Classification of wheelchair pressure relief maneuvers using changes in center of pressure and weight on the seat.

BACKGROUND: Pressure injuries from prolonged sitting are a significant problem for wheelchair users incurring high costs in healthcare expenditures and reducing quality-of-life. There is a need to improve pressure relief training and adherence in a variety of settings. OBJECTIVE: To identify effective common wheelchair pressure relief (PR) manoeuvres based on changes to users' seated centre of pressure (CoP) and seated weight. PARTICIPANTS: 20 individuals who use manual wheelchairs as their primary means of mobility. METHODS: Participants performed 5 types of PR including seated push-ups, leftward, rightward, forward, and backward leans-while sitting in a wheelchair equipped with a custom instrumented seat pan support. Data were analysed using both clustering and decision tree approaches to identify types of PR. RESULTS: Both clustering and decision tree approaches were able to identify and classify PR though neither could accurately distinguish between forward and backward PR. CONCLUSION: Changes in the centre of pressure and the total weight on the wheelchair's seat can be used to automatically characterise type, amplitude and duration of pressure relief manoeuvres. Building such a classification and quality assessment scheme into an algorithm could enable a virtual coaching system to track users' pressure relief behaviour and make suggestions to improve adherence with clinical recommendations.IMPLICATIONS FOR REHABILITATIONMultiple bending beam load cells can be used to measure wheelchair users' seated centre of pressure independent of type of cushion used.Both cluster analysis and decision tree algorithms can classify commonly practiced pressure reliefs by measuring changes to the centre of pressure and total weight on the wheelchair's seat.The combination of force sensing for centre of pressure determination and either algorithm could serve as the basis for an application to coach wheelchair users to do effective pressure reliefs.

Power seat function usage and wheelchair discomfort for power wheelchair users.

OBJECTIVES: To investigate correlations between power seat functions (PSFs) usage and wheelchair discomfort. DESIGN: Quasi-experimental design: Time series design. SETTING: In-home trial in participants' home/community. PARTICIPANTS: Thirteen power wheelchair users who independently used power wheelchairs equipped with PSFs as their primary means of mobility. MAIN OUTCOME MEASURES: PSF usage variables include the frequency of performing repositioning and using PSFs (tilt, recline, legrests and seat elevation), wheelchair occupancy, and driving distance. The Tool for Assessing Wheelchair disComfort (TAWC) were used to evaluate general discomfort and discomfort intensity. RESULTS: Spearman correlation coefficient showed that the frequency of using tilt, recline, and legrest is significantly correlated with discomfort intensity. Multiple regression analysis with backward stepwise indicated that these functions can explain 43.8% of the variance (R2 = .438, F(3,33) = 8.588, P < 0.01) in the discomfort intensity score. The best-first decision tree shows that the frequency of using the legrest function was the top node, followed by recline and tilt functions. The overall accuracy of prediction with ten-fold cross validation for discomfort intensity was 79.4%. CONCLUSIONS: For people who used power wheelchairs equipped with PSFs, correlation analysis and regression modeling provided evidence from the quantitative data that increasing the frequency of using PSFs may decrease wheelchair discomfort. Future studies should include interventions to encourage people to use their PSFs appropriately.

Consumer Feedback to Steer the Future of Assistive Technology Research and Development: A Pilot Study.

Objective: The overall objective of this project was to identify consumers' opinions of their needs and wants related to assistive technology (AT) in a systematic and quantitative manner via a questionnaire that can be used to validate existing and establish new research priorities. Methods: This pilot study describes questionnaire development, online implementation, and revisions considered to the questionnaire in preparation for conducting a nationwide survey. Data from a sample (N = 112) are presented. The pilot study was critical to refine the questions and ensure that meaningful information was being collected. Results: It was identified that revisions were warranted to provide more structure and allow for consumers to prioritize AT research efforts. Conclusion: The questionnaire results, although positively in favor of many of the technologies presented, are inconclusive to identify generalizable research priorities, thus expansion to a nationwide population is warranted.

Further Development of a Robotic-Assisted Transfer Device.

Background: The task of performing transfers, such as from a wheelchair to a bed, has a high risk of injury to both the caregiver and the person being transferred. Although mechanical transfer devices can reduce these risks, these devices are not meant for use in the community and they still place strain on the caregiver when used. Purpose: The aim of this study is to describe feedback gathered from focus groups of potential users of the Robotic-Assisted Transfer Device (RATD) and describe design changes aimed at preparing the device for the next step in the development process. Method: The RATD was transferred to a newer electric-powered wheelchair (EPW), key components were redesigned, and the control program was updated to increase the safety of the device. Two focus groups, one consisting of people with disabilities and the other consisting of clinicians and caregivers, were conducted to gather feedback from potential users. Results: Error checking, safety zones, a motor brake, and a new track helped increase the safety of the device. Sixty-three percent of the people with disabilities and 83% of caregivers surveyed said they would use the device. Conclusions: The results from the focus groups were positive and the design changes were successful, but more development is needed before the RATD can be marketed.

