The
Vanderbilt Haptic Paddle
Overview
The haptic paddle (shown in Figure 1) is a motorized
force-feedback joystick which allows students to feel
forces generated by interactions with various virtual
environments. It was originally developed and used as a
teaching tool for dynamic systems at Stanford
University. Since then, many universities, including
Johns Hopkins University, Rice University, University of
Michigan, and University of Utah, have contributed to the
development of this inexpensive, portable haptic device (see
the EduHaptics
webpage for more information). At Vanderbilt
University, we have incorporated the haptic paddle in the
System Dynamics laboratories (see below) and have made many
improvements in both hardware and software. These improvements
are efforts from the Medical
and Electromechanical Design (MED) Lab in the Department
of Mechanical Engineering. In collaboration with California
State University Long Beach (CSULB), we have also implemented
the haptic paddle into an Introduction to Mechanical
Engineering course and a graduate level haptics course
(materials coming soon).

Figure 1: The haptic paddle laboratory enables students to apply
theoretical concepts learned in lecture to characterize
their physical hardware, integrate it with electrical hardware,
and "close the loop" through modeling and simulation.
Innovations
We have made several improvements to the haptic paddle, making
it a more robust, portable, and inexpensive teaching device.
- Mechanical Design
- Friction-Drive Setup:
Previous haptic paddle designs required students to wind
and tighten a cable around the paddle and the motor
pulley. Our new design eliminates the tedious task of
winding the cable as well as the problems associated
with the cable breaking.
- Height Adjustment:
The height adjustment allows for easy manipulation of
the paddle handle to choose the most optimal setting for
the friction drive.
- Compact Base: The new
haptic paddle base houses the motor and the Arduino
microcontroller, making the entire system one portable
unit.
- Electrical Hardware
- Arduino
Microcontrollers: The Arduino is an inexpensive
microcontroller that easily connects to a computer via
USB and has multiple digital and analog inputs
and outputs.
- Optically encoded motors: Earlier designs of the
haptic paddle relied on hall effect sensors for sensing
motor position. We've incorporated optically encoded
motors into the latest design in order to provide
consistent feedback without requiring multiple calibration
steps.
- We also identified a new inexpensive magnetic angle
sensor that
is much more robust to misalignment with the magnet on the
paddle shaft
and also provides a larger voltage range than prior hall
effect
sensors. Lab materials are provided for both optical
encoders and
angle sensors.
- Software
- Matlab
and Simulink Models: Previously, students were given
C-executable files
to run the haptic paddle. While these files allowed
students to
interact with the paddle in a virtual environment, they
were a "black
box" to the students, limiting their learning value.
With the support
of The MathWorks,
Inc. we have transitioned all of the haptic paddle
software over to the Matlab/Simulink Environment. Using
this framework, students learn to create models of the
haptic paddle in Simulink and to interface these models
to their paddles in a closed-loop feedback control
exercise. Students also have the opportunity to develop
and interact with virtual environments in Simulink,
enabling two-way interaction with the paddles. Further,
using Matlab's built-in system identification and
analysis capabilities, students can quickly analyze a
system's response to various inputs. This new
platform allows students to take on a much greater role in
modeling and controlling the haptic paddle and the virtual
systems they interact with while simultaneously developing
valuable experience with practical engineering
software.
The primary goal in the development of the haptic paddle kit was
to minimize the cost of constructing a haptic paddle, to
accelerate classroom integration and other dissemination
efforts. Unlike high-end haptic devices which cost thousands of
dollars, the Vanderbilt Haptic paddle can be assembled for less
than $100 including all components except the PC. Another
equally important goal of the haptic paddle kit is dissemination
at all levels of education. For this reason, downloads of all
materials associated with the haptic paddle are provided below.
