mitigated by

shields in the event of a collision. The International Space Station, for example,

employs over 500 different shield designs

into its outer skin, which are designed to

protect a variety of vital components.

Designing new materials for MMOD

shielding is a compromise among ballistic performance, areal density, volume,

and geometry. Shields are often comprised of multiple materials stacked in

layers or as foams and function by vaporizing, diffusing, and catching a projectile

without compromising the inner wall of

the spacecraft. Materials that have been

used in shields include aluminum panels

and foams, titanium, carbon fiber,

Kevlar, and Nextel cloth, among others.

Aluminum is widely used both as panels

and as cellular structures due to its low

areal density and easy fabrication; however, aluminum is a soft metal with a low

ballistic limit compared with other metals (like titanium and steel, for example).

Empirical ballistic limit equations have

been developed for many potential

shield materials, which has lead to the

observation that their hardness is one of

the best indicators of shielding effectiveness. A new class of metal alloys, which

seems to have an optimal combination of

properties for MMOD shielding, are

bulk metallic glasses (BMGs, also called

amorphous metals) and their composite

derivatives. BMGs are metal alloys that

have been designed with chemical composition and high cooling rates such that

they freeze in an amorphous (non-crystalline) state. This gives them unique mechanical properties, including ultra-high

strength and hardness, low stiffness, density similar to titanium, and formability

like plastics. BMG matrix composites,

which are reinforced with soft, crystalline

phases that grow as dendrites, are alternative materials that exhibit the same

Sample Materials and Tests: (a) A four-layered bulk metallic glass matrix composite (BMGMC) cellular

structure fabricated by capacitively joining individual layers (shown in the inset). (b) A three layer test

panel of the BMGMC used for hypervelocity testing compared with (c) an aluminum honeycomb with

the same thickness. (d-g) Hypervelocity impacts of 3 mm aluminum projectiles at ≈3 km/s into a variety of BMG and BMGMC panels. (d) Impact into a single layer of the BMGMC shown in (a). (e) Impact

into a thin BMGMC panel with the same thickness as in (d). It is noted how the egg-box structure diffuses the debris versus the flat panel. (f) Impact into the panel in (b) showing no penetration. (g) Impact into a 4-layer BMG Whipple shield showing no penetration. (h) Example of the test panel used

in (f). (i) Long exposures of the impacts in (d-g) where the light intensity indicates the energy absorbed

during impact (the red line is the triggering light for the camera).
16 NASA Tech Briefs, February 2014

In order to improve the safety and

performance of lithium-ion cells, especially over a wide operating temperature range, a number of Li-ion electrolytes have been developed that

contain flame-retardant additives in

conjunction with fluorinated co-solvents to provide a safe, wide-operatingtemperature-range system. Previously,

fluorinated esters were incorporated

into multi-component electrolyte formulations and their performances

have been demonstrated over a wide

temperature range (–60 to +60 °C).

The fluorinated esters co-solvents were

employed due to their favorable properties and improved safety characteristics, mainly associated with their low

Li-Ion Electrolytes Containing Flame-Retardant Additives

Battery improvements for portable electronics and electric vehicle applications can be realized.

NASA’s Jet Propulsion Laboratory, Pasadena, California

beneficial mechanical properties as the

monolithic BMGs, but with the added

benefits of ultra-high fracture toughness

and ductility, making them suitable for

high-performance structural applications. Particularly, BMGs have high hardness (6 times harder than Al alloys), relatively low density (twice as dense as Al

alloys), and low melting temperatures

(the same as Al alloys), which makes

them effective at vaporizing incoming

debris while assuring that the part of the

shield that is impacted also melts or vaporizes, preventing solid debris from hitting the spacecraft wall.

Over the last two years, JPL, in collaboration with Johnson Space Center and

the University of Southern California,

have been performing the first hypervelocity impact tests on BMGs and their

composites, with promising results.

Thin, corrugated panels of BMG composites, which have been formed into

multi-layered cellular structures through

capacitive joining, have shown to be extremely effective at mitigating impacts

from Al projectiles (see the figure). In

recent work, metallic glass sheets were

substituted for Kevlar in shields designed for the International Space Station and tested one-to-one against conventional shields at impacts up to 7

km/s. The new shields outperformed

the heritage ones in the preliminary testing. Since BMGs and their composites

can be formed into large sheets and panels with unmatched mechanical properties, they are potentially optimal materials for integration into future spacecraft

and satellites.

This work was done by Douglas C. Hofmann of Caltech for NASA’s Jet Propulsion

Laboratory. For more information, contact

iaoffice@jpl.nasa.gov. NPO-48402

Touch Temperature Coating for Electrical Equipment

on Spacecraft

Coating significantly increases the allowable touch temperature.

Lyndon B. Johnson Space Center, Houston, Texas

A coating has been developed that

can be applied to spacecraft equipment

to significantly increase the allowable

touch temperature limit, while only marginally degrading the heat transfer to

the environment.

The requirements for the coating are

to:

1. Limit skin temperature levels below

the pain threshold by:

a. Having low thermal mass.

b. Providing a resistance to heat flow

when the object is handled.

