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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

Average stopping distances from the obstacle to the sensor. Dashed line indicates set threshold distance (700 mm). Results for the previous iteration of the IWS are shown in blue1, and the current IWS are shown in green. Distances that are closer to the threshold indicate a more accurate stopping distance. Error bars show the standard deviation of stopping distances.
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Figure 6: Average stopping distances from the obstacle to the sensor. Dashed line indicates set threshold distance (700 mm). Results for the previous iteration of the IWS are shown in blue1, and the current IWS are shown in green. Distances that are closer to the threshold indicate a more accurate stopping distance. Error bars show the standard deviation of stopping distances.

Mentions: The IWS performed successfully in all anti-collision test conditions. Table 3 compares the anti-collision performance of our previous system [21] and the IWS. Two misses occurred in both the wall and cane scenarios with the previous system. Figure 6 summarizes the average stopping from the object to the sensora. In all but one condition, the IWS had a closer stopping average to the set threshold than the previous system. Only the moving person scenario was on average 60 mm farther from the threshold than the previous system. For all conditions the IWS had smaller standard deviations in stopping distances (ranging from 16 - 37 mm) than the previous system (ranging from 78 -108 mm).


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

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

Average stopping distances from the obstacle to the sensor. Dashed line indicates set threshold distance (700 mm). Results for the previous iteration of the IWS are shown in blue1, and the current IWS are shown in green. Distances that are closer to the threshold indicate a more accurate stopping distance. Error bars show the standard deviation of stopping distances.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Average stopping distances from the obstacle to the sensor. Dashed line indicates set threshold distance (700 mm). Results for the previous iteration of the IWS are shown in blue1, and the current IWS are shown in green. Distances that are closer to the threshold indicate a more accurate stopping distance. Error bars show the standard deviation of stopping distances.
Mentions: The IWS performed successfully in all anti-collision test conditions. Table 3 compares the anti-collision performance of our previous system [21] and the IWS. Two misses occurred in both the wall and cane scenarios with the previous system. Figure 6 summarizes the average stopping from the object to the sensora. In all but one condition, the IWS had a closer stopping average to the set threshold than the previous system. Only the moving person scenario was on average 60 mm farther from the threshold than the previous system. For all conditions the IWS had smaller standard deviations in stopping distances (ranging from 16 - 37 mm) than the previous system (ranging from 78 -108 mm).

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