Mini-review: Robotic wheelchair taxonomy and readiness

Robotic wheelchair research and development is a growing sector. This article introduces a robotic wheelchair taxonomy, and a readiness model supported by a mini-review. The taxonomy is constructed by power wheelchair and, mobile robot standards, the ICF and, PHAATE models. The mini-review of 2797 articles spanning 7 databases produced 205 articles and 4 review articles that matched inclusion/exclusion criteria. The review and analysis illuminate how innovations in robotic wheelchair research progressed and have been slow to translate into the marketplace.

Towards the Development of a Learning-Based Intention Classification Framework for Pushrim-Activated Power-Assisted Wheelchairs

There has been a growth in the design and use of power assist devices for manual wheelchairs (MWCs) to alleviate the physical load of MWC use. A pushrim-activated power-assisted wheel (PAPAW) is an example of a power assist device that replaces the conventional wheel of a MWC. Although the use of PAPAWs provides some benefits to MWC users, it can also cause difficulties in maneuvering the wheelchair. In this research, we examined the characteristics of wheelchair propulsion when using manual and powered wheels. We used the left and right wheels' angular velocity to calculate the linear and angular velocity of the wheelchair. Results of this analysis revealed that the powered wheel's controller is not optimally designed to reflect the intentions of a wheelchair user. To address some of the challenges with coordinating the pushes on PAPAWs, we proposed the design of a user-intention detection framework. We used the kinematic data of MWC experiments and tested six supervised learning algorithms to classify one of four movements: "not moving", "moving straight forward", "turning left", and "turning right". We found that all the classification algorithms determined the type of movement with high accuracy and low computation time. The proposed intention detection framework can be used in the design of learning-based controllers for PAPAWs that take into account the individualized characteristics of wheelchair users. Such a system may improve the experience of PAPAW users.

Rare diseases: matching wheelchair users with rare metabolic, neuromuscular or neurological disorders to electric powered indoor/outdoor wheelchairs (EPIOCs)

PURPOSE

To describe the clinical features of electric powered indoor/outdoor wheelchair (EPIOC) users with rare diseases (RD) impacting on EPIOC provision and seating.

METHOD

Retrospective review by a consultant in rehabilitation medicine of electronic and case note records of EPIOC recipients with RDs attending a specialist wheelchair service between June 2007 and September 2008. Data were systematically extracted, entered into a database and analysed under three themes; demographic, diagnostic/clinical (including comorbidity and associated clinical features (ACFs) of the illness/disability) and wheelchair factors.

RESULTS

Fifty-four (27 male) EPIOC users, mean age 37.3 (SD 18.6, range 11-70) with RDs were identified and reviewed a mean of 64 (range 0-131) months after receiving their wheelchair. Diagnoses included 27 types of RDs including Friedreich's ataxia, motor neurone disease, osteogenesis imperfecta, arthrogryposis, cerebellar syndromes and others. Nineteen users had between them 36 comorbidities and 30 users had 44 ACFs likely to influence the prescription. Tilt-in-space was provided to 34 (63%) users and specialised seating to 17 (31%). Four users had between them complex control or interfacing issues.

CONCLUSIONS

The complex and diverse clinical problems of those with RDs present unique challenges to the multiprofessional wheelchair team to maintain successful independent mobility and community living. Implications for Rehabilitation Powered mobility is a major therapeutic tool for those with rare diseases enhancing independence, participation, reducing pain and other clinical features. The challenge for rehabilitation professionals is reconciling the physical disabilities with the individual's need for function and participation whilst allowing for disease progression and/or growth. Powered wheelchair users with rare diseases with a (kypho) scoliosis require a wheelchair system that balances spine stability and movement to maximise residual upper limb and trunk function. The role of specialised seating needs careful consideration in supporting joint derangements and preventing complications such as pressure sores.

Physical medicine devices; reclassification of stair-climbing wheelchairs. Final order

The Food and Drug Administration (FDA) is issuing a final order to reclassify stair-climbing wheelchairs, a class III device, into class II (special controls) based on new information and subject to premarket notification, and further clarify the identification.

Promote pressure ulcer healing in individuals with spinal cord injury using an individualized cyclic pressure-relief protocol

OBJECTIVE

To evaluate whether an individualized cyclic pressure-relief protocol accelerates wound healing in wheelchair users with established pressure ulcers (PrUs).

DESIGN

Randomized controlled study.

SETTING

Spinal cord injury clinics.

PARTICIPANTS

Forty-four subjects, aged 18-79 years, with a Stage II or Stage III PrU, were randomly assigned to the control (n = 22) or treatment (n = 22) groups.

