NASA Technical Reports Server (NTRS) 20090020618: Optimized Geometry for Superconducting Sensing Coils

0.31 MB·English

by  NASA Technical Reports Server (NTRS)

using the attitude/position instrumen- algorithms for a variety of applications Lam, and Patrick Meras of Caltech for
tation. This resulted in providing test including precision Lunar landing al- NASA’s Jet Propulsion Laboratory.
and validation of an imaging lidar, and gorithm development. The software used in this innovation is
has the capability to test other types of This work was done by James Alexander, available for commercial licensing. Please
surface terrain imaging sensors during Hannah Goldberg, James Montgomery, Gary contact Karina of the California Institute of
aerial field tests. This task thus pro- Spiers, Carl Liebe, Andrew Johnson, Kon- Technology at (626) 395-2322. Refer to
vides data and truth measurements to stantin Gromov, Edward Konefat, Raymond NPO-44581.
Robot Electronics Architecture
Key features are modularity and expandability.
NASA’s Jet Propulsion Laboratory, Pasadena, California
An electronics architecture has been data- and power-bus circuitry]. This feature PC/104 footprint.
developed to enable the rapid construc- also enables minimization of development The architecture includes several user-
tion and testing of prototypes of robotic costs through selection of off-the-shelf and system-friendly features: Two inde-
systems. This architecture is designed to PC/104 components whenever possible. pendent inputs for panic buttons or
be a research vehicle of great stability, re- Particularly notable is a capability for watchdog functions enable manual, com-
liability, and versatility. A system accord- modular expansion to enable a single puter, or watchdog disablement of any or
ing to this architecture can easily be re- central processing unit (CPU) to super- all boards, without affecting the computer.
configured (including expanded or vise the simultaneous operation of a An independent circuit holds all actuators
contracted) to satisfy a variety of needs practically unlimited number of actua- inactive until the computer sends an en-
with respect to input, output, processing tors. For this purpose, the architecture abling signal. A single switch overrides all
of data, sensing, actuation, and power. provides for each actuator a modular functions to enable manual control.
The architecture affords a variety of real-time control subsystem, independ- Lights, test points, and outputs enable
expandable input/output options that ent of other such subsystems. The subsys- both the user and the computer to inde-
enable ready integration of instruments, tem contains dedicated electronic hard- pendently monitor the state of the board
actuators, sensors, and other devices as ware that drives the actuator to execute and internal circuit functions.
independent modular units. The separa- continuously updated arbitrary motions. This work was done by Michael Garrett,
tion of different electrical functions onto The architecture includes a provision for Lee Magnone, Hrand Aghazarian, Eric
independent circuit boards facilitates the control feedback in the form of outputs Baumgartner, and Brett Kennedy of Caltech
development of corresponding simple from any or all of a variety of sensors. Any for NASA’s Jet Propulsion Laboratory.
and modular software interfaces. As a re- or all actuators can be run independ- In accordance with Public Law 96-517, the
sult, both hardware and software can be ently and motions updated instantly, contractor has elected to retain title to this in-
made to expand or contract in modular without reference to any prior motion vention. Inquiries concerning rights for its com-
fashion while expending a minimum of profile. mercial use should be addressed to:
time and effort. A custom actuator-driver circuit board Innovative Technology Assets Management,
To ensure modularity and reconfigura- has been developed for this architecture JPL, Mail Stop 202-233, 4800 Oak Grove
bility, the architecture incorporates the to satisfy some power and mass con- Drive, Pasadena, CA 91109-8099, (818) 354-
PC/104 standard [an industry standard for straints pertaining to a specific applica- 2240, E-mail: [email protected].
compact, stackable modules that are fully tion. This board is capable of driving 12 Refer to NPO-41784, volume and number
compatible (in architecture, hardware, motors simultaneously under computer of this NASA Tech Briefsissue, and the page
and software) with personal-computer control and is built on a standard number.
Optimized Geometry for Superconducting Sensing Coils
Design would minimize measurement time in magnetic resonance imaging.
NASA’s Jet Propulsion Laboratory, Pasadena, California
An optimized geometry has been pro- to maximize the sensitivity of the detector to maximize the magnetic flux enclosed
posed for superconducting sensing coils of which the coil is a part, subject to geo- by the sensing coil while minimizing the
that are used in conjunction with super- metric constraints arising from the prox- self-inductance of this coil. Simply making
conducting quantum interference devices imity of other required equipment. In the coil larger may increase its self-induc-
(SQUIDs) in magnetic resonance imag- MRI or MEG, the main benefit of maxi- tance and does not necessarily increase
ing (MRI), magnetoencephalography mizing the sensitivity would be to enable sensitivity because it also effectively in-
(MEG), and related applications in which minimization of measurement time. creases the distance from the sample that
magnetic fields of small dipoles are de- In general, to maximize the sensitivity contains the source of the signal that one
tected. In designing a coil of this type, as of a detector based on a sensing coil cou- seeks to detect. Additional constraints on