2. Cause minimal degradation to nominal on-orbit heat transfer.

These requirements were met in a

prototype by fabricating a layup consisting of, from top to bottom:

• A 0.004 in. (0.1 mm) thick aluminum

outer layer,

• A 0.0023 in. (0.06 mm) thick high-temperature acrylic transfer adhesive,

• A 0.002 in. (0.05 mm) thick square

stainless steel fin with longitudinal

waves that add crush strength,

• A second layer of transfer adhesive,

and

• A second aluminum facesheet.

The two aluminum facesheets act as

the outer heat transfer layer and the

layer that bonds to the equipment. The

facesheets are identical for convenience,

but are sized by the requirements for the

outer heat transfer layer.

In the crew cabin of a spacecraft, the

heat transfer is a combination of convection to the free-stream air and radiation to

the cabin walls. Because of the lack of buoyancy-driven natural convection and the low

cabin airflow, the convective heat transfer

coefficients are much lower than are normally found in terrestrial applications.

A mathematical heat transfer model

showed that the coating dramatically improves the allowable object temperature

for a given contact time — a 20 °F (11

°C) increase for long times and as much

as a 100 °F (56 °C) increase for short

times. The coating also improves the allowable time of contact for a given temperature. A bare 140 °F (60 °C) aluminum item can be held for 2.5 seconds

without pain, but with the coating, it can

be held for more than 2 minutes before

pain is felt.

The coating could be used in terrestrial applications where similar requirements exist: surface coatings that allow

ungloved handling of hot surfaces but

minimally impede nominal heat transfer.

For example, hot surfaces of powered

equipment that must provide cooling,

but can be inadvertently touched or handled during maintenance could be

coated for safety.

This work was done by Eugene K. Ungar

and Timothy K. Brady of Johnson Space Center. Further information is contained in a

TSP (see page 1). MSC-24726-1
NASA Tech Briefs, February 2014 17

flammability associated with their halogenated nature.

In the present work, the safety characteristics of these electrolytes have

been further improved by the addition

of flame-retardant additives, such as

triphenyl phosphate (TPP), tributyl

phosphate (TBP), triethyl phosphate

(TEP), and bis(2,2,2—trifluoroethyl)

methyl phosphonate (BTFEMP). A

number of electrolytes based upon

these approaches have delivered good

performance over a wide temperature,

good cycle-life characteristics, and improved safety characteristics; namely,

reduced flammability. Thus, the following electrolyte formulations were

investigated and demonstrated in experimental MCMB carbonLiNi0.8Co0.2O2 cells:

1. 1.0 M LiPF6 in EC+EMC+TFEB+TPP

(20:55:20:5 v/v %)

2. 1.0 M LiPF6 in EC+EMC+TFEB+TBP

(20:55:20:5 v/v %)

3. 1.0 M LiPF6 in EC+EMC+TFEB+TEP

(20:55:20:5 v/v %)

4. 1.0 M LiPF6 in EC+EMC+TFEB+BTFEMP (20:55:20:5 v/v %)

5. 1.0 M LiPF6 in EC+EMC+TPP (20:75:5

v/v %)

6. 1.0 M LiPF6 in EC+EMC+TPP (20:75:5

v/v %) + 1.5% VC

7. 1.0 M LiPF6 in EC+EMC (20:80 v/v%)

+ 1.5% VC

8. 1.0 M LiPF6 in EC+EMC (20:80 v/v%)

(baseline)

Of the electrolytes studied, 1.0 M

LiPF6 EC+EMC+TFEB+TPP (20:55:20:5

v/v%) (where TPP = triphenyl phosphate) was identified as being a promising non-flammable electrolyte, due to

reasonable low-temperature performance and superior life characteristics.

In addition, the electrolyte consisting

of 1.0 M LiPF6 EC+EMC+TPP (20:75:5

v/v%) + 1.5% VC was demonstrated to

have even further improved life characteristics due to the incorporation of a

solid electrolyte interphase (SEI) promoter (i.e., VC = vinylene carbonate),

which appears to inhibit the decomposition of the TPP.

A number of experimental Li-ion

cells, consisting of MCMB carbon anodes and LiNi0.8Co0.2O2 cathodes, have

been fabricated to study the described

technology. These cells serve to verify

and demonstrate the reversibility, lowtemperature performance, and electrochemical characterization techniques.

All cells displayed good reversibility at

room temperature and minimal reactivity during the formation cycling. The

high coulombic efficiency and comparable irreversible capacity losses are indirectly related to the overall stability of

the solutions and the electrode filming

characteristics. Reasonable reversibility

was observed with the cells containing

all the electrolyte variations, when compared after the formation cycling.

Some variation in capacity was due to

different electrode weights, and not to

electrolyte type, so most comparisons

were expressed in terms of percentage

of initial capacity under ambient temperatures. Triphenyl phosphate displayed the lowest irreversibility capacity

losses and the highest coulombic efficiency, suggesting that it is not electrochemically decomposing and participating in the electrode filming process

deleteriously.

This work was done by Marshall C. Smart,

Kiah A. Smith, and Ratnakumar V. Bugga

of Caltech and Surya G. Prakash of the University of Southern California for NASA’s Jet

Propulsion Laboratory. Further information

is contained in a TSP (see page 1).

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for its

commercial use should be addressed to:

Innovative Technology Assets Management

JPL

Mail Stop 202-233

4800 Oak Grove Drive

Pasadena, CA 91109-8099

E-mail: iaoffice@jpl.nasa.gov

Refer to NPO-46262, volume and number

of this NASA Tech Briefs issue, and the

page number.