Performance Evaluation of a Mobile Touchscreen Interface for Assistive Robotic Manipulators: A Pilot Study.

Background: Assistive robotic manipulators (ARMs) have been developed to provide enhanced assistance and independence in performance of daily activities among people with spinal cord injury when a caregiver is not on site. However, the current commercial ARM user interfaces (UIs) may be difficult to learn and control. A touchscreen mobile UI was developed to overcome these challenges. Objective: The object of this study was to evaluate the performance between 2 ARM UIs, touchscreen and the original joystick, using an ARM evaluation tool (ARMET). Methods: This is a pilot study of people with upper extremity impairments (N = 8). Participants were trained on 2 UIs, and then they chose one to use when performing 3 tasks on the ARMET: flipping a toggle switch, pushing down a door handle, and turning a knob. Task completion time, mean velocity, and open interviews were the main outcome measurements. Results: Among 8 novice participants, 7 chose the touchscreen UI and 1 chose the joystick UI. All participants could complete the ARMET tasks independently. Use of the touchscreen UI resulted in enhanced ARMET performance (higher mean moving speed and faster task completion). Conclusions: Mobile ARM UIs demonstrated easier learning experience, less physical effort, and better ARMET performance. The improved performance, the accessibility, and lower physical effort suggested that the touchscreen UI might be an efficient tool for the ARM users.

Task-Oriented Performance Evaluation for Assistive Robotic Manipulators: A Pilot Study.

OBJECTIVE: The objectives of this study were to evaluate the performance of commercially available assistive robotic manipulators (ARMs) user interfaces and to investigate the concurrent validity and sensitivity to change with task-oriented performance evaluation tools (TO-PETs) for ARMs. DESIGN: This was a nonblinded randomized controlled study with power-wheelchair users with upper-extremity impairments (N = 10). Participants were trained to use 2 ARMs with their respective original user interfaces (keypad and joystick) and evaluated the performance using TO-PET and the adapted Wolf Motor Function Test (WMFT-ARM). Task completion time, ISO 9241-9 throughput, trajectory parameters, NASA-TLX, and questionnaires were the main outcome measurements. Concurrent validity and sensitivity were evaluated. RESULTS: Statistical differences were found in ISO 9241-9 throughput between the 2 user interfaces for the single motion tasks and WMFT-ARM. However, there was no statistical difference found on the self-reported perceived workload and ease of use. Moderate to high correlation was found between the TO-PET and WMFT-ARM (P < 0.001). The TO-PET demonstrated higher Cohen d (0.910-1.085) than the WMFT-ARM. CONCLUSIONS: The findings of this study provide a preliminary comparison between 2 commercial ARMs with their different user interfaces among novice ARM users. Recommendations for training and evaluation were revealed.

Evaluating the usability of a smartphone virtual seating coach application for powered wheelchair users.

The aim of the smartphone virtual seating coach (SVSC) was to provide a personalized reminder/warning system to encourage powered wheelchair users to use their powered seating functions (PSFs) as clinically recommended. This study evaluated the usability of the SVSC system by gathering feedback from five powered wheelchair users and five rehabilitation professionals through questionnaires and interviews. The results indicated that clear and understandable instructions to adjust the PSFs are the most important requirement for SVSC application. The instructions must be intuitive, could benefit from animations or indications of PSFs control buttons so powered wheelchair users can adjust their PSFs immediately and appropriately.

Estimation of Energy Expenditure for Wheelchair Users Using a Physical Activity Monitoring System.

