The salient features of the optical layout of a desktop-scale virtual-reality system that is specialized for simulating a glove-box work space are depicted and described

Boyle, R. D.

Smith, J. D.

Twombly, I.

NASA Technical Reports Server

place when the band clamp is tightened.
The procedure for assembling the
cable, the backshell, and the rest of the
connector is the following: The cable is
placed through the coupling nut on the
backshell body, the insulation on the
cable wires is stripped back, and each
wire is crimped to a connector pin. The
pins are inserted in the connector. The
coupling nut is threaded onto the con-
nector. The shield (assumed to made of
braided wire) pulled through the hole
on the cover. Tape is wound around the
cable near the left end of the backshell
to provide strain relief. The cover is
latched in place on the backshell body.
The band clamp is tightened around the
cover/backshell-body assembly with the
shield squeezed between the cover and
the band clamp. Once electrical conti-
nuity between the shield and the back-
shell has been verified, the shield is
trimmed and the cable is examined for
proper strain relief.
If the cable is unshielded or if termi-
nation of the shield is not needed, then
except for omission of the steps involv-
ing the cable shield, the assembly proce-
dure remains as described above. The
design of the backshell for such a case
can also remain the same, except that
optionally, the hole near the left end of
the cover can be eliminated because it is
not needed.
This work was done by Chuong H. Diep
of Hamilton Sundstrand Space Systems Inter-
national, Inc. for Johnson Space Center.
Title to this invention, covered by U.S.
Patent No. 7,044,795, has been waived under
the provisions of the National Aeronautics and
Space Act {42 U.S.C. 2457 (f)}. Inquiries con-
cerning licenses for its commercial development
should be addressed to: 
Gregory Stephenson, 
Assistant Intellectual Property Counsel
Hamilton Sundstrand
One Hamilton Road
Windsor Locks, CT 06096-1010
Refer to MSC-23670-1, volume and num-
ber of this NASA Tech Briefs issue, and the
page number.
Cable
Shield
Cover
Backshell
Body
Connector
TapeShielded
Cable
Band
Clamp
External Shield
Termination
Band Clamp
Providing 
Strain Relief And
Shield Termination
PARTLY EXPLODED VIEW
ASSEMBLY VIEW
NASA Tech Briefs, February 2009 13
The Cable Shield Is Terminated on the Outside of the backshell instead of on the inside as in a traditional design. The mechanical and electrical integrity
of the shield termination is ensured by squeezing of the shield between the cover and the band clamp.
The figure depicts salient features of the
optical layout of a desktop-scale virtual-re-
ality system that is specialized for simulat-
ing a glove-box work space. The system
generates stereoscopic left- and right-eye
images of the interior of the work space
that show (1) a user extension (defined
here as an arm, hand, and/or one or
more of the fingers on the hand of a user)
and (2) either a real or a virtual workpiece
to be manipulated by the user extension.
The positions and orientations of the user
extension and workpiece in the virtual im-
ages coincide substantially with those of
the real user extension and of the real
Glove-Box or Desktop Virtual-Reality System 
Multiple remote users can participate in a realistic simulation of a work space.
Ames Research Center, Moffett Field, California
https://ntrs.nasa.gov/search.jsp?R=20090008647 2019-08-30T06:14:35+00:00Z
14 NASA Tech Briefs, February 2009
workpiece if one exists. The images are
compensated for the non-central positions
of the user’s eyes relative to a viewing
screen on which they are presented. 
The system consists of three major
parts: the physical work space, a com-
puter subsystem, and a display subsys-
tem. In addition to the user extension,
the physical work space contains sensors
that track the position and orientation
of the user extension, sensors that track
the positions of the user’s eyes, and sen-
sors that track the position and orienta-
tion of the workpiece (if any). Option-
ally, attached to the user extension is a
pen-style haptic device — an assembly
that can include actuators that apply
forces to the end of a pen stylus held by
a user to simulate contact between the
stylus and a virtual workpiece. The sen-
sor readings are digitized in real-time
and sent to the computer subsystem. 
The computer subsystem runs soft-
ware, denoted a simulation engine, that
simulates the manipulation of the work-
piece by the user extension. The simula-
tion engine includes mathematical mod-
els of all relevant aspects of the
three-dimensional geometry and physi-
cal properties of the user extension and
the workpiece, and calculates interac-
tions between objects using a physics
based force model. The simulation uti-
lizes the tracking data provided by the
sensors plus stored data (denoted virtual
data) on the dimensions and physical
properties of the user extension and the
workpiece. The simulation can include
such details as the positions and orienta-
tions of finger segments, contact forces
with the stylus, and even deflections of
the workpiece if the workpiece is a de-
formable body. 
The output of the simulation engine
is fed to a software module that gener-
ates nominal left- and right-eye views for
eyes that are spaced apart by an amount
that can be adjusted to match the inter-
pupillary distance of the user. The views
are then processed by a software module
that uses the eye-tracking sensory data to
correct for the deviation of the user’s eye
positions from nominal viewing posi-
tions. An important part of the view-cor-
rection module is a submodule in which
the geometry of the viewing screen and
the user’s eyes is represented by means
of an asymmetric frustum that is repeat-
edly updated in response to the eye-
tracking data. 
The outputs of the view-correction
module are synchronized by an align-
ment submodule, then fed to the display
subsystem, wherein two display devices
generate the left- and right-eye images.
The images are projected onto the view-
ing screen through circularly polarizing
filters, such that the left and right im-
ages are polarized orthogonally to each
other. The user wears a pair of corre-
spondingly polarized eyeglasses so that
the left or right eye sees only the left or
right image, respectively. 
A somewhat more complex version of
the system can include two or more physi-
cal-work-space/display subsystem assem-
blies, possibly at different locations. The
simulation engine from each work-space is
connected via a network to the other sim-
ulation engines. This system would make it
possible for multiple remote users to work
together, or simulate working together, on
the same workpiece. 
This work was done by J. D. Smith and R.
D. Boyle of Ames Research Center and I.
Twombly of Universities Space Research.
This invention is owned by NASA and a
patent application has been filed. Inquiries con-
cerning rights for the commercial use of this in-
vention should be addressed to the Ames Tech-
nology Partnerships Division at (650)
604-2954. Refer to ARC-14756-1.
User
Polarizing
Eyeglasses
Mirror
Virtual
User Extension
Real
User Extension
Box
Enclosing
Work Space
Real
Workpiece
Virtual
Workpiece
Left and
Right
Display
Devices
Polarizing
Filters
Viewing
Screen
OPTICAL LAYOUT
BLOCK DIAGRAM
Physical Work Space
Workpiece-
Tracking Sensors Input/
Output
Signal
HandlerUser-Extension-
Tracking Sensors
Eye- Tracking
Sensors
Viewing
Screen
Haptic Device
Virtual Data
Simulation Engine
View Module
Left-Eye
View
Right-Eye
View
View-Correction
Module
Asymmetric-
Frustrum Submodule
Alignment
Submodule
Computer Subsystem
Mirror
Display Subsystem
Polarizing
Filters
Left and
Right
Display
Devices
Polarizing
Eyeglasses
This Virtual-Reality System simulates a work space immediately in front of the user, as in a glove box. The
system generates stereoscopic images that are compensated for changing positions of the user’s eyes.


Glove-Box or Desktop Virtual-Reality System

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