NASA Tech Briefs, February 2014 19

Mechanics/Machinery

Autonomous Robotic Manipulation (ARM)

This sensor-driven, model-based approach can be applied to small-batch manufacturing

processes and explosive ordnance disposal.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Autonomous robotic manipulators

have the potential to increase manufacturing efficiency, provide in-home care,

and reduce the risk to humans in hazardous situations. The current challenge in autonomous robotic manipulation is to approach the capabilities of

dedicated, one-off manipulators in

known environments with versatile, inexpensive, and ubiquitous manipulator

systems that can operate in a range of

environments with only high-level

human input.

A sensor-driven, model-based approach continually uses environmental

interactions to update the system state,

and then uses these state estimates for

planning and control.

Instead of using the traditional senseplan-act paradigm for planning and

control execution of a robot, this innovation uses continuous estimation of the

entire system state to update and then

pre-plan actions, which are also deliberately executed, thereby increasing system state knowledge. This is done not

only for a specific task, but is done

across all tasks.

In general, the autonomy approach

presented here conforms to standard

system decompostions: Objects and the

environment are first segmented, classified, and localized using vision. Based

on the system state and models of the

environment, optimal grasp sets, manipulation strategies, and collision-free motion paths can be computed. As environmental interaction occurs, more sensors

such as tactile, force, and strain sensors

can be fused with visual sensing to provide updates of system state. Real-time

execution of task objectives, using feedback from sensors and state estimation,

drives system actuators. For all tasks, including drilling, unlocking, opening,

actuating, and grasping of various objects, a single strategy is used. Two diverse examples of picking up a screwdriver and unlocking a door are

described in this general manipulation

framework:

1. Non-Contact Perception, in which

only visual sensors are used to segment, classify, and localize objects in

the scene, and determine their pose

relative to environmental constraints

(such as a table or wall/door plane).

2. Approach, where using the initial system state estimates, optimal arm,

neck, and finger trajectories are

planned to bring the manipulator

near the object in a manipulatable

configuration. In the case of the

screwdriver on the table, the grasp set

will include a caging grasp, where

widely spaced fingers and the table

prevent object escape. For key insertion, the hand is brought near the

door handle.

3. Initial Contact/Relocation, where the

manipulator is in the same field of

view as the relevant objects, and estimation of the arm position (arm

tracking) allows the control to provide more precise relative hand-to-object motions. For all tasks, a general

contact strategy, where parts of the

manipulator are moved into contact

with the environment, is used to provide further relative localization.

4. Grasping or Manipulation, where

once sufficient relative object localization has been achieved, controlled execution of the primary specified task

objective (drilling, grasping, compression, actuation, etc.) is conducted.

This work was done by Nicolas H. Hudson, Thomas M. Howard, Paul G. Backes,

Abhinandan Jain, Max Bajracharya, Jeremy

C. Ma, Joel W. Burdick, Paul Hebert, and

Thomas F. Allen of Caltech for NASA’s Jet

Propulsion Laboratory. For more information,

contact iaoffice@jpl.nasa.gov. NPO-48095

The ARM Robot is depicted picking up a screwdriver.

NASA Tech Briefs, February 2014 21

Software

CARVE Log

This software reduces the workload

of the mission manager by distributing

selected aircraft data to the various investigators onboard the aircraft so they

do not have to continuously request the

data updates. This system will then send

the investigator’s comments and observations that were previously written in

notebooks to a server that archives

them in a file for later reference.

CARVE log is a system consisting of a

server and an Apple iPad app. The iPad

app displays aircraft attitude, location,

and other selected data to the user, and

allows the user to type in comments that

are tagged with the user’s initials and

sent to the server over wireless Internet.

The server receives the comments

from the app and stores them in a text

file on the disk, appending to it the most

recent aircraft location and attitude information. This appended information

serves as a time stamp for the comments

and observations. The data acquisition

programs also send the names, start, and

stop times of their data files to the

server, tagged with their instrument

identifier, removing the need to log

manually this critical information.

This work was done by Steven J. Dinardo,

Seth L. Chazanoff, and Charles E. Miller of

Caltech for NASA’s Jet Propulsion Laboratory.

For more information, contact iaoffice@

jpl.nasa.gov.

This software is available for commercial licensing. Please contact Dan Broderick at

Daniel.F.Broderick@jpl.nasa.gov. Refer to

NPO-48397.

Platform Perspective

Toolkit

This software specializes in discovering the location and intrinsic parameters of an imaging camera when such information was not recorded in the

metadata of an image. It provides a simple command line interface for specifying the input and output for the two

camera perspectives.

Using the Get_Platform_Perspective.m

function, for a given image, it discovers

the position and intrinsic parameters of

the camera that took the image. Points in

the scene must be correlated to points in

real space, typically represented in latitude, longitude, and altitude.

Using the Apply_Platform_Perspec

tive.m function, the software transforms

an image captured by a known camera at

a known perspective to simulate the image

captured from an alternate perspective

and/or camera.

A straightforward interface with the

algorithm allows this to be integrated

into a variety of other programs, or used

as a standalone analysis tool. Obtaining

the platform perspective is a key step in

image chain modeling, which aids in the

design of new sensor systems.

