Transcript Powered Mobility

Powered Mobility
Overview
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Introduction
Types of powered mobility
Outcomes
Components of a powered wheelchair
Future designs
The use of powered mobility?
• Means of independent mobility for people
who may not be able to self propel a
manual wheelchair.
• Not limited to those who cannot manually
self propel a manual wheelchair.
• Not limited to those who cannot walk
(social, cognitive, and functional benefits)
Why use it?
• Mobility is essential for self-care, work, school, play or
leisure
• Intentional movement and active exploration is critical in
the development of a child’s knowledge concerning his
body, his movement and his environment
(Lewis B.J.)
• Strong evidence that social integration leads to reduced
mortality risks, and to a better state of mental health...
social isolation and non-supportive social interactions
can result in lower immune function
(Seeman, 1999)
Types of powered mobility
• Scooters
• Add-on Power devices
• Power wheelchairs
Mobility Scooters
Similar to powered wheelchairs but
have handlebars to steer
The seat usually swivels to facilitate
easy access
Tend to be used for individuals who
have systemic or whole-body
disabling conditions such as coronary
or lung issues or some forms of
arthritis.
Add-on Power devices
Add-on Power devices provide motorised power to
the standard manual wheelchair
Some are designed either to:
• assist the attendant push the wheelchair
• assist the user to self-propel the wheelchair
manually
• or to convert the manual chair into a
powered wheelchair controlled by a joystick.
A key feature is that they can be easily attached to
and removed from the manual wheelchair
Motor and battery built
into the hub of the wheel
Powered wheelchair
• Rear wheel, Mid wheel and Front
wheel drive versions
• Indoor and outdoor
• Typically controlled by a joystick
but there are various other inputs
• Tilt-in-space and reclining
systems are available
Positive outcomes
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Increased functional ability
Greater social inclusion
Access to education and employment
Reduced dependence on carers
Reduced fatigue
Better performance & efficiency
Challenges...?
• Access adaptations such as wheelchair spaces
on public transport and wheelchair lifts are
frequently designed around a typical manual
wheelchairs
• Because of the weight and size they typically
cannot be self propelled by the user
• Require daily charging
• Generally non-foldable and requiring tie-downs
in a van for transportation
• Expensive
History
• 1950s - Everest & Jennings (USA) developed the first
powered wheelchair
• 1980s - wheelchairs now were microprocessor-controlled
and provided customization of controls to meet the need
• 1980-90s - the revolution in powered wheelchair design
with various new controls, styles, range in distance,
suspension, maneuverability, and seating options
Major System Components
An input device is used by the user to
specify velocity and directional when
driving or to navigate within a menu
displayed on the controller
Various types
– Proportional (joystick).
– Non-proportional (switch inputs, sip and
puff).
• Scan-control can be used to reduce the number
of switches required
Proportional
Standard
joystick
Finger
joystick
Mini
joystick
Non-Proportional
Switch
Sip and puff
Switch
array
Switch
scanner
• Microprocessor-based
• The controller translates signal from the input
device to a velocity and direction command for
the power controller
• If provides feedback to the user via the display
• Monitors performance of wheelchair
• Contains the custom adjustable control
parameters of the chair
What controller parameters (or
adjustments) do you think may be
adjusted for a user?
Most common adjustments
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Max speed
Acceleration
Deceleration
Turning speed
Turning acceleration
Turning deceleration
• The battery provides the energy for the
power wheelchair to drive
• They are connected to the Power controller
• 24V (commonly 2 x 12V)
• Lead-Acid / Deep Cycle Gel Cell
Battery Protection
• To protect the batteries and
the system cables from
external short circuits a
thermal circuit is installed
• If the battery Voltage falls
below 21V damage to the
battery may occur. The
controller alerts the user of
low voltage condition.
Typically controller reduces
the performance of the
power chair.
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Why are the use of “gel-cell”
batteries an important safety
issue?
“gel-cell” batteries are sealed and
so no acid will leak in the event
that the chair falls over
• The Power Controller sends the power to
the motors and to the other modules
• It controls the electrical energy delivered to
the motors.
• The motors control the power
wheelchair speed and direction
• 24V AC or DC
• resistance of different motor types
varies typically between 20 and 350
mΩ
• Current rating 60 – 120 A
• Fail-safe electro-magnetic parkbrakes
attached to the motors prevent the
power chair moving when it is not
actively driven or when the power is
turned off.
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How is a wheelchair with two
motors steered?
Motors rotate wheels at different
speeds
The turning angle is relative to the
difference
Modern power chairs now have the
options to control a PC, mobile phone
or aspects of the environment
Could this be the future?
electric drive motor with gyroscopic
sensors to help the driver to move
Summary
• Mobility is essential for quality of life
• Powered mobility provides a means of
independence
• There are various types of powered
mobility devices to suit a user needs
• Enables the user to have control of their
environment
Bibliography
1. Albert M. Cook, Susan M. Hussey 2002 Assistive technologies: principles
and practice
2. Learner J, Beverly J, 2008, Learning Disabilities and Related Mild
Disabilities
3. Chan J, Davey C, Bath Institute of Medical Engineer, Buyers Guide Add
on power devices for manual wheelchairs Aug 2008
4. D.A. Hobson,September 1999, viewed 10th May 2010
http://www.wheelchairnet.org/
5. DX System Manual, Dynamic Controls,
http://www.dynamiccontrols.com/index.cfm/1,81,html
6. Wikipedia, Mobility scooter, viewed 10th May 2010
<http://en.wikipedia.org/wiki/Mobility_scooter>