Course Application and Materials
At Vanderbilt University, the paddle is the focus of the ME
234 System Dynamics Laboratory. System Dynamics is
junior-level mechanical engineering course that is required
for all mechanical engineering majors at Vanderbilt, and the
laboratory is a component of the course that requires
additional meeting times outside of the lecture. In lab,
students work in small teams of 3-4 students, whom they work
with for all of the lab sessions. There are a total of 5 lab
sessions (3 hours each) in which students characterize,
construct, analyze, and interact with their haptic paddle
system. You can
check out
some of the cool lab activities on this short video!
Furthermore, below are all of the documents used in the
haptic paddle laboratory for Vanderbilt's System Dynamics
course.
- Haptic Paddle Construction
- Lab Exercises (Handouts and
Arduino/Simulink Files) Using an Analog Magnetic Angle
Sensor - The
following lab exercises use an inexpensive analog angle sensor
(~$6), to keep track of the angular position of
the motor. In
order to do this, the angle sensor must be placed
right next to a small magnet (McMaster Carr #57295K73)
mounted on the motor rotor. Note that some of
these labs require Simulink's Real Time Windows
Target, which is only currently supported on 32-bit
systems.
- Lab Exercises (Handouts and
Arduino/Simulink Files) Using an Optical Encoder - If you already have
encoded motors, the following lab exercises may be
better suited for you, as they use an optical
encoder to track motor position.
In collaboration with CSULB, the Haptic Paddle is also being
used at both the introductory undergraduate and graduate
level. In MAE 101B, an undergraduate Introduction to
Mechanical Engineering course, students use the haptic
paddle to explore the concepts of Hooke's Law and equivalent
stiffness of springs in series and parallel configurations.
In MAE 578, a graduate Haptic Systems for Virtual Reality
and Teleoperation course, students will design and analyze a
haptic simulation in Matlab using the haptic paddle.
Materials for both of these CSULB courses will be coming
soon!
Education Research
In a course on dynamic systems, having the
capability “to feel what the system feels” is beneficial in
developing intuition and conceptual understanding. In
order to assess the effectiveness of the haptic paddle
laboratories in increasing student understanding, we have
expanded and enhanced preliminary studies on haptic paddle
effectiveness, resulting in a rigorous assessment of student
learning in in-class lectures, labs, and in-lab instructions
independently. We developed 25 conceptual, multiple choice
questions (5 questions per laboratory), that relate to the
specific key concepts students should learn from the haptic
paddle laboratories. We administered all 25 questions at
the start of the semester in order to assess students' initial
understanding of the course material, and we administered the 5
relevant questions at the time of each lab. Since we have
4 student sections, we were able to administer the quiz at
different times during the lab including 1) at the beginning of
lab, 2) after an oral lab introduction that addresses the
questions, 3) at the end of the lab session, and 4) at the
beginning of the next lab (after the students completed the lab
reported). Both the 25 question assessment, and the lab
quizzes can be downloaded
here.
The results of a
two-year analyses suggest an overall increase in student
understanding from before and after lab in all of the lab
assignments. Please read our
2012
ASEE paper for an in-depth discussion of our results.
Acknowledgements
This project was supported in part by a Curriculum Development
Grant sponsored by
The MathWorks, Inc.
Papers:
1. J. L. Gorlewicz, L. B.
Kratchman, and R. J. Webster III.
Enhancements and Formal Assessments of the Haptic
Paddle. Computers and Education, 2012.
(Submitted).
2. J. L. Gorlewicz and R. J. Webster III.
A formal assessment of the
haptic paddle laboratories in teaching system dynamics.
American Society of Engineering Education, 2012.
Posters:
1. J. L. Toennies and
D. C. Rucker. Getting a Feel for
Dynamic Systems. Presented at CIRTL TAR Symposium and Vanderbilt
University Graduate Research Symposium, 2009.
2. J. L. Gorlewicz and R. J. Webster III. A Hands-On Approach to
Teaching System Dynamics. Presented at National CIRTL
Forum, 2011.