The toolkit also is useful for simulating alternate views of a scene. This is useful for Earth-observing satellites that are

in constant motion and, therefore, are

constantly changing their perspective.

This work was done by Steven J. Lewis,

David M. Palacios, and Michael C. Burl of

Caltech for NASA’s Jet Propulsion Laboratory.

Further information is contained in a TSP

(see page 1).

This software is available for commercial licensing. Please contact Dan Broderick at

Daniel.F.Broderick@jpl.nasa.gov. Refer to

NPO-48256.

Convex Hull-Based Plume

and Anomaly Detection

A number of deep space missions have

imaged plumes at Io, Enceladus, and

other smaller bodies. These phenomena

provide valuable information regarding

these bodies. To date, this imagery has

been captured fortuitously. The ability to

utilize onboard processing to conduct

campaigns capturing large numbers of images and to detect when a plume event is

occurring would open up new mission

paradigms. Extended temporal campaigns

could provide comprehensive detail on

these events’ frequency and character.

This software enables detection of

plumes and obtrusions from irregularly

shaped bodies. It finds convex hull from

edge detection. It is very computationally efficient, and works with irregularly

shaped bodies.

Onboard plume detection will enable

much more efficient monitoring of outbursts and other dynamic phenomena.

These techniques can enable a new class

of missions to conduct long-term continuous monitoring of moons, planets,

and comets.

This work was done by David R. Thompson, Steve A. Chien, Daniel Q. Tran, and Rebecca Castano of Caltech; and Ronald Greeley

and Melissa Bunte of Arizona State University for NASA’s Jet Propulsion Laboratory.

Further information is contained in a TSP

(see page 1). NPO-48432

Pre-Filtration of GOSAT

Data Using Only Level 1

Data and an Intelligent Fil- ter to Remove Low Clouds

Software has been developed that mitigates anomalously low CO2 retrieval values, due to low-lying clouds, for improved CO2 sensing accuracy. Using

machine learning techniques, hand-labeled data was used to train intelligently

a multivariate least-squares filter using

only five input-level-one features that detect low-lying clouds over ice with more

than 99% accuracy. These input features

are simple arithmetic operations on the

input spectrum such as max, min, std,

and mean.

Performing a full CO2 retrieval from

the GOSAT (Greenhouse gases Observing SATelite) data soundings is time-intensive (at 20 minutes per sounding). As

ACOS (Atmospheric CO2 Observations

from Space) is a preparatory task for the

Orbiting Carbon Observatory-2 (OCO2) coming mission in which data volumes will be much higher, using the

GOSAT environment to test and develop intelligent filters that can predict

failed or useless retrievals before significant computational power has been

wasted is a high priority.

This work was done by Lukas Mandrake of

Caltech for NASA’sJet Propulsion Laboratory. For

more information, contact iaoffice@jpl.nasa.gov.

This software is available for commercial licensing. Please contact Dan Broderick at

Daniel.F.Broderick@jpl.nasa.gov. Refer to NPO48057.

Affordability Comparison

Tool — ACT

ACT is able to provide insight into acquisition, operational, and lifecycle affordability early in program formulation

prior to a commitment of architecture,

or anytime during the program to

change systems or subsystems. ACT analyzes different systems or architecture

configurations for affordability that allows for a comparison of total lifecycle

cost, annual affordability, cost per
22 NASA Tech Briefs, February 2014

pound, cost per seat, cost per flight (average), and total payload mass throughput. Although ACT is not a deterministic model, it does use characteristics

(parametric factors) of the architectures/systems being compared to produce important system outcomes (figures-of-merit). The outcome figuresof-merit provide the designer with information on the relative affordability of

different configurations.

ACT is spreadsheet-based and contains a set of algorithms that processes

system configuration and characteristics

to a measure of system affordability.

Parametric factors are derived from

quantifiable data about each system configuration’s attributes. An initial algorithm converts quantifiable system configuration and characteristics data into a

parametric factor for architecture/system complexity. The next set of ACT algorithms processes the complexity into

system affordability figures-of-merit.

These algorithms are initialized using

known space transportation data to “anchor” embedded values in the algorithms. While the Space Shuttle was initially used for the comparisons, a

database of other anchors is envisioned.

The algorithms allow the comparison

of standard processes embedded with

mathematically consistent values. This

will not necessarily produce an exact

forecast (deterministic cost number),

but instead provide consistent figures-ofmerit suitable for surfacing more affordable and productive alternatives.

ACT is scalable in that it can compare

architectural design concepts of largescale systems (elements) down to subsystems. Although the configuration of

these systems may be vastly different,

ACT can make functional comparisons

based on multiple system attributes.

This work was done by Carey McCleskey,

Timothy Bollo, and Jerry Garcia of Kennedy

Space Center. For more information, contact

the Kennedy Space Center Technology Transfer Office at (321) 867-5033. KSC-13714

“Ascent — Commemorating

Shuttle” for iPad

A feature-added, interactive version of

the video release entitled “Ascent” was

developed. The software version contains the full HD (high definition) movie

along with extra scenes, still imagery, a

movie trailer, and producer notes. The

software has been packed as an iOS app,

intended for use on the iPad.

The software app provides the ability

to include all features of the original

DVD and include additional interactive

features to enhance the user experience.

The distribution mechanism of Apple’s

“App Store” provides a cost-free mechanism to disseminate educational and informational NASA material to the general public.

