A SMARTPHONE APPLICATION FOR IMPROVING POWERED SEAT FUNCTIONS
USAGE
Yu-Kuang Wu, MS PT1,2, Brandon Daveler, BS1,2, Hsin-Yi Liu, MS PT1,2, Josh Brown, BS1,2, Annmarie
Kelleher, MS OTR/L1,2, Hongwu Wang, PhD1,2, Rory A. Cooper, PhD1,2
1
Department of Rehabilitation Sciences and Technology, School of Health and Rehabilitation
Sciences, University of Pittsburgh
2
Human Engineering Research Laboratories, Department of Veterans Affairs Pittsburgh
Healthcare System Pittsburgh, PA, USA
Background
Introduction and Rationale
Powered wheelchairs with powered seat functions are prescribed for wheelchair users
who are unable to adjust their postures or manage their seating pressure independently because
of motor and/ or sensory impairments. [1] The powered seat functions can (1) provide users with
dynamic postural support, (2) help them reposition and redistribute the seating pressure, (3)
provide management of secondary complications and (4) improve driving safety and users’ daily
function. [1-3] However, going through the activities of daily living while having to
appropriately utilize the powered seat functions can be overwhelming for a wheelchair user. For
this reaseon, we have been developing and testing the Virtual Seating Coach (VSC) [4, 5], which
is a tailored reminder system to facilitate powered wheelchair users to utilize powered seating
functions based on clinical recommendations. The concept is that the VSC program compares
powered seat function usage data with clinician's recommendations and provides appropriate
reminders to the users. The results in our pilot study have shown that VSC increased subjects'
compliance of powered seat functions usage, such as increasing the frequency of performing
pressure relief. [6] The preliminary findings encourage us to develop an easily installed VSC
system to increase the number of individuals who can benefit from this application, since our
current VSC system requires a complicated and time-consuming process of sensor installation. In
addition, with the increasing number of smartphone users, converting VSC program into a userfriendly smartphone app could be a good idea in terms of widespreading our application.
Methods
Project description
The purpose of this project is to develop a smartphone based VSC by using
accelerometers to measure the powered seat function usage. Also, one usability test has been
conducting to understand the usability of our smartphone VSC application.
Procedures
Hardware
Four accelerometers are placed on the seat pan, backrest, legrest, and the wheelchair base to
detect the tilt, recline, legrest, and wheelchair base angles. The accelerometers’ signal is sent to
an Android smartphone via the USB cable after analog to digital conversion by a microcontroller.
Software
Two applications are running in the smartphone. One application keeps requesting the
microcontroller board to send the accelerometer data to the phone for data collection, while
another application is displaying the information on the smartphone screen.
Usability test
In the usability test, we installed our smartphone VSC system on users’ personal powered
wheelchair. After a series of hand on training, we asked these users to answer a questionnaire
with respect to the usability of our system.
RESULTS
Figure 1A shows the interface displaying the angles for seat
tilt, backrest recline, legrest elevation and the position of the
wheelchair base. Figure 1B indicates how the application instructs
users to adjust their powered seat function.
Figure 1. Screenshots of smartphone
VSC application
User Control
4.5
Scale
4
Figure 2.
3.5One part of preliminary results from
usability study.
3
0: Totally Disagree
5: Totally Agree
Figure 2 shows one part of preliminary results from the usability data of five powered wheelchair
users. As can be seen, most users found that the VSC application is easy to learn and use.
However, they also reported that it is hard to navigate the application when they got powered
seat function usage warning. This might be due to the fact that a warning message appears as a
text message, which is easily ignored.
DISCUSSION
CONCLUSION
The goal of the smartphone-based VSC system is to implement our seating coach on a
user-friendly mobile app form that requires no additional hardware modifications of the powered
wheelchair. We are currently evaluating our prototype by gathering the feedback from the endusers via conducting the usability study.
Significance and Importance
The availability of the VSC app will promote access to this educational tool by users and
clinicians and may further advocate the importance of powered seat functions and proper user
training.
References
1.
Trefler E, S.M., State of The Science White Paper on Seating for Postural Control. 2001.
2.
Lange, M., Positioning: it's all in the angles. Advance for Occupational Therapy
Practitioners, 2006.
3.
Dicianno, B.E., et al., RESNA position on the application of tilt, recline, and elevating
legrests for wheelchairs. Assist Technol, 2009. 21(1): p. 13-22; quiz 24.
4.
Ding, D., et al., Virtual coach technology for supporting self-care. Phys Med Rehabil
Clin N Am, 2010. 21(1): p. 179-94.
5.
Liu., H.-y., et al., Seating virtual coach: A smart reminder for power seat function usage.
Technology and Diability, 2010. 22: p. 53-60.
6.
Liu, H.-y., et al., Case Study: Pilot Test of Virtual Seating Coach Evaluated by Power
Seat Function Users., in Rehabilitation Engineering and Assistive Technology Society of
North America Conference, Baltimore, MD. 2012.