2 research outputs found

    TOWARDS MONITORING WHEELCHAIR PROPULSION IN NATURAL ENVIRONMENT USING WEARABLE SENSORS

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    Due to lower limb paralysis, individuals with spinal cord injury (SCI) rely on their upper limbs for activities of daily living (ADLs) and wheelchair propulsion (WP). Previous research has found that specific biomechanical parameters of WP are associated with risk of UE pain and injury. However, the repetitiveness and quality of upper limb movements during WP are unclear. Recently, wearable sensors have been used to collect mobility characteristics of wheelchair users, but little research has looked into using them to monitor the quality of UE movements for WP in the natural environment. The purpose of this thesis was to develop and evaluate a WP monitoring device that can monitor wheelchair users’ activities, and propulsion parameters in the natural environment. This thesis is organized into three studies. The first study aims to develop activity classifiers that can distinguish WP episodes from a range of ADLs. Two classifying models were built using a Machine Learning (ML) technique. The model that yielded the highest accuracy showed an overall accuracy of 88.0%. Time spent on each activity was estimated based on the classifiers, and compared with the video observation. Percentage of difference between the criterion and estimated time ranged from 2.2% to 11.6%. The second study aims to estimate temporal parameters of WP, including the stroke number (SN) and push frequency (PF), using wearable sensors. The estimated SN and PF were compared with the criterion measures using the mean absolute errors (MAE) and mean absolute percentage of error (MAPE). Intraclass Correlation Coefficients were calculated to assess the agreement. The accelerometer placed on the upper arm yielded the highest accuracy with the MAPE of 8.0% for SN and 12.9% for PF. The third study aims to estimate wheelchair propulsion forces. Propulsion forces were estimated from the accelerometer placed on the upper arm using a bagging regression technique. The estimated forces were compared with the criterion. Mean absolute errors (MAE), mean absolute percentage of error (MAPE), were calculated. The results showed an overall MAPE of 17.9%. Intraclass Correlation Coefficients and Bland-Altman plots were used to assess the agreement between the criterion and the estimated force

    Understanding Route Choices for Wheelchair Navigation

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    Purpose: To validate a personalized routing technique with wheelchair users, understand their route choices and acquire their feedback on the necessity of wheelchair navigation and the importance of personalized routes. Method: A routing technique using a weighting method, called Absolute Restriction Method (ARM), was employed to compute personalized routes based on users' routing preferences. The evaluation involves five manual wheelchair users. The study protocol consists of three sessions: pre-activity, activity and post-activity sessions. The evaluation included a comparison between personalized routes and shortest feasible routes, in terms of route characteristics and users' ratings of important parameters. Results: Subjects travelled a 14.64% longer distance along the personalized routes than the shortest feasible routes. However, all personalized routes had better path quality (slope and surface condition) than the shortest feasible routes. Four out of five subjects rated the parameters they deemed most important higher for the personalized route than for the shortest feasible route. Conclusions: The study confirmed that the shortest route criterion is not always suitable for individuals with mobility impairments. Personalized routes that take into account individual characteristics, route preferences and environmental characteristics are a promising solution to lessen the difficulties that manual wheelchair users face when navigating unfamiliar environments.Implications for RehabilitationWheelchair users indicate the importance of personalized routes for individuals with mobility impairments.In regard to evaluation results, although subjects travelled 14.64% more distances in average along the personalized routes than the shortest feasible routes, they rated the personalized routes better path quality and less effort to travel
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