The objective of this work was to disseminate the video released on DVD

with value-added features and without

incurring distribution and media costs.

This work was done by Gerald Nolan, Eric

Mindek, and Matt Melis of Glenn Research

Center. Further information is contained in a

TSP (see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed

to NASA Glenn Research Center, Innovative

Partnerships Office, Attn: Steven Fedor, Mail

Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-18811-1.

Cassini Mission App

This iPhone/iPad application allows

the general public to access information

about the Cassini mission. It enables

viewing of the latest images released by

the mission, allows access to images that

describe the present position of the

spacecraft, and provides flyby countdowns for each targeted flyby.

The software was developed using the

Apple iOS SDK, and utilizes components inherent to that SDK to deliver images and other content on the iOS platform. It retrieves content from the

public Cassini Web site using HTTP,

XML, and JSON.

The software is a direct link to the

general public from Cassini-related images and other information, and is intended to help spark interest in space

exploration.

This work was done by Alice S. Wessen and

Kirk Munsell of Caltech and Harman G.

Smith and Joseph A. Wieclawek III of

Raytheon for NASA’s Jet Propulsion Laboratory. Further information is contained in a

TSP (see page 1).

This software is available for commercial licensing. Please contact Dan Broderick at

Daniel.F.Broderick@jpl.nasa.gov. Refer to

NPO-47866.

Light-Weight Workflow En- gine: A Server for Executing

Generic Workflows

The Light-Weight Workflow Engine

(LWWE) is a cross-platform server that

provides support for automation and orchestration of task execution.

The workflow tool is able to automate

and orchestrate a number of independent and dependent workflow tasks that

can have dependencies on time, execution counts, and the execution status of

other tasks. These tasks perform internal or external process execution and

report execution status of those

processes, as well as being able to control tasks on a limited basis (restart, suspend at startup, abort, etc.). An example

of such tasks would be running preparation and execution scripts for scientific

models. Since execution state is tracked,

workflows are able to resume in the

event of system failure.

At NASA, users generally use run

scripts to execute large sets of commands. This is all performed within a

terminal. Monitoring the execution of

the scripts usually meant watching output or checking batch job queues. The

NASA Experiment Designer (NED)

workflow software (of which LWWE is a

component) is intended to assist in the

configuration, operation, and monitoring of these scripts. Previously the NED

software had been using the SMS software from the European Centre for

Medium-Range Forecasts (ECWMF) as

the workflow component. The LWWE

software is the replacement for SMS.

LWWE is pluggable software that can

be embedded in other software or run

standalone. The APIs include socket and

command line interfaces, as well as extension points for implementing more

complex custom tasks. External

processes such as scripts or operating

system commands can be launched and

monitored. Workflow state is persisted to

allow the engine to restart workflows

from a recently known state (with the

caveat that external processes must handle their own restart correctly).

This work was done by Shawn Freeman of

Northrop Grumman Information Systems for

Goddard Space Flight Center. Further information is contained in a TSP (see page 1). GSC16083-1

Model for System

Engineering of the

CheMin Instrument

A computer program implements a

model of the performance of the CheMin

(Chemistry and Mineralogy) instrument

— a miniaturized instrument that simultaneously performs x-ray diffraction (XRD)

and x-ray fluorescence (XRF) measurements on small material samples. The

CheMin instrument is being developed

for use in exploring Mars and possibly

other extraterrestrial bodies.
NASA Tech Briefs, February 2014 23

The model consists mostly of submodels of the XRD and XRF performance.

The model is intended to be used by the

instrument-development team for system-engineering purposes, notably including (1) verification or establishment

of the flow of requirements from scientific objectives to instrument-design and

-performance parameters; (2) assessment of effects, on performance, of

changes in design and/or nominal operating conditions; and (3) improvement

of the ability of the team to interpret

data from experiments on other instruments or on breadboard versions of instrument systems.

The model is meant to be used to

perform rapid approximate analyses of

behavior of the instrument as a whole.

It is expected that detailed examinations of higher-order effects will be

done separately. Results from those examinations should be incorporated

into the model in simplified form as

they become available.

This program was written by Curtis W.

Chen of Caltech for NASA’s Jet Propulsion Laboratory. For more information, contact iaoffice@jpl.nasa.gov.

This software is available for commercial licensing. Please contact Dan Broderick at

Daniel.F.Broderick@jpl.nasa.gov. Refer to

NPO-44702.

NASA Tech Briefs, February 2014 25

Information Technology

Timeline Central Concepts

The Timeline can be used in ground operations software for manned, robotic,

or mixed missions.

NASA’s Jet Propulsion Laboratory, Pasadena, California

The notion of Timeline has been used

informally in spacecraft operations software for some time, but it has not heretofore been formalized and unified either

syntactically or semantically. In this work,

the Timeline has been formalized and

unified so that the commonality can be

exploited to reduce the cost of developing

and using spacecraft operations software.

The Timeline can then be used as the

common data structure for storage and

communications between spacecraft planning and operations software elements.

Most spacecraft planning and operations processes are naturally expressed

in terms of software tools that read timelines from databases as input and generate results as new or modified timelines

that are written to the databases. Timelines are rigorously versioned, and each

version is immutable — thus, a versioned timeline name forever represents

exactly the same contents. The name is

therefore as good as the contents, and

the need for keeping files of contents for

communicating between programs, or

for associating several timelines or even

values on those timelines, or for keeping

a record of past values, is eliminated.