INTERVENTIONS

Subjects in the treatment group used wheelchairs equipped with an individually adjusted automated seat that provided cyclic pressure relief, and those in the control group used a standard wheelchair. All subjects sat in wheelchairs for a minimum of 4 hours per day for 30 days during their PrU treatment.

MAIN OUTCOME MEASURES

Wound characteristics were assessed using the Pressure Ulcer Scale for Healing (PUSH) tool and wound dimensions recorded with digital photographs twice a week. Median healing time for a 30% healing relative to initial measurements, the percentage reduction in wound area, and the percentage improvement in PUSH score achieved at the end of the trial were compared between groups.

RESULTS

At the end of 30 days, both groups demonstrated a general trend of healing. However, the treatment group was found to take significantly less time to achieve 30% healing for the wound measurement compared with the control group. The percentage improvement of the wound area and PUSH scores were greater in using cyclic seating (45.0 +/- 21.0, P < .003; 29.9 +/- 24. 6, P < .003) compared with standard seating (10.2 +/- 34.9, 5.8 +/- 9.2).

CONCLUSIONS

The authors' findings show that cyclically relieving pressure in the area of a wound for seated individuals can greatly aid wound healing. The current study provides evidence that the individualized cyclic pressure-relief protocol helps promote pressure wound healing in a clinical setting. The authors concluded that the individualized cyclic pressure relief may have substantial benefits in accelerating the healing process in wheelchair users with existing PrUs, while maintaining the mobility of individuals with SCI during the PrU treatment.

Comparison between performance with a pushrim-activated power-assisted wheelchair and a manual wheelchair on the Wheelchair Skills Test

PURPOSE

To test the hypothesis that people using a pushrim-activated power-assisted wheelchair (PAPAW) can accomplish a wider range of wheelchair skills than when using a manual wheelchair (MWC).

METHODS

We studied 30 able-bodied participants, using within-participant comparisons. Participants used a manual wheelchair equipped with both PAPAW and regular MWC rear wheels, and rear anti-tip devices (Arc-RADs) that permitted wheelie-like function. We trained participants to perform the wheelchair skills of the Wheelchair Skills Training Program (WSTP, Version 2.4). From the Wheelchair Skills Test (WST, Version 2.4), we calculated pass-fail success rates for the 50 individual skills and a total percentage WST score.

RESULTS

The mean (+/-SD) total WST scores were 89.3 (+/-7.0)% for the PAPAW and 88.8 (+/-8.4)% for the MWC, with a mean difference of 0.6 (+/-5.6)% (p = 0.59). Qualitative observations suggested that skills requiring a higher force on the pushrim (e.g., incline ascent) were performed more easily with the PAPAW, whereas skills requiring greater control of the wheelchair (e.g., wheelie-dependent skills) were performed more easily with the MWC.

CONCLUSION

Overall wheelchair skill performance with the PAPAW is not superior to that when using the MWC. The PAPAW may be helpful for specific skills that require more wheel torque, but the additional torque appears to be disadvantageous when performing skills that require greater control.

Smart wheelchairs: A literature review

Several studies have shown that both children and adults benefit substantially from access to a means of independent mobility. While the needs of many individuals with disabilities can be satisfied with traditional manual or powered wheelchairs, a segment of the disabled community finds it difficult or impossible to use wheelchairs independently. To accommodate this population, researchers have used technologies originally developed for mobile robots to create "smart wheelchairs." Smart wheelchairs have been the subject of research since the early 1980s and have been developed on four continents. This article presents a summary of the current state of the art and directions for future research.

Test-Retest Reliability, Internal Item Consistency, and Concurrent Validity of the Wheelchair Seating Discomfort Assessment Tool

Discomfort is a common problem for wheelchair users. Few researchers have investigated discomfort among wheelchair users or potential solutions for this problem. One of the impediments to quantitative research on wheelchair seating discomfort has been the lack of a reliable method for quantifying seat discomfort. The purpose of this study was to establish the test-retest reliability, internal item consistency, and concurrent validity of a newly developed Wheelchair Seating Discomfort Assessment Tool (WcS-DAT). Thirty full-time, active wheelchair users with intact sensation were asked to use this and other tools in order to rate their levels of discomfort in a test-retest reliability study format. Data from these measures were analyzed in SPSS using an intraclass correlation coefficient (ICC) model (2,k) to measure the test-retest reliability. Cronbach's alpha was used to examine the internal consistency of the items within the WcS-DAT. Concurrent validity with similar measures was analyzed using Pearson product-moment correlations. ICC scores for all analyses were above the established lower bound of .80, indicating a highly stable and reliable tool. In addition, alpha scores indicated good consistency of all items without redundancy. Finally, correlations with similar tools, such as the Chair Evaluation Checklist and the Short Form of the McGill Pain Questionnaire, were significant at the .05 level, and many were significant at the .001 level. These results support the use of the WcS-DAT as a reliable and stable tool for quantifying wheelchair seating discomfort. Its application will enhance the ability to assess and to research this important problem and will provide a means to validate the outcomes of specialized seating interventions for the study population of wheelchairs users.

