About WEAVE
The weave centers around the use and development of web-based instructional modules
characterized by the following attributes:
- An interactive tutorial describing the system, numerical model and physical experiment.
Many of theses tutorials feature interactive learning guides developed by the Shodor Education Foundation.
- Sensors, data acquisition and control hardware for the remote
experiment, monitored and made accessible by a web client.
Data acquisition
and realtime control use custom software and/or the
Matlab Data Acquisition Toolbox.
- An integrated numerical model featuring data input, software capable of solving
a system of equations in the background, and graphical representation of
the results, including interactive plots and animations.
- Repeatability in the experiment and simulation, allowing students to make comparisons
and explore the possibilities available through engineering design.
- An anonymous feedback utility for students to provide input and suggestions
for module improvement.
We believe that these characteristics of the modules will ensure the capability
of the weave to address the instructional needs outlined above.
A central theme of the weave project has been to provide the enabling technology
for faculty to place both experimental and numerical simulations on the web
with a minimum of technical expertise. The exibility of the weave 's basic structure (i.e. the
framework linking all of these characteristics together) allows several different modules to be
developed by replacing each of the required components. The project
is presently funded by a grant from Duke University's
Center for Instructional Technology
(CIT)
and the National Science Foundation
(NSF).
Support in development of interactive learning tools is provided by the
Shodor Education Foundation.
In what follows we provide a brief history of the project as well as
some details of the current instructional modules.
History
The inspiration for the weave project stems from common experiences of the mechanics
faculty within the Pratt School of Engineering at Duke University.
These experiences concern both research and undergraduate instruction,
and center on the lack of a robust technology for visualizing models
and experiments side by side. Such a technology would greatly facilitate
the introduction of advanced theoretical concepts in the classroom
as well as provide a unique research tool.
In the Fall of 2000, the office of Duke's president Nan Keohane announced a
call for proposals from faculty to develop innovative undergraduate
instruction projects. At this time, the basic concepts for weave
were suggested by CEE faculty Henri Gavin and John Dolbow. After
receiving this initial seed funding from the president's office,
these faculty proceeded to obtain a larger grant from Duke's CIT.
The goal of this initial stage was to develop the weave and the
initial pilot instructional module.
The success of the weave and its associated instructional modules depends heavily
on faculty-student interaction for both construction and use. The
intention is to develop modules by having faculty-lead teams of
both graduate and undergraduate students put these modules together.
In this manner, the development of the modules should provide excellent
initial training for engineering graduate students as well as a
"research experience" for undergraduates. This philosophy
was adhered to during the development of the weave and its first
module. More information about other significant contributors to
this project can be found on the
contact page.
Architecture
At the heart of the weave is a central web server housed in the basement
of the Engineering Annex, Room 053 in Hudson Hall. This web server links student users
over the internet to actual physical experiments and accompanying numerical simulations.
By pressing a button on a web page, students can initiate the start
of an experiment in real time whose measurements will be subsequently
displayed on the same page. Modifications can be made to the inputs
to the experiments, and the cause-and-effect realtionships realized
via the web. By the same token, students can adjust model parameters
in order to try to obtain a reasonable correlation between the numerical
simulations and the displayed experimental data.
The basic architecture that allows this to happen is shown above. In
addition to the web server, the main weave server houses numerical
programs developed by individual faculty (written in either Matlab
or C), a Matlab Web server, and data acquisition utilities. Over
the network, these are connected to additional local machines serving
the experiments for each module. These local machines are responsible
for sending appropriate signals to actuators connected to the experiments
and for retrieving the pertinent experimental data. This DAP server
and numerical programs are therefore the only additional items necessary
to develop new instructional modules.
The system identifed for the pilot module consists of a minature shaking
table connected to a linear actuator, and represents a model to
investigate the earthquake response of structural systems. A mock-up
of the module is shown to the right. The interactive tutorial preceeding
this page walks students through a description of the experiment,
the relevance of the numerical model and links to present research
in the area. Students can specify a number of different time-dependent
load signals to be applied to the base of the structure, and sensors
measure local accelerations and velocities. The results of these
measurements are displayed on the modules web page, along with the
output from the numerical model. The numerical code solves a simple
ordinary differential equation modeling a spring-mass-damper system,
and students can adjust each of the relevant physical parameters.
Students can also choose to download and view a select number of
pre-recorded videos of the experiment that have been cataloged to
specific input signals.
Hardware for Physical Simulations
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| Building Vibrations |
Tuned Vibration Absorber |
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| Gantry Crane Control |
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| System Implementation |
Parts List for the On-Line Experiments
Data Acquisition and Control, and Live Video
(1) Measurement Computing PCI-DAS1602/16 Multifunction Analog & Digital I/O
(3) Axis 205 Network Cameras
Building Vibrations
(1) MB Electronics/Dynamics 2250MB Amplifier
(1) MB Electronics/Dynamics EA1500/Modal 50 Exciter
(4) Silicon Designs 2210-010 Acclerometers
(1) ALM PA4-8-2 Linear Bearing
(4) Aluminum Plates with bottom hold taps (building floors)
(4) Aluminum strips (building columns)
(1) Solid State Relay
Tuned Vibration Absorber
(1) H2W Technologies, Inc. NCC20-18-020-1X Moving Coil Linear Actuator
Serial # F406
(1) RS-385SH-2270 RD522Z05 DC Motor from McMaster Carr
(1) Silicon Designs 2210-010 Accelerometer
Aluminum Plates
Toothed beam
Miscellaneous lumber
Gantry Crane Control
(1) Electro-Craft Corporation Permanent Magnet Servo Motor-Tach - Model E570
(1) Spectral 5kOhm Potentiometer
(1) 10kOhm Potentiometer
(1) Advanced Motion Controls Brush Type PWM Servo Amplifier model 25ABD
(1) Unipower Corporation Model ES-101 Power Supply, 24V, 25A
Aluminum Plates
(1) Solid State Relay
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Current Amplifier for the Tuned Vibration Absorber module |