The document summarizes a study that used a virtual rehabilitation system called PiP to track patients' center of pressure (CoP) over multiple exercise sessions. It found that: 1) The PiP system displayed CoP coordinates in real-time and recorded displacement throughout sessions to determine balance instability. 2) Plots of sample data showed expected reductions in maximum CoP excursion for a patient who did exercises over 8 weeks, indicating progress in balance. 3) Decreases in anterior-posterior and medial-lateral maximum excursion values when plotted against number of sessions demonstrated patient improvement over rehabilitation.

1. Results
• The PiP system displays the CoP coordinates relative to the WBB's
coordinate system in real time as depicted on Fig. 4, and 5.
• The CoP displacement is recorded throughout an entire session in
order to determine how unstable the patient is during the session.
• The plot depicted in Fig. 4, demonstrates the expected CoP
maximum excursion range recorded during a session conducted for
a typical patient with impairments in balance.
• The plot in Fig. 5, demonstrates the expected CoP maximum
excursion range recorded for the same patient after participating in
20 sessions of exercises (20 minutes each) over an 8 week period
based on previous studies [2].
Fig. 4. Sample data after an exercise performed during a week 1 session.
Fig. 5. Sample data after an exercise performed during a week 8 session.
PiP Virtual Rehabilitation System
K. Rodriguez1, B. Mohazab1, F. Mansuri1, V. Hazelwood1, H. Kambic1, A. Valdevit1, M. Majsak2
1Stevens Institute of Technology, Hoboken, NJ
2New York Medical College, New York, NY
Materials and Methods
Fig. 1. Functional Block Diagram depicting how the components of the PiP
system are connected to relay information.
• The system is calibrated by entering the patient’s mass.
• The patient’s skeleton (i.e. joint markers) is detected by the KW and
displayed on the monitor.
• The user can now enter the location of the target (left or right),
diameter of the target (cm) and duration of the target (seconds).
• Targets specified by the user are then to be reached by the patient.
• The patient is successful in reaching the target when the patient’s
palm marker has reached the target in the virtual setting.
• The WBB collects CoP coordinates in the (A/P) and (M/P) directions
throughout the exercise.
• Collected data is saved for post-session analysis in order to monitor
progress in balance improvement.
Materials and Methods
• Kinect for Windows (Microsoft, Redmond, WA, USA)
• Nintendo Wii Balance Board (Nintendo, Kyoto, Japan)
• Hewlett-Packard EliteBook 8560w Mobile Workstation (Hewlett-
Packard, Palo Alto, CA, USA)
• MathWorks MATLAB R2013a (MathWorks, Natick, MA, USA)
• Samsung 32” television (Samsung, Seoul, South Korea)
Fig. 3. Visual representation of the PiP system's components in a typical
clinical setup.
Discussion
• The goal of the project is to develop an engaging rehabilitation
system that can be modified to meet the unique needs of each
patient.
• The maximum A/P and M/L excursion ranges or A/Pmax and M/Lmax,
respectively, can be determined from the recorded data.
• A decrease in A/Pmax and M/Lmax is indicative of patient progress.
• These values can be plotted against the number of sessions
• Downward trends in value demonstrate how well a patient has
progressed throughout the course of their rehabilitative program.
Fig. 6. Sample data depicting expected A/P maximum over number of
sessions.
Fig. 7. Sample data depicting expected M/L maximum over number of
sessions.
References
1. R. Klepps. 8 Thought-Provoking Facts About Physical Therapy You Can’t Ignore. Theravid
Inc, 2013
2. W. Young, S. Ferguson, S. Brault, C. Craig, “Assessing and Training Standing Balance in
Older Adults: A Novel Approach Using the Nintendo Wii Balance Board.” Gaitpost, vol. 33,
pp. 303–305, February 2011.
3. P. Henry, M. Krainin, E. Herbst, X. Ren, D. Fox, "RGB-D Mapping: Using Kinect-Style
Depth Cameras for Dense 3D Modeling of Indoor Environments.” IJRR, vol. 31, pp. 647-
663, April 2012.
Introduction
• In the United States, 70% of patients in traditional rehabilitation
programs fail to complete their prescribed plan of care as a result of
a lack of engagement to the program [1].
• Virtual rehabilitation, which utilizes video game technology to
rehabilitate patients, is a more cost effective and engaging alternative
to traditional therapy which can increase patient participation and
completion rate of an exercise program.
• The foremost issue with current competitors is the presence of preset
difficulties.
• The Wii Balance Board (WBB) has built in pressure transducers
allowing it to assess force distribution and the resultant movements
in center of pressure (CoP).
• The Kinect for Windows (KW) is a motion sensing input device that
provides video output to design engaging, therapeutic exercises.
• The PiP system serves to provide an engaging virtual setting for
physical therapy patients while allowing users to design programs
that can be further customized past preset difficulties.
Acknowledgments
We would like to thank our academic advisors Drs. V. Hazelwood, H.
Kambic, A. Valdevit, and our clinical advisor Dr. M. Majsak for their
technical input and assistance.
Fig. 2. Typical clinical setup of the PiP system.