The Role of Wheelchair Seating Standards in Determining Clinical Practices and Funding Policy

The development of international standards for wheelchair seating offers practical benefits in the process of matching technical characteristics of assistive technologies to individual user needs. However, information provided in technical test reports must be treated with caution when aggregating technical characteristics to classify products or when implementing funding policy. This article suggests that clustering technical characteristics of seat cushions in isolation of clinical and other user requirements is not a viable way to establish product funding codes that are responsive to clinical need.

New wheelchair keeps people on the move

The iBOT 3000 Mobility System allows users to move around at an elevated height. The system uses the I-Balance Technology to actively maintain stability by driving the wheels to stay under the user.

Powered wheelchairs and independence in young children with tetraplegia

The aim of this study was to assess the effect of early provision (< or = 8 years) of a powered wheelchair (PWC) in children with tetraplegia. Twenty-nine children (15 males, 14 females; mean age 6 years 3 months, age range 3 to 8 years) with spastic or dystonic tetraplegia were studied. All participants had severe motor impairment. Treatment outcomes were investigated in several dimensions of disablement: Impairment, Functional Limitation/Activity, Disability/Participation. It was found that the level of independence improved significantly after PWC provision, while motor impairment, IQ, and quality of life did not. The majority of children (21 of 27) reached a level of driving competence which allowed them to move around with or without minimal (i.e. verbal) adult support. Achievement of this competence was not statistically related to IQ or motor impairment but correlated to the time spent in the PWC. The majority of parents (21 of 25) were not in favour of the PWC when the study started but after PWC provision, 23 of 25 parents expressed positive feelings about it. Reactions of the majority of children (23 of 25) were positive from the beginning of the study and did not change over time. The authors concluded that PWCs can aid independence and socialization and the majority of children can achieve a good-enough driving competence, even those with severe learning disability or motor deficit. PWCs should not be viewed as a last resort but as a means of providing efficient self-locomotion in children with a severe motor deficit.

Energy cost of propulsion in standard and ultralight wheelchairs in people with spinal cord injuries

BACKGROUND AND PURPOSE

Wheelchair- and subject-related factors influence the efficiency of wheelchair propulsion. The purpose of this study was to compare wheelchair propulsion in ultralight and standard wheelchairs in people with different levels of spinal cord injury.

SUBJECTS

Seventy-four subjects (mean age=26.2 years, SD=7.14, range=17-50) with spinal cord injury resulting in motor loss (30 with tetraplegia and 44 with paraplegia) were studied.

METHOD

Each subject propelled standard and ultralight wheelchairs around an outdoor track at self-selected speeds, while data were collected at 4 predetermined intervals. Speed, distance traveled, and oxygen cost (VO2 mL/kg/m) were compared by wheelchair, group, and over time, using a Bonferroni correction.

RESULTS

In the ultralight wheelchair, speed and distance traveled were greater for both subjects with paraplegia and subjects with tetraplegia, whereas VO2 was less only for subjects with paraplegia. Subjects with paraplegia propelled faster and farther than did subjects with tetraplegia.

CONCLUSION AND DISCUSSION

The ultralight wheelchair improved the efficiency of propulsion in the tested subjects. Subjects with tetraplegia, especially at the C6 level, are limited in their ability to propel a wheelchair.

Braking electric-powered wheelchairs: effect of braking method, seatbelt, and legrests

OBJECTIVE

To examine the influence of three electric-powered wheelchair braking conditions and four wheelchair seating conditions on electric-powered wheelchair motion and Hybrid II test dummy motion. This study provides quantitative information related to assessing the safety of electric-powered wheelchair driving.

DESIGN

Rehabilitation engineering comparison and ANSI/ RESNA standards testing. Convenience sample of eight different electric-powered wheelchairs. Within-chair comparisons were conducted.

INTERVENTION

Electric-powered wheelchairs were compared under three braking scenarios (joystick release, joystick reverse, power-off) and four seating conditions (seatbelt and legrests, seatbelt and no legrests, no seatbelt but legrests, no seatbelt and no legrests).

SETTING

A rehabilitation engineering center.

MAIN OUTCOME MEASURES

The braking distance, braking time, and braking accelerations for electric-powered wheelchairs during three braking scenarios; trunk motion, head motion, and trunk angular acceleration during three braking scenarios and four seating conditions; and number of falls from the wheelchairs for three braking scenarios and four seating conditions.

