An online ergonomic evaluator for 3D product design

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3.2. Web-based GUI
The web-based graphical user interface (GUI) is
embedded in Microsoft Explorer 6.1 using simple
HTML format. Java Server Pages (JSP TM ) technology
connects the viewer to multi-media data sources
within a browser environment. A variety of languages
like JavaScript, VBScript, and DHTML provide
effective tools for the GUI implementation in a JSP
program. The GUI also enables instant communications
between the system and the user with integration
with standard Windows UI components.
3.3. Server technology
This system adopts Apache Tomcat TM as a web
application server that links the 3D viewer embedded in
the web-based GUI and the reference engines (posture
generator and ergonomic evaluation engine) at the back
end. A commercial Java SDK–JXL TM offers an interfacing
technology for the data transfer between the
viewer and the posture generator constructed in Microsoft
Excel TM spreadsheets, or related rule databases.
3.4. Posture generator
The human templates produce a variety of postures
required in ergonomic evaluation. It is constructed from
a massive amount of the body motion data captured with
a full-scale high-speed camera. Different patterns of
human configuration are recognized from the captured
data using data mining techniques [42], andtheresults
are stored in Microsoft Excel TM spreadsheets. Each
template usually corresponds to a set of coordinate
transformations for various body parts involved in the
generation of a particular posture. These spatial
relationships exist in Excel TM tables and drive the
configuration change of the digital human in the viewer
through SpinFire SDK and its internal mathematical
functions. This posture generator also offers the viewer
the detailed dimensions of any chosen human model. It
also passes the posture data along with the user inputs
over to the evaluation engine.
3.5. Ergonomic evaluation engine
The system currently allows ergonomic evaluation
for a set of sitting postures using a two-dimensional
C.-F. Kuo, C.-H. Chu / Computers in Industry 56 (2005) 479–492
statically biomechanical model. The evaluation result
consists of the compression as well as shear forces on
L5/S1 and moments/forces at critical joints of the
upper limbs including shoulder, elbow, and wrist. The
corresponding formulae are explicitly expressed in
Excel TM and all the related computations are
performed with VBA. The posture generator provides
the pose data required in the evaluation through direct
binding between two Excel threads. The engine then
sends the outcome over to the user via the application
server in HTTP protocol. The viewer is running a
socket thread pending for the response from the
engine. The server will refresh the browser and publish
with the evaluation data. Note that more biomechanics
models can be readily appended into the engine for
other ergonomic evaluations.
4. Implementation and discussions
4.1. Scenario I
We illustrate two scenarios that demonstrate on-line
design evaluation for ergonomics using the proposed
system. In the first scenario, the user remotely opens up a
browser embedding with the 3D viewer via the Internet
and establishes a HTTP link to the server, as shown in
Fig. 4. The main page consists of three modules. The left
one (L) provides a set of UI’s withwhichtheusercan
query geometric information in the current design. The
middle area (M) contains a 3D display space of the
viewer and a history data access area. The user can
change the pose of the digital human with the joint
angles keyed in from the right module (R). The
evaluation process generally consists of the following
steps shown in Figs. 5–8, respectively:
(1) Choose an interior design from the drop down
menu in middle module.
(2) Generate preferable 3D views and record them for
future evaluation.
(3) Measure the dimensions in 3D space that
determine the comfort of the current interior
setting.
(4) Calculate the corresponding joint angle (the hip
angle in this case).
(5) Repeat (4) and (5) for each joint angle (six angles
to be determined in this example).