in designing other sensing coils, one seeks pled with a SQUID sensor, it is necessary the size and shape of the coil and on the
NASA Tech Briefs, January 2008 7
distance from the sample arise from the would be realized by constructing each
fact that the sample is at room tempera- turn of the coil in the form of a thin washer.
0.07
ture but the coil and the SQUID sensor Moreover, in the case of a four-turn coil in
must be enclosed within a cryogenic a second-order gradiometer arrangement
0.06
shield to maintain superconductivity. (see figure), it would be beneficial to axially
One element of an approach to in- separate the two middle turns in order to
0.05
Units cinrecraesiansgin gs esnizseit iivs ittoy iwnictrheoauset tahpep nreucmiabbelyr fbueretnh eer striemdautceed ththea ts eflof-ri nadnu cMtaRncI ec. oIitl hdaes-
ary 0.04 of turns, subject to the requirement to signed according to the present optimized
bitr maintain an impedance match with the geometry, the increase in sensitivity over
Ar 0.03 SQUID sensor. On the other hand, sim- that of the corresponding conventional
y,
etr ply increasing the number of turns also wire-wound coil would make it possible to
mm 0.02 increases the self-inductance. One way to reduce measurement time by a half.
Sy effect a substantial reduction in induc- This work was done by Byeong Ho Eom,
xis of 0.01 tance without reducing the number of Konstantin Penanen, and Inseob Hahn of
A turns is to make the coil of a thicker wire Caltech for NASA’s Jet Propulsion Laboratory.
g
on 0.00 and/or to shape the wire to other than a Further information is contained in a TSP (see
Al commonly available circular or square page 1).
n
ositio–0.01 cSreonsssi nsgec Ctiooinls, faosr dSeQscUrIibDesd” (iNn P“OIm-4p4r3o9v7e)d, conItnr aacctcoorr dhaans ceel ewctietdh tPou rbeltiaci Ln atwitl 9e 6to-5 t1h7is, tihne-
P
NASA Tech Briefs, Vol. 31, No. 10 (Octo- vention. Inquiries concerning rights for its
–0.02
ber, 2007), page 26. On the other hand, commercial use should be addressed to:
the allowable increase in size and change Innovative Technology Assets Management
–0.03
0 0.01 0.02 0.03 0.04 in shape of the wire is limited by the JPL
Radius, Arbitrary Units above-mentioned geometric constraints Mail Stop 202-233
pertaining to enclosure in the cryogenic 4800 Oak Grove Drive
This False-Color Plotrepresents half-meridional- shield and distance from the sample. Pasadena, CA 91109-8099
plane contours of the magnetic field that would Taking all of the aforementioned consid- E-mail: [email protected]
be generated by driving current through the
four washerlike turns of an optimized second- erations into account, it was found that for Refer to NPO-44629, volume and number
order gradiometer sensing coil of the type de- both SQUID MRI and SQUID MEG, the of this NASA Tech Briefsissue, and the page
scribed in the text. optimum or nearly optimum coil geometry number.
Sensing a Changing Chemical Mixture Using an Electronic Nose
ASIC may enable continuous, high-speed monitoring.
NASA’s Jet Propulsion Laboratory, Pasadena, California
A method of using an electronic nose a variety of chemicals. By design, each equivalent to a computational architec-
to detect an airborne mixture of known sensor is unique in its responses to these ture known in the art as a space-invariant
chemical compounds and measure the chemicals: some or all of the sensitivities ICA architecture. In principle, this archi-
temporally varying concentrations of of a given sensor to the various vapors tecture is amenable to implementation in
the individual compounds is undergo- differ from the corresponding sensitivi- an application-specific integrated circuit
ing development. In a typical intended ties of other sensors. In general, the re- (ASIC). The anticipated future develop-
application, the method would be used sponses of the sensors are nonlinear ment of such an ASIC would make it pos-
to monitor the air in an inhabited space functions of the concentrations of the sible to construct a miniature, high-
(e.g., the interior of a building) for the chemicals. Hence, mathematically, the speed, low-power electronic-nose sensor
release of solvents, toxic fumes, and monitoring problem is to solve the set of system for continuous monitoring.
other compounds that are regarded as time-dependent nonlinear equations for This work was done by Tuan Duong and
contaminants. At the present state of the sensor responses to obtain the time- Margaret Ryan of Caltech for NASA’s Jet
development, the method affords a ca- dependent concentrations of individual Propulsion Laboratory.
pability for identifying and quantitating compounds. In accordance with Public Law 96-517,
one or two compounds that are mem- In the present developmental method, the contractor has elected to retain title to this
bers of a set of some number (typically successive approximations of the solution invention. Inquiries concerning rights for its
of the order of a dozen) known com- are generated by a learning algorithm commercial use should be addressed to:
pounds. In principle, the method could based on independent-component analy- Innovative Technology Assets Management,
be extended to enable monitoring of sis (ICA) — an established information- JPL, Mail Stop 202-233, 4800 Oak Grove
more than two compounds. theoretic approach for transforming a Drive, Pasadena, CA 91109-8099, (818)
An electronic nose consists of an array vector of observed interdependent sig- 354-2240, E-mail: [email protected].
of sensors, typically made from polymer- nals into a set of signals that are as nearly Refer to NPO-42213, volume and number
carbon composites, the electrical resist- statistically independent as possible. The of this NASA Tech Briefs issue, and the
ances of which change upon exposure to algorithm can be characterized as being page number.
8 NASA Tech Briefs, January 2008