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Evaluation of an intelligent wheelchair system for older adults with cognitive impairments.

How TV, Wang RH, Mihailidis A - J Neuroeng Rehabil (2013)

Bottom Line: Measurements of safety and usability were taken and compared between the two phases.However, the objective performance (time to complete course) of users navigating their environment did not improve with the IWS.This study shows the efficacy of the IWS in performing with a potential environment of use, and benefiting members of its desired user population to increase safety and lower perceived demands of powered wheelchair driving.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto ON, Canada.

ABSTRACT

Background: Older adults are the most prevalent wheelchair users in Canada. Yet, cognitive impairments may prevent an older adult from being allowed to use a powered wheelchair due to safety and usability concerns. To address this issue, an add-on Intelligent Wheelchair System (IWS) was developed to help older adults with cognitive impairments drive a powered wheelchair safely and effectively. When attached to a powered wheelchair, the IWS adds a vision-based anti-collision feature that prevents the wheelchair from hitting obstacles and a navigation assistance feature that plays audio prompts to help users manoeuvre around obstacles.

Methods: A two stage evaluation was conducted to test the efficacy of the IWS. Stage One: Environment of Use - the IWS's anti-collision and navigation features were evaluated against objects found in a long-term care facility. Six different collision scenarios (wall, walker, cane, no object, moving and stationary person) and three different navigation scenarios (object on left, object on right, and no object) were performed. Signal detection theory was used to categorize the response of the system in each scenario. Stage Two: User Trials - single-subject research design was used to evaluate the impact of the IWS on older adults with cognitive impairment. Participants were asked to drive a powered wheelchair through a structured obstacle course in two phases: 1) with the IWS and 2) without the IWS. Measurements of safety and usability were taken and compared between the two phases. Visual analysis and phase averages were used to analyze the single-subject data.

Results: Stage One: The IWS performed correctly for all environmental anti-collision and navigation scenarios. Stage Two: Two participants completed the trials. The IWS was able to limit the number of collisions that occurred with a powered wheelchair and lower the perceived workload for driving a powered wheelchair. However, the objective performance (time to complete course) of users navigating their environment did not improve with the IWS.

Conclusions: This study shows the efficacy of the IWS in performing with a potential environment of use, and benefiting members of its desired user population to increase safety and lower perceived demands of powered wheelchair driving.

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Related in: MedlinePlus

Environment of use testing scenarios. Anti-collision and navigation are tested by driving the wheelchair towards different objects. A 3 m distance was set in order for the wheelchair to achieve a constant velocity of 0.16 m/s. For anti-collision testing: A) stationary objects on centerline; B) moving person that steps onto the centerline when wheelchair is within 700 mm of the person. For navigation testing: C) object on left of centerline; D) object on right of centerline.
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Figure 4: Environment of use testing scenarios. Anti-collision and navigation are tested by driving the wheelchair towards different objects. A 3 m distance was set in order for the wheelchair to achieve a constant velocity of 0.16 m/s. For anti-collision testing: A) stationary objects on centerline; B) moving person that steps onto the centerline when wheelchair is within 700 mm of the person. For navigation testing: C) object on left of centerline; D) object on right of centerline.

Mentions: To evaluate the IWS’s anti-collision feature, the IWS was mounted on a Pride Mobility™ Quantum 6000z powered wheelchair and driven towards six different object scenarios that would typically be found in a long-term care facility: 1) white wall pillar, 2) aluminum four-wheeled walker, 3) aluminum walking cane, 4) stationary person, 5) moving person, and 6) no object (to test for false detections). The wheelchair was driven from a distance of 3 m toward the objects to allow for a constant velocity of 0.16 m/s to be reached (Figure 4A). This velocity was chosen to allow for comparison with previous testing results [21]. Driving motion continued until the anti-collision feature stopped the wheelchair or the wheelchair hit the object. A threshold of 700 mm was set as the anti-collision stopping distance from the front of the sensor; this value was chosen to compare with previous testing results, and was inferred as a safe stopping distance with the camera mounted 300 mm behind the furthest forward point of the wheelchair (i.e. the footrests). For the moving person scenario, the person remained outside the field of view (FOV) of the camera until the camera came within 700 mm of the person (Figure 4B). At this time, the person would step into the FOV and stop in front of the wheelchair; this represented the worst case scenario of an object entering the FOV of the camera for the set threshold distance. The wheelchair was driven toward each object scenario 20 times. Both the response of the anti-collision feature and the stopping distance from the front of the sensor to the object were recorded.