Timelines thus form the syntactic and semantic method of integration of software elements, leading to decreased

adaptation cost.

Operations efficiency is increased because historically segregated elements are

easily integrated so that there are fewer

gaps in the operations process that must

currently be closed, if they are closed at all,

by expensive or inefficient means.

The Timeline is abstractly defined as a

container of items indexed by time, or of

items related by time. The abstract definition is intentionally rather open, and the

edge between timeline and not-timeline is

fuzzy. The abstract definition does not need

to be formalized, because it is the type of

timeline that is actually defined that has

practical impact. Timelines are made practical by creating concrete types of timelines

that can be precisely defined,stored in databases, manipulated in software, and so on.

Timeline instances are stored in timeline databases (TLDBs). All TLDB instances must have two properties beyond the obvious of providing for the

storage and retrieval of timelines: they

must be rigorously versioned, meaning

that in principle every change to a timeline creates a new version of that timeline; and they must provide version immutability, meaning that once a version

is created, it is never changed. The reason for this is so that a timeline name

and version together precisely represent

the contents of that timeline at some instant in time.

The Database Interface is a key architectural invariant, along with the Timeline. It is designed to allow the database

technology to be selected to meet mission

needs. For example, a small mission may

choose to use a free database. A larger

mission may choose to use a commercial

database that provides robust hot backups, offsite mirroring, local caching, and

the like. A mission may choose to put the

data in a commercial cloud. It may even

change DB technologies over the life of

the mission, using something cheap and

light in formulation, heavy in operations,

and optimized for archival access in perpetuity. The interface stays the same no

matter what technology is used by a project, so that the spacecraft operations software suite will operate the same regardless of the DB technology used.

Interfaces can be added and extended, so that when a new timeline

major type is introduced, the interfaces

can be systematically extended to support the new timeline type.

This work was done by William K. Reinholtz of Caltech for NASA’s Jet Propulsion

Laboratory. Further information is contained

in a TSP (see page 1).

The software used in this innovation is available for commercial licensing. Please contact Dan

Broderick at Daniel.F.Broderick@jpl.nasa.gov.

Refer to NPO-48353.

Parallel Particle Filter Toolkit

Particle filters in real-time applications will bring unprecedented accuracy and applicability to

aircraft and spacecraft navigation.

John H. Glenn Research Center, Cleveland, Ohio

Research on using inexpensive and

personal-level parallel computing architectures to speed up the implementations of the class of particle filters has

been conducted. This study leverages

NVIDIA Graphics Processing Units

(GPUs) and multi-core CPUs (central

processing units) that are quickly becoming commonly available for engineering communities. Parallelization of

the unscented Kalman filter and the

bootstrap particle filter, with applications in a GPS/INS (global position system/inertial navigation system) integration problem and an orbital

determination problem, has been the

focus of this research. It has been

shown in this research that an 8-times

speedup can be achieved for the unscented Kalman filter implementations

with an 8-thread CPU, and up to 2 orders of magnitude speedup can be

achieved using an M2090 GPU.

The results also show that real-time

applications for both unscented

Kalman filters and particle filters are

feasible for the two benchmark prob-
26 NASA Tech Briefs, February 2014

lems considered. The parallelized particle filter for both benchmark problems

completes a 1-s filter cycle in under 0.23

s. It also demonstrates that parallel

modules can be made as a black box

that can interact with third-party serial

programs, but require minimum knowledge from the user on how to parallelize a problem or on how to write a

parallel program.

This research contributes to upgrading the current fleet of NASA navigation

software that heavily relies on the

Kalman filter and the Extended Kalman

Filter (EKF), which can fail in nonlinear

applications with non-Gaussian noise

models. Advanced filters, like the sigma

point and particle filters, are more accurate than the EKF for nonlinear and

non-Gaussian noise models.

One drawback of the particle-based

filters is the excessive computational

burden if implemented on a serial

computer. However, because a majority

of the computation can be carried out

simultaneously, the particle filters inherently are well suited for parallel

computing. The objective of this effort

is to leverage GPUs and multi-core

CPUs to exploit such parallelism. With

the performance of these devices improving at a rapid pace, it is anticipated

that they will quickly find their way to

onboard avionics. This research paves

the way for implementing particle filters in real-time applications. This will

bring unprecedented accuracy and applicability of particle filters to aircraft

and spacecraft navigation analyses for

NASA, and for a wide range of nonNASA applications.

This work was done by Haijun Shen and

Christopher D. Karlgaard of Analytical Mechanics Associates, Inc., and Ryan P. Russell,

Vivek Vittaldev, and Etienne Pellegrini of The

University of Texas, Austin for Glenn Research

Center. Further information is contained in a

TSP (see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed to

NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steven Fedor, Mail Stop

4–8, 21000 Brookpark Road, Cleveland, Ohio

44135. Refer to LEW-19021-1.

Particle filters (PFs) offer the possibility of addressing many unsolved problems in orbit determination and prediction. This work builds on an existing

GSRP (Graduate Student Researchers

Project) effort to incorporate a particle

filter into GSFC’s (Goddard Space Flight

Center’s) Orbit Determination Toolbox

(ODTBX). Extensions were investigated

that partition the particles into subsets

based on a priori errors, measurement

noise, process noise, and maneuver execution errors. Parallel computing was

used to efficiently implement a sufficiently large number of particles to

begin solving significantly non-Gaussian

estimation problems.