OBJECTIVE: To develop and evaluate energy expenditure (EE) estimation models for a physical activity monitoring system (PAMS) in manual wheelchair users with spinal cord injury (SCI). DESIGN: Cross-sectional study. SETTING: University-based laboratory environment, a semistructured environment at the National Veterans Wheelchair Games, and the participants' home environments. PARTICIPANTS: Volunteer sample of manual wheelchair users with SCI (N=45). INTERVENTION: Participants were asked to perform 10 physical activities (PAs) of various intensities from a list. The PAMS consists of a gyroscope-based wheel rotation monitor (G-WRM) and an accelerometer device worn on the upper arm or on the wrist. Criterion EE using a portable metabolic cart and raw sensor data from PAMS were collected during each of these activities. MAIN OUTCOME MEASURES: Estimated EE using custom models for manual wheelchair users based on either the G-WRM and arm accelerometer (PAMS-Arm) or the G-WRM and wrist accelerometer (PAMS-Wrist). RESULTS: EE estimation performance for the PAMS-Arm (average error ± SD: -9.82%±37.03%) and PAMS-Wrist (-5.65%±32.61%) on the validation dataset indicated that both PAMS-Arm and PAMS-Wrist were able to estimate EE for a range of PAs with <10% error. Moderate to high intraclass correlation coefficients (ICCs) indicated that the EE estimated by PAMS-Arm (ICC3,1=.82, P<.05) and PAMS-Wrist (ICC3,1=.89, P<.05) are consistent with the criterion EE. CONCLUSIONS: Availability of PA monitors can assist wheelchair users to track PA levels, leading toward a healthier lifestyle. The new models we developed can estimate PA levels in manual wheelchair users with SCI in laboratory and community settings.

Detection of physical activities using a physical activity monitor system for wheelchair users.

Availability of physical activity monitors for wheelchair users can potentially assist these individuals to track regular physical activity (PA), which in turn could lead to a healthier and more active lifestyle. Therefore, the aim of this study was to develop and validate algorithms for a physical activity monitoring system (PAMS) to detect wheelchair based activities. The PAMS consists of a gyroscope based wheel rotation monitor (G-WRM) and an accelerometer device (wocket) worn on the upper arm or on the wrist. A total of 45 persons with spinal cord injury took part in the study, which was performed in a structured university-based laboratory environment, a semi-structured environment at the National Veterans Wheelchair Games, and in the participants' home environments. Participants performed at least ten PAs, other than resting, taken from a list of PAs. The classification performance for the best classifiers on the testing dataset for PAMS-Arm (G-WRM and wocket on upper arm) and PAMS-Wrist (G-WRM and wocket on wrist) was 89.26% and 88.47%, respectively. The outcomes of this study indicate that multi-modal information from the PAMS can help detect various types of wheelchair-based activities in structured laboratory, semi-structured organizational, and unstructured home environments.

Stability analysis of electrical powered wheelchair-mounted robotic-assisted transfer device.

The ability of people with disabilities to live in their homes and communities with maximal independence often hinges, at least in part, on their ability to transfer or be transferred by an assistant. Because of limited resources and the expense of personal care, robotic transfer assistance devices will likely be in great demand. An easy-to-use system for assisting with transfers, attachable to electrical powered wheelchairs (EPWs) and readily transportable, could have a significant positive effect on the quality of life of people with disabilities. We investigated the stability of our newly developed Strong Arm, which is attached and integrated with an EPW to assist with transfers. The stability of the system was analyzed and verified by experiments applying different loads and using different system configurations. The model predicted the distributions of the system's center of mass very well compared with the experimental results. When real transfers were conducted with 50 and 75 kg loads and an 83.25 kg dummy, the current Strong Arm could transfer all weights safely without tip-over. Our modeling accurately predicts the stability of the system and is suitable for developing better control algorithms to enhance the safety of the device.

An interview study for developing a user guide for powered seating function usage.

PURPOSE: Powered seating functions (PSFs) provide powered wheelchair users an independent means to adjust posture dynamically. To facilitate the best use of PSFs in daily living, we conducted this structured interview study to develop a preliminary user guide to provide "take-home" information to powered wheelchair users. METHOD: An internally developed questionnaire to assess clinical recommendations of PSF usage was administered in an interview format to clinical seating and mobility specialists. A qualitative analysis was applied to codify the recommendations, and the findings were transformed into a PSF user guide. RESULTS: Specific but varied seating positions and temporal indications were recommended for performing pressure relief positioning. For several activities, appropriate seating positions should be determined according to the immediate physical condition of the user and/or the environmental settings. CONCLUSION: The methods and positions of using PSFs should be determined with consideration for individual preferences, physical condition, environmental setting, and desired tasks after thorough clinical seating assessments. Precautions about positioning and driving safety, and the importance of discussing with clinicians are emphasized in the user guide. This PSF user guide will be updated after more scientific evidence accumulates and be structurally evaluated for its face and content validity in the future.

Evaluation of scooters using ANSI/RESNA standards.

