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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

Hardware diagram of the Intelligent Wheelchair System (IWS) when attached to a powered wheelchair.
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Figure 1: Hardware diagram of the Intelligent Wheelchair System (IWS) when attached to a powered wheelchair.

Mentions: Figure 1 shows a block diagram of the IWS. A sensor is used to detect the environment in front of the wheelchair. This environmental information is then sent to an Onboard Computing Unit (OCU) for processing and analysis. The OCU determines the distance of obstacles from the front of the powered wheelchair and the free space surrounding those obstacles. If an obstacle is too close to the powered wheelchair the OCU will issue a prevention command to the joystickDCLM (Direction Control Logic Module). From this, the joystickDCLM will prevent any further wheelchair movement towards the obstacle. The joystickDCLM is situated between the user’s input device (i.e. joystick) and the wheelchair’s controller; it has the ability to prevent unsafe user inputs from reaching the wheelchair’s motors. When the wheelchair remains stopped by an obstacle for a certain period of time (~2 seconds), the OCU will play an audio prompt to help the user navigate into free space surrounding the obstacle (e.g., “try turning left”, “try turning right”). This audio prompt is repeated every five seconds if the wheelchair continues to remain stopped.


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

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

Hardware diagram of the Intelligent Wheelchair System (IWS) when attached to a powered wheelchair.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Hardware diagram of the Intelligent Wheelchair System (IWS) when attached to a powered wheelchair.
Mentions: Figure 1 shows a block diagram of the IWS. A sensor is used to detect the environment in front of the wheelchair. This environmental information is then sent to an Onboard Computing Unit (OCU) for processing and analysis. The OCU determines the distance of obstacles from the front of the powered wheelchair and the free space surrounding those obstacles. If an obstacle is too close to the powered wheelchair the OCU will issue a prevention command to the joystickDCLM (Direction Control Logic Module). From this, the joystickDCLM will prevent any further wheelchair movement towards the obstacle. The joystickDCLM is situated between the user’s input device (i.e. joystick) and the wheelchair’s controller; it has the ability to prevent unsafe user inputs from reaching the wheelchair’s motors. When the wheelchair remains stopped by an obstacle for a certain period of time (~2 seconds), the OCU will play an audio prompt to help the user navigate into free space surrounding the obstacle (e.g., “try turning left”, “try turning right”). This audio prompt is repeated every five seconds if the wheelchair continues to remain stopped.

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