This project
aimed to create a pre-process module, named DDEX, for rigid body
Dynamic Data EXtraction from Computer Aided Design geometric models.
It was developed to be used as part of the design analysis cycle of
the International Space Station (ISS).
DDEX was
developed to be a part of the Synergistic Engineering Environment
(SEE). The SEE is being used at the National Aeronautics and Space
Administration as an advanced engineering analysis and planning tool
for space operations. The SEE software integrates accurate geometric
models of spacecraft, such as the International Space Station, with
engineering data to allow users to perform real-time interactive
engineering analysis. ISS being an International project,
coordination among all engineers was an important issue, as were the
maintenance and modification of the development tools. SEE was aimed
to address all these issues.
The official Design Analysis Cycle (DAC) model of the
ISS consists of over one hundred configurations representing
different stages of the station. Each configuration consists of up
to 28 rigid bodies while each rigid body is an assembly formed by
subassemblies and elements. There are over four hundred individual
elements within a CAD model of the station. DDEX generates a text
file with all the parameters required by the analysis tool. The
focus in this research was on two CAD Systems – 1. IDEAS and, 2.
Pro/Engineer.
In order to
perform a rigid body dynamics analysis of the space station, we need
to obtain mass properties, inertia properties, and the locations and orientations
of joints from the CAD model of the station. This
information is also required by the visualization part of the
application to simulate the analysis data generated by the dynamics
analysis tools. In addition, in order to display the station with a high level of
detail within the ISS SEE, a program is desired to automatically
generate the high-fidelity geometry files of all elements from the
CAD model of the station. The DDEX module was designed to achieve
these goals, without human intervention.
Two I-DEAS
model files consisting of over 80 DAC 8 configurations were obtained
from NASA LaRC. Once the DDEX files are extracted using the
module, the user can load a configuration into the ISS environment
by choosing the corresponding DDEX file from the configuration
library. The user can also import an individual element from the
element library, move the elements within the configuration, and
save the modified configuration into a new DDEX file. The new DDEX
file is then fed into the dynamics tools for the calculation of
rigid body dynamics analysis for the new configuration. The main
application then simulates the results. Thus, DDEX has contributed
significantly to the SEE program.