To date, only one research study has evaluated how scooters respond to static and dynamic stability. However, no other studies have evaluated how scooters respond to adverse conditions and how they perform in all standard tests. A selection of 12 three-wheeled scooters was tested according to American National Standards Institute/Rehabilitation Engineering and Assistive Technology Society of North America (ANSI/ RESNA) wheelchair standards. Scooter models included the Victory, Gogo, Golden Companion (GC) I, and GC II. Victory and GC II were the most stable scooters. The Gogo scooters were the least dynamically stable. Five scooters (3 Gogo, 1 GC I, 1 GC II) failed the environmental condition tests. All GC I and II scooters failed parts of the power and control system tests. All scooters passed static and impact tests; however, all Gogo scooters and one GC II scooter had structural or motor failure during durability tests. The scooter models' survival life ranged from 62,512 to 1,178,230 cycles out of the 400,000 needed to pass the test. Tiller failures (typically tiller tube snapping) occurred with an average of 1,483 N force applied to the tiller structure. Our results indicate that these commercially available devices may not meet ANSI/RESNA standards. In addition, the tiller test should be conducted with scooters to further ensure their safety and durability and should use a test dummy with weight capacity according to the mobility device capacity.

Initial development of direct interaction for a transfer robotic Arm system for caregivers.

The most common injuries in healthcare are related to transfers. The Strong Arm system assists caregivers in providing fully dependent transfers from an electric power wheelchair to a bed, shower bench, toilet or other surface. However, this system currently controlled by buttons could be more successful with a more intuitive method during use. This paper presents the initial development of direct interaction for a robotic transfer system called Strong Arm. Direct interaction was used to make a transfer system more intuitive to operate using a three-axis load cell. To move Strong Arm, the user must apply intentional force on any of the given axes by surpassing the axis threshold. Unintentional movement could lead to injury. The results indicate that the thresholds for each axis were at least 3.5 N in X, 16.9 N in Y and 5.3N in Z in order to prevent unintentional forces from a human hand that would cause the robot to move.

Performance evaluation of the Personal Mobility and Manipulation Appliance (PerMMA).

The Personal Mobility and Manipulation Appliance (PerMMA) is a recently developed personal assistance robot created to provide people with severe physical disabilities enhanced assistance in both mobility and manipulation. PerMMA aims to improve functional independence when a personal care attendant is not available on site. PerMMA integrates both a smart powered wheelchair and two dexterous robotic arms to assist its users in completing essential mobility and manipulation tasks during basic and instrumental activities of daily living (ADL). Two user interfaces were developed: a local control interface and a remote operator controller. This paper reports on the evaluation of PerMMA with end users completing basic ADL tasks. Participants with both lower and upper extremity impairments (N=15) were recruited to operate PerMMA and complete up to five ADL tasks in a single session of no more than two hours (to avoid fatigue or frustration of the participants). The performance of PerMMA was evaluated by participants completing ADL tasks with two different control modes: local mode and cooperative control. The users' task completion performance and answers on pre/post-evaluation questionnaires demonstrated not only the ease in learning and usefulness of PerMMA, but also their attitudes toward assistance from advanced technology like PerMMA. As a part of the iterative development process, results of this work will serve as supporting evidence to identify design criteria and other areas for improvement of PerMMA.

Evaluation of lightweight wheelchairs using ANSI/RESNA testing standards.

Lightweight wheelchairs are characterized by their low cost and limited range of adjustment. Our study evaluated three different folding lightweight wheelchair models using the American National Standards Institute/Rehabilitation Engineering Society of North America (ANSI/RESNA) standards to see whether quality had improved since the previous data were reported. On the basis of reports of increasing breakdown rates in the community, we hypothesized that the quality of these wheelchairs had declined. Seven of the nine wheelchairs tested failed to pass the multidrum test durability requirements. An average of 194,502 +/- 172,668 equivalent cycles was completed, which is similar to the previous test results and far below the 400,000 minimum required to pass the ANSI/RESNA requirements. This was also significantly worse than the test results for aluminum ultralight folding wheelchairs. Overall, our results uncovered some disturbing issues with these wheelchairs and suggest that manufacturers should put more effort into this category to improve quality. To improve the durability of lightweight wheelchairs, we suggested that stronger regulations be developed that require wheelchairs to be tested by independent and certified test laboratories. We also proposed a wheelchair rating system based on the National Highway Transportation Safety Administration vehicle crash ratings to assist clinicians and end users when comparing the durability of different wheelchairs.

Factors associated with provision of wheelchairs in older adults.