The work builds on ODBTX’s inherent capability to distribute computations

over multiple computational cores,

which will prove complementary to the

structure of the PF, since computations

involving each particle can be assigned

to their own core.

The PF estimator added to ODTBX,

when running on a multicore server, will

enable GSFC navigation analysts to

tackle previously daunting navigation

challenges, such as simultaneously determining the orbit around, and characterizing the properties of primitive solar

system bodies. It will provide a benchmark for the current suite of orbit estimators, uncovering any shortcomings

that arise from Gaussian assumptions in

the current estimators.

This work was done by John A. Gaebler,

Alinda Mashiku, and Russell Carpenter of Goddard Space Flight Center. Further information

is contained in a TSP (see page 1). GSC16608-1

A common objective for primitive body

missions (i.e., those to asteroids, comets,

and small planetary moons) is to map the

target body surface as completely as possible. Ideally, this map is constructed

from a large collection of images containing multiple views of every point on the

surface in a variety of lighting conditions

and from a variety of viewpoints. For

most missions to near-Earth objects

(NEOs), the inherent instability of the orbital environment due to solar radiation

pressure (SRP) necessitates a mapping

trajectory strategy that requires deterministic maneuvers every few days for several

weeks to achieve the desired imaging

geometries. The recently discovered

quasi-terminator orbits (QTOs) offer an

alternative approach that can achieve the

imaging geometries needed for mapping

without any deterministic maneuvers. By

eliminating the need for frequent maneuvering, QTOs can significantly reduce

the complexity and intensity of global

mapping operations for robotic or

manned missions to NEOs.

QTOs are quasi-periodic orbits that

are derived from the well-known, stable

terminator orbit solutions to the SRPperturbed orbit dynamics at primitive

bodies. Terminator orbits are not generally suitable for mapping because the

phase angle (i.e., the Sun-body-spacecraft angle) stays nearly constant around

90°, which constrains the surface viewing and illumination geometries. However, the quasi-periodic oscillatory motion around a stable terminator orbit

can be computed explicitly and ampliQuasi-Terminator Orbits for Mapping Small Primitive Bodies

These orbits enable surface mapping without maneuvers when solar pressure is strong.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Particle Filter Simulation and Analysis Enabling

Non-Traditional Navigation

Goddard Space Flight Center, Greenbelt, Maryland
NASA Tech Briefs, February 2014 27

The Subgrid-Scale Scalar Variance Under Supercritical

Pressure Conditions

NASA’s Jet Propulsion Laboratory, Pasadena, California

A quantity called “the conserved

scalar” is very important in the modeling of turbulent reactive flows in large

eddy simulations because, if it can be

defined, it numerically simplifies the solution of the conservation equations by

confining the reaction term to a singlespecies equation. This conserved scalar

is assumed to have the statistics of a beta

probability distribution function, and is

thus determined by its first two moments of the distribution. The mean is

computed as part of the general solution of the governing equations. However, the second moment, which is the

variance at the scale smaller than that of

the grid used for computation, is not

known. For subcritical-pressure flows,

an equation is usually derived for the

scalar variance, and since all terms of

the equation are not calculable from

the solution of the governing equations,

some of these terms are modeled and

the scalar variance equation is then

solved. The problem is that under supercritical conditions the scalar variance equation is considerably more

complex, a fact that begs the question

whether the same methodology can be

used for the important applications

where the pressure is very high with respect to the critical point.

The scalar variance equation was derived under supercritical conditions, its

terms were analyzed, and it was shown

that new terms never modeled before

are now important. Two methods were

devised to model accurately the scalar

variance and filtered, non-linear functions of it, such as the dissipation.

A database of direct numerical simulation was used to: (1) examine the magnitude of the new terms in the subgrid

scalar variance equation, (2) inquire

whether the scalar has a probability distribution function of presumed shape,

(3) develop directly two models for the

subgrid scalar variance, and (4) show

how these models portray non-linear

functions of the conserved scalar when

the scalar is assumed to have a presumed

probability distribution shape.

This work was done by Josette Bellan and

Enrica Masi of Caltech for NASA’s Jet Propulsion Laboratory. For more information, contact iaoffice@jpl.nasa.gov. NPO-48078.

fied using tools from dynamical systems

theory. The QTOs that result can

achieve phase angles as low as several 10s

and as high as ≈150° while retaining the

stability and robustness properties of the

terminator orbits. The resulting variety

of relative geometries allows for the surface imaging across a range of solar incidence angles, emission angles, and emission azimuths.

The QTOs have been derived using

normalized coordinates such that the solutions only depend on the relative

strength of solar pressure versus gravity

(“beta”). Applicability to a particular

mission can quickly be assessed from

published plots of orbit period, minimum radius, and maximum radius for

any mission beta. Generally speaking,

QTOs are most often applicable for beta

values corresponding to robotic missions to NEOs or manned missions to

very small NEOs.

This work was done by Stephen B.

Broschart, Gregory Lantoine, and Daniel J.