RESULTS

Significant differences (p < .05) were found in braking distance, braking time, and braking acceleration when comparing the joystick release and joystick reverse scenarios with the power-off scenario. The mean braking distance was shortest with the power-off braking scenario (.89m), whereas it was longest when the joystick was released (1.66m). Significant differences (p < .05) in head displacement and trunk angular displacement were observed among braking conditions and between seating conditions. There were also significant differences (p = .0011) among braking conditions for maximum trunk angular acceleration. The Hybrid II test dummy fell from the wheelchairs with highest frequency when there were no legrests and no seatbelt used.

CONCLUSION

The results of this study indicate that use of a seatbelt when driving an electric-powered wheelchair reduces the risk of falling from a wheelchair. Furthermore, the use of legrests can reduce the risk of injury to the wheelchair driver. This study shows that the most abrupt braking occurs when deactivating the power switch.

Wheelchair rider injuries: causes and consequences for wheelchair design and selection

An understanding of adverse incidents and injuries sustained by active wheelchair riders, who live and work in the mainstream of society, is needed to improve safety via wheelchair design, selection, and configuration. We interviewed 109 riders who had experienced incidents, in order to identify the causes of incidents and injuries they suffered. Participants reported n = 253 incidents (53% in powered wheelchairs, 47% manual) occurring within a 5-year period, comprised of 106 (42%) "Tips and Falls," 84 (33%) "Component Failures," and 63 (25%) "Other" events. Sixty-eight (27%) of the incidents caused injuries requiring medical attention, including 13 hospitalizations. Direction of Tips and Falls was associated with wheelchair type (manual or powered) and with different riding surfaces. Aspects of wheelchair stability, particularly the effects of wheelchair configuration and of different riding surfaces, are important engineering issues affecting wheelchair safety. Interpretation of the results highlights wheelchair stability mechanics. Potential design improvements are discussed.

The voice of the customer: consumers define the ideal battery charger

The Rehabilitation Engineering Research Center on Technology Evaluation and Transfer is exploring how the users of assistive technology devices define the ideal device. This work is called the Consumer Ideal Product program. The results show what device characteristics are most and least important, indicating where to place the priority on product features and functions from the consumer's perspective. The "voice of the customer" can be used (1) to define the ideal characteristics of a product, (2) to make trade-offs in product design and function improvements based on their relative importance to the consumer, (3) to compare the characteristics of existing products against the characteristics of the ideal product, or (4) to generate a product checklist for consumers to use when making a purchase decision. This paper presents the results of consumers' defining the ideal battery charger. Four focus groups generated the survey's content, then 100 experienced users rated 159 characteristics organized under 11 general evaluation criteria. The consumers placed the highest importance on characteristics from the general evaluation criteria of product reliability, effectiveness, and physical security/safety. The findings should help manufacturers and vendors improve their products and services and help professionals and consumers make informed choices.

Wheeled mobility device database for transportation safety research and standards

To address the issue of safely accessing and securing wheeled mobility devices in motor vehicles, more information characterizing current-production devices was needed. In a recent effort, frame characteristics of wheeled mobility devices were defined and a database developed for recording characteristics relevant to access and securement. A representative number of devices have been surveyed to measure key characteristics, and these measures have been recorded in the database. This paper details the development of the database and frame characterization scheme, the methods used to survey currently available wheeled mobility devices, and some descriptive statistics resulting from an analysis of the data. A discussion of how this information is being used in research aimed at developing technology and safety standards to ensure vehicle access and safe transportation, as well as other potential uses, is also included.

Determination of gross weight limit for foldaway powered wheelchairs through isometric and psychophysical strength simulations

This study concerns the maximum weight of a powered wheelchair for transfer to and from the trunk of a car by individuals with limited exercise endurance. The loading and unloading of a folded wheelchair from the trunk of a medium size American car was simulated. Both static and dynamic simulations were carried out. The isometric (static) and psychophysical (dynamic) strengths of eight adult males while simulating the loading/unloading activities were measured. The results indicated that: (1) the maximum weight of a powered foldaway wheelchair that individuals can load in the car and unload from the car is much lower than the weight of most commercially available powered wheelchairs, and (2) static simulation of the folded wheelchair loading and unloading activity provides wheelchair weight ceiling that is easily exceeded during the dynamic simulation of the activity. The upper limit on the weight of a foldaway powered wheelchair is provided and implications of this limit on future foldaway powered wheelchair designs are briefly discussed. In addition, the user gender and age effects on the foldaway powered wheelchair weight ceiling are also discussed.