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Utilization of Ultrasound Sensors
for Anti-Collision
Systems of Powered Wheelchairs
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Outline
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Problems and Rationale
Purpose and Specific Aims
Materials and Methods
Results and Discussion
Conclusions
Future work
Reference
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 Problems
and Rationale
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Problems and Rationale
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The smart wheelchair systems designed currently
are too complex
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A commercial product within the near future
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Residences or long-term care facilities
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Problems and Rationale
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Studies have estimated 20%–30% of such falls
will result in injury
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5%–10% Result in a fracture or hip fracture
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The activity of most cases with hip fractures
will not be restored
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Up to 40% will die from complications within
six months of sustaining hip fracture
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 Purpose
and Specific Aims
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Purpose and Specific Aims
 Purpose
 Determine whether ultrasound sensors are
suitable for an anti-collision system
 Specific Aims
 Minimize the overall complexity of the resulting
system to make real world implementation
feasible.
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 Materials
and Methods
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Materials and Methods
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Preliminary investigation
This prediction was tested using three spheres with diameters of 0.1, 0.2, and 0.3 m.
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Materials and Methods
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The visibility of the following objects was
tested:
1) Simulated cane or table leg
2) Simulated human leg
3) Facing perpendicular to a wall
4) Wall at various angles
5) Table top
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Materials and Methods
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We assumed objects in the surroundings
were not moving
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Allowing for people in the environment to be
moving toward the chair would require the
stopping distance to be reduced.
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Materials and Methods
Simulated Cane or Table Leg
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A 1.2-m long steel tube with 0.025-m
diameter was used to simulate a cane or
table leg
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Materials and Methods
Simulated Human Leg
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A 1-m cylinder with 0.10-m diameter was
loosely covered in cloth and was used to
simulate a human leg
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Materials and Methods
Wall
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the ultrasound sensors. Painted dry-wall,
concrete, wood as well as glass panes were
tested
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Materials and Methods
Table Top
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Sensor 0.5 m away from the center of the
table top
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Sensor 0.5 m away from a point 0.15 m
from the edge of the table top
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 Results
and Discussion
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Results and Discussion
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Simulated Cane or Table Leg
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Results and Discussion
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Simulated Human Leg
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Results and Discussion
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Wall Surfaces
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Moving Away From a Wall,Perpendicular
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Approaching a Wall at Various Angles
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Results and Discussion
 Ultrasound
sensors do have the
ability to resolve distances in the
range of interest
 That
no hard objects can be found in
zones on either side of the wheelchair
without causing “false stops"
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Results and Discussion
Sensors on Front and Back of the Wheelchair
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Results and Discussion
Sensors on the Side of the Wheelchair
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One drawback of this is that it now
becomes considerably harder to
navigate through a doorway
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wheelchair if they come within 0.05 m of
a wall, then we lose 0.1 m of the 0.3 m
original clearance (0.9-m-wide doorway
and 0.6-m–wide wheelchair)
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Results and Discussion
Other Obstacles
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The ultrasound sensor was its marked
inability to detect table edges particularly
for a table top with a table cloth
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 Conclusions
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Conclusions
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Ultrasound sensors do have the ability to
resolve distances in the range of interest
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if we consider overall “sensing time” using
EERUF does not really solve our time delay
problem. For these reasons, ultrasound sensors
by themselves, are not suitable for use with
anti-collision systems of a powered wheelchair.
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Future work
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The suitability of other sensor systems
 EP: infrared sensors, active light systems,
stereo vision systems, and others
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The possibility of creating a modified
environment in the home or long-term
care facility
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 Reference
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Reference
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Thank you for your attention
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