Grebow of Caltech for NASA’s Jet Propulsion

Laboratory. Further information is contained

in a TSP (see page 1). NPO-48915

ATHLETE (All-Terrain Hex-Limbed

Extra-Terrestrial Explorer) is a multipurpose mobility platform for planetary surfaces. It is a cross between a wheeled rover

and a walking robot, and travels using

powered wheels mounted on the end of

each of six robotic limbs. Each limb is a

fully articulated robotic manipulator with

six or seven degrees of freedom.

ATHLETE’s wheel-on-limb mobility

design provides great flexibility for mobility over different types of surface features. Using the wheels to drive is

highly efficient over benign terrain.

However, to support the limbed design,

ATHLETE uses wheels with lower

torque and smaller diameter relative to

the robot’s size and weight, as compared to wheeled-only rovers like the

Spirit and the Opportunity. This lowers

the overall surface pressure on the

wheels, making ATHLETE vulnerable

to slipping or embedding in soft terrain, and wheel stalling on steep terrain

when traction is good.

ATHLETE’s limbed design makes it

possible for the robot to extract itself

from such situations by locking the

wheels and employing a walking gait.

While these two mobility modes, driving

and walking, provide ATHLETE with mobility solutions over any type of terrain,

ATHLETE’ s complexity and flexibility

make possible the development of hybrid

mobility modes that combine aspects of

both driving and walking. A mobility

mode that enables faster forward

progress than walking over terrain unsuitable for driving is particularly desirable.

A new concept was developed for a

walking-driving hybrid in which wheels

are repositioned by sliding them along

the ground, rolling the wheels in coordination with the motion of the limb. This

mobility mode is referred to as the Sliding Gait, or SGait. For soft, loose, or

steep terrain, in which wheeled roving

fails, SGait enables mobility by allowing

Sliding Gait for ATHLETE Mobility

A new concept was developed for a walking-driving hybrid in which wheels are repositioned by

sliding them along the ground.

NASA’s Jet Propulsion Laboratory, Pasadena, California
28 NASA Tech Briefs, February 2014

some wheels to be repositioned while

other wheels act as anchors. Because all

six wheels maintain contact with the

ground at all times, SGait motions easily

maintain a conservative polygon of support, allowing efficient multi-limb gaits

like the alternating tripod gait to be

used for a significant time savings over

free walking. Using force feedback while

rolling wheels extends the usefulness of

SGait to terrain that is rutted, bumpy, or

strewn with small obstacles, as force control can be employed to maintain favorable wheel loading as the limb complies

to terrain features.

The SGait algorithm uses the kinematic capability of ATHLETE’s limbs to

reposition wheels independently of the

robot’s payload deck while keeping

them in contact with the ground. The

wheel is rolled along the ground in coordination with limb repositioning. This

can be done for individual wheels or

groups of wheels, allowing the approximation of any six-limbed walking gait.

Between or during wheel repositioning

motions, the payload deck is shifted to

maintain a desired stable position above

the wheels.

The SGait concept is similar to the

inching concept, but is made much

more capable by the maneuverability of

the wheel-on-limb ATHLETE mobility

system. With inching, each expansion

and contraction of the suspension system carries the rover center of gravity

(CG) forward. In the SGait implementation, however, the kinematic capability

of each limb allows the wheels to be

repositioned with minimal effect on the

CG position, which further reduces slipping in soft terrain. In addition, SGait

can conform to a variety of terrain types,

making the algorithm effective over a

wider range of surface conditions.

This work was done by Julie A. Townsend,

Curtis L. Collins, and Jeffrey J. Biesiadecki of

Caltech for NASA’s Jet Propulsion Laboratory.

Further information is contained in a TSP

(see page 1).

This software is available for commercial licensing. Please contact Dan Broderick at

Daniel.F.Broderick@jpl.nasa.gov. Refer to

NPO-47887.

Modern datasets consisting of retrievals from space-based missions have

target results, but often are accompanied by hundreds or thousands of other

retrieved parameters or facts regarding a

particular retrieval (e.g., pressure, temperature, spectral intensities). Many of

the retrieval attempts fail due to complex or contaminated soundings, wasting precious computational time. This

algorithm generates a filter based on all

available metadata regarding a run that

predicts whether it will converge or not.

Modern missions will generate so

much data that only 6% of the record is

planned on being processed by the existing slow, CPU-intensive retrieval algorithm. This algorithm generates a filter

that permits “sounding selection” to

avoid attempted retrievals that would inevitably fail and thus waste CPU cycles.

Unlike linear regressions, Fischer

analysis, or other standard machine

learning techniques that examine the

“bulk” of the data to create a “fit,” this

method utilizes a genetic algorithm that

establishes upper and lower thresholds

for each input feature. These thresholds

are then optimized with a training

dataset and reduced to the smallest

identical set of rules that generates the

same filter output. This increases scientific interpretability later as to the mechanics of the filter’s operation.

This work was done by Lukas Mandrake of

Caltech for NASA’s Jet Propulsion Laboratory.

Further information is contained in a TSP

(see page 1).

This software is available for commercial licensing. Please contact Dan Broderick at

Daniel.F.Broderick@jpl.nasa.gov. Refer to

NPO-48254.

Automated Generation of Adaptive Filter Using a Genetic

Algorithm and Cyclic Rule Reduction

NASA’s Jet Propulsion Laboratory, Pasadena, California

National Aeronautics and

Space Administration