Evaluation of an intelligent wheelchair system for older adults with cognitive impairments.

How TV, Wang RH, Mihailidis A - J Neuroeng Rehabil (2013)

Environment of use testing scenarios. Anti-collision and navigation are tested by driving the wheelchair towards different objects. A 3 m distance was set in order for the wheelchair to achieve a constant velocity of 0.16 m/s. For anti-collision testing: A) stationary objects on centerline; B) moving person that steps onto the centerline when wheelchair is within 700 mm of the person. For navigation testing: C) object on left of centerline; D) object on right of centerline.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750699&req=5

Figure 4: Environment of use testing scenarios. Anti-collision and navigation are tested by driving the wheelchair towards different objects. A 3 m distance was set in order for the wheelchair to achieve a constant velocity of 0.16 m/s. For anti-collision testing: A) stationary objects on centerline; B) moving person that steps onto the centerline when wheelchair is within 700 mm of the person. For navigation testing: C) object on left of centerline; D) object on right of centerline.
Mentions: To evaluate the IWS’s anti-collision feature, the IWS was mounted on a Pride Mobility™ Quantum 6000z powered wheelchair and driven towards six different object scenarios that would typically be found in a long-term care facility: 1) white wall pillar, 2) aluminum four-wheeled walker, 3) aluminum walking cane, 4) stationary person, 5) moving person, and 6) no object (to test for false detections). The wheelchair was driven from a distance of 3 m toward the objects to allow for a constant velocity of 0.16 m/s to be reached (Figure 4A). This velocity was chosen to allow for comparison with previous testing results [21]. Driving motion continued until the anti-collision feature stopped the wheelchair or the wheelchair hit the object. A threshold of 700 mm was set as the anti-collision stopping distance from the front of the sensor; this value was chosen to compare with previous testing results, and was inferred as a safe stopping distance with the camera mounted 300 mm behind the furthest forward point of the wheelchair (i.e. the footrests). For the moving person scenario, the person remained outside the field of view (FOV) of the camera until the camera came within 700 mm of the person (Figure 4B). At this time, the person would step into the FOV and stop in front of the wheelchair; this represented the worst case scenario of an object entering the FOV of the camera for the set threshold distance. The wheelchair was driven toward each object scenario 20 times. Both the response of the anti-collision feature and the stopping distance from the front of the sensor to the object were recorded.

Bottom Line: Measurements of safety and usability were taken and compared between the two phases.However, the objective performance (time to complete course) of users navigating their environment did not improve with the IWS.This study shows the efficacy of the IWS in performing with a potential environment of use, and benefiting members of its desired user population to increase safety and lower perceived demands of powered wheelchair driving.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto ON, Canada.

ABSTRACT

Background: Older adults are the most prevalent wheelchair users in Canada. Yet, cognitive impairments may prevent an older adult from being allowed to use a powered wheelchair due to safety and usability concerns. To address this issue, an add-on Intelligent Wheelchair System (IWS) was developed to help older adults with cognitive impairments drive a powered wheelchair safely and effectively. When attached to a powered wheelchair, the IWS adds a vision-based anti-collision feature that prevents the wheelchair from hitting obstacles and a navigation assistance feature that plays audio prompts to help users manoeuvre around obstacles.

Methods: A two stage evaluation was conducted to test the efficacy of the IWS. Stage One: Environment of Use - the IWS's anti-collision and navigation features were evaluated against objects found in a long-term care facility. Six different collision scenarios (wall, walker, cane, no object, moving and stationary person) and three different navigation scenarios (object on left, object on right, and no object) were performed. Signal detection theory was used to categorize the response of the system in each scenario. Stage Two: User Trials - single-subject research design was used to evaluate the impact of the IWS on older adults with cognitive impairment. Participants were asked to drive a powered wheelchair through a structured obstacle course in two phases: 1) with the IWS and 2) without the IWS. Measurements of safety and usability were taken and compared between the two phases. Visual analysis and phase averages were used to analyze the single-subject data.

Results: Stage One: The IWS performed correctly for all environmental anti-collision and navigation scenarios. Stage Two: Two participants completed the trials. The IWS was able to limit the number of collisions that occurred with a powered wheelchair and lower the perceived workload for driving a powered wheelchair. However, the objective performance (time to complete course) of users navigating their environment did not improve with the IWS.

Conclusions: This study shows the efficacy of the IWS in performing with a potential environment of use, and benefiting members of its desired user population to increase safety and lower perceived demands of powered wheelchair driving.

Show MeSH
Related in: MedlinePlus