The objectives of this study were: to identify the factors that are associated with prescription of wheeled mobility devices for older adults, and to determine the effect that living setting has on the types of devices that older adults receive. Retrospective medical chart review at the Center for Assistive Technology on 337 older individuals. These individuals were aged >60 years, and each of them received a new wheeled mobility device from the center during 2007 or 2008. Data were analyzed in three tiers: tier 1 (manual versus powered mobility devices); tier 2 (motorized scooters versus power wheelchairs); and tier 3 (customized versus standard power wheelchairs). For tier 1, the factor associated with higher odds for receipt of manual wheelchairs versus powered were: cognitive limitations (OR = .03). For tier 2, diagnosis of cardio-vascular and pulmonary conditions were associated with prescription of motorized scooters (OR = 3.9). For tier 3, neurological conditions (OR = 3.1), male gender (OR = .37), institutional living (OR = .23), and lower age (OR = .96) were associated with receipt of customized power wheelchairs. This study objectively describes factors associated with prescription of wheeled mobility for older adults. This information can aid in development of guidelines and improving standards of practice for prescription of wheelchairs for older adults.

Analyzing wheelchair mobility patterns of community-dwelling older adults.

This study determined and compared wheelchair mobility patterns for older adults during an organized sporting event and within their community. In July 2008, 39 veterans participating in the 28th National Veterans Wheelchair Games (Omaha, Nebraska) completed the study. Of these, 26 were manual wheelchair and 13 were power wheelchair users. We collected wheelchair-related mobility data using wheelchair data-logging devices. Participants were significantly more active using manual wheelchairs during the games than when using their wheelchairs in their homes in terms of distance traveled (4,466.2 vs 1,367.4 m, p < 0.001) and average speed of propulsion (0.76 vs 0.64 m/s, p < 0.001). The trend was the same for power wheelchair users, with respect to distance (7,306.2 vs 3,450.5 m, p = 0.004) and average speed (0.9 vs 0.7 m/s, p = 0.002). This study demonstrates an objective method of evaluating wheelchair use in community-dwelling older adults.

Manual wheeled mobility--current and future developments from the human engineering research laboratories.

Medical rehabilitation and assistive technology are immersed in a world transitioning to a basis in evidence-based practice. Fortunately, there is a growing body of knowledge related to manual wheelchair mobility to form a basis for clinical decision making. The results from research studies are useful for designing better wheelchairs, fitting and training people appropriately, contributing to evidence-based-medicine and guiding future research. This review describes some of the work related to manual wheelchairs that has and is being conducted within the University of Pittsburgh and the Human Engineering Research Laboratories of the United States Department of Veterans Affairs, and its application.

Manual wheelchair-related mobility characteristics of older adults in nursing homes.

AIM: Manual wheelchairs are commonly prescribed for older adults in nursing homes (NH). The extent of their utilisation being unknown may result in the prescription of standard wheelchairs. The purpose of this study was to quantify manual wheelchair use by nursing home residents. METHODS: Seventy-two independent wheelchair users were recruited from four NH (two VA-affiliated and two private). A customised wheelchair data logger was attached to each participant's wheelchair for 1 month. Data were reduced and compared separately for VA- affiliated and private facilities by types of propulsion pattern (arms versus legs and the combination of arms and legs) using MANOVA. RESULTS: Participants from the VA-affiliated facilities who used their arms were covering more distance (1451 m versus 806 m), with greater endurance (73 m versus 60 m) as compared to participants who used combination of arms and legs. However, no difference was observed between velocity of wheelchair propulsion between groups (0.48 m/s versus 0.58 m/s). For private facilities no notable difference was observed between the groups. CONCLUSION: Older adults who live in NH and use of wheelchairs represent a diverse cohort. The efficacy of using an objective assessment method to measure the extent of use of wheelchairs was demonstrated in this study.

Multiple sclerosis and mobility-related assistive technology: systematic review of literature.

Multiple sclerosis (MS) causes a wide variety of neurological deficits, with ambulatory impairment the most obvious cause of disability. Within 10 to 15 years of disease onset, 80% of persons with MS experience gait problems due to muscle weakness or spasticity, fatigue, and loss of balance. To facilitate mobility, persons with MS frequently use mobility assistive technology (MAT), such as canes, crutches, walkers, wheelchairs, and scooters. We systematically reviewed the published literature on MAT use among persons with MS. We used electronic reference lists such as Ovid MEDLINE and PubMed to search the literature. We located 50 articles that met the initial criteria of providing good evidence of the types of MAT devices and their benefits for individuals with MS. A limited number of articles with higher levels of evidence was found regarding benefits of MAT use specifically for persons with MS. Evidence-based literature provides the basis for the strongest method of measurable clinical performance; therefore, having a strong research study design is vital to the justification of MAT prescription and reimbursement decisions. However, a paucity of studies with higher levels of evidence-based practice exists.