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.

Effect of low-compression balls on wheelchair tennis match-play

The purpose of this study was to compare court-movement variables and physiological responses to wheelchair tennis match-play when using low vs. standard compression tennis balls. Eleven wheelchair basketball players were monitored during repeated bouts of tennis (20 min) using both ball types. Graded and peak exercise tests were completed. For match-play, a data logger was used to record distance and speed. Individual linear heart rate oxygen consumption relationships were used to estimate match-play oxygen uptake. Significant main effects for ball type revealed that total distance (P<0.05), forward distance (P<0.05), and average speed (P<0.05) were higher for play using a low-compression ball. A lower percentage of total time was spent stationary (P<0.001), with significantly more time spent at speeds of 1-1.49 (P<0.05), 1.5-1.99 (P<0.05) and 2.0-2.49 (P<0.05) m ∙ sec(-1) when using the low-compression ball. Main effects for physiological variables were not significant. Greater total and forward distance, and higher average speeds are achieved using a low-compression ball. The absence of any difference in measured HR and estimated physiological responses would indicate that players move further and faster at no additional mean physiological cost. This type of ball will be useful for novice players in the early phases of skill development.

Pressure mapping to assess seated pressure distributions and the potential risk for skin ulceration in a population of sledge hockey players and control subjects

PURPOSE

Ice sledge (or sled) hockey is a fast-paced sport that enables individuals with physical disabilities to play ice hockey. As the attraction to the sport continues to rise, the need for developing better equipment and installing preventative measures for injury will become increasingly important. One such injury includes skin pressure ulceration.

METHOD

A total of 26 subjects including active controls and those with spinal cord injury, multiple sclerosis, limb amputation and traumatic brain injury were studied using a pressure mapping device at the 2012 National Disabled Veterans Winter Sports Clinic to determine the risk for skin pressure ulceration and the impact of cushioning and knee angle positioning on seated pressure distributions.

RESULTS

Sledge hockey athletes may be at increased risk for skin pressure ulceration based on seated pressure distribution data. This experiment failed to demonstrate a benefit for specialty cushioning in either group. Interestingly, knee angle positioning, particularly, knee extension significantly lowered the average seated pressures.

CONCLUSIONS

When considering the risk for skin pressure ulceration, knee angle positioning is of particular clinical importance. More research is warranted, specifically targeting novel cushion and sledge designs and larger groups of individuals with sensory loss and severe spinal deformities. Implications for Rehabilitation Ice sledge (or sled) hockey is a fast-paced and growing adaptive sport played at the Paralympic level. Rehabilitation professionals should consider the potential for skin ulceration in this population of athletes. The effects of cushioning used in the sledge design warrants further investigation. Knee angle positioning; particularly, knee extension significantly lowers seated pressures and may reduce the potential for skin ulceration.

Development of an advanced mobile base for personal mobility and manipulation appliance generation II robotic wheelchair

BACKGROUND

This paper describes the development of a mobile base for the Personal Mobility and Manipulation Appliance Generation II (PerMMA Gen II robotic wheelchair), an obstacle-climbing wheelchair able to move in structured and unstructured environments, and to climb over curbs as high as 8 inches. The mechanical, electrical, and software systems of the mobile base are presented in detail, and similar devices such as the iBOT mobility system, TopChair, and 6X6 Explorer are described.

FINDINGS

The mobile base of PerMMA Gen II has two operating modes: "advanced driving mode" on flat and uneven terrain, and "automatic climbing mode" during stair climbing. The different operating modes are triggered either by local and dynamic conditions or by external commands from users. A step-climbing sequence, up to 0.2 m, is under development and to be evaluated via simulation. The mathematical model of the mobile base is introduced. A feedback and a feed-forward controller have been developed to maintain the posture of the passenger when driving over uneven surfaces or slopes. The effectiveness of the controller has been evaluated by simulation using the open dynamics engine tool.

CONCLUSION

Future work for PerMMA Gen II mobile base is implementation of the simulation and control on a real system and evaluation of the system via further experimental tests.

Assessment of wheelchair driving performance in a virtual reality-based simulator

OBJECTIVE

To develop a virtual reality (VR)-based simulator that can assist clinicians in performing standardized wheelchair driving assessments.

DESIGN

A completely within-subjects repeated measures design.

METHODS

Participants drove their wheelchairs along a virtual driving circuit modeled after the Power Mobility Road Test (PMRT) and in a hallway with decreasing width. The virtual simulator was displayed on computer screen and VR screens and participants interacted with it using a set of instrumented rollers and a wheelchair joystick. Driving performances of participants were estimated and compared using quantitative metrics from the simulator. Qualitative ratings from two experienced clinicians were used to estimate intra- and inter-rater reliability.

RESULTS

Ten regular wheelchair users (seven men, three women; mean age ± SD, 39.5 ± 15.39 years) participated. The virtual PMRT scores from the two clinicians show high inter-rater reliability (78-90%) and high intra-rater reliability (71-90%) for all test conditions. More research is required to explore user preferences and effectiveness of the two control methods (rollers and mathematical model) and the display screens.

CONCLUSIONS

The virtual driving simulator seems to be a promising tool for wheelchair driving assessment that clinicians can use to supplement their real-world evaluations.

Development and evaluation of a gyroscope-based wheel rotation monitor for manual wheelchair users

OBJECTIVE

To develop and evaluate a wireless gyroscope-based wheel rotation monitor (G-WRM) that can estimate speeds and distances traveled by wheelchair users during regular wheelchair propulsion as well as wheelchair sports such as handcycling, and provide users with real-time feedback through a smartphone application.

METHODS

The speeds and the distances estimated by the G-WRM were compared with the criterion measures by calculating absolute difference, mean difference, and percentage errors during a series of laboratory-based tests. Intraclass correlations (ICC) and the Bland-Altman plots were also used to assess the agreements between the G-WRM and the criterion measures. In addition, battery life and wireless data transmission tests under a number of usage conditions were performed.

RESULTS

The percentage errors for the angular velocities, speeds, and distances obtained from three prototype G-WRMs were less than 3% for all the test trials. The high ICC values (ICC (3,1) > 0.94) and the Bland-Altman plots indicate excellent agreement between the estimated speeds and distances by the G-WRMs and the criterion measures. The battery life tests showed that the device could last for 35 hours in wireless mode and 139 hours in secure digital card mode. The wireless data transmission tests indicated less than 0.3% of data loss.

CONCLUSION

The results indicate that the G-WRM is an appropriate tool for tracking a spectrum of wheelchair-related activities from regular wheelchair propulsion to wheelchair sports such as handcycling. The real-time feedback provided by the G-WRM can help wheelchair users self-monitor their everyday activities.

Health risks of vibration exposure to wheelchair users in the community

OBJECTIVE

The purpose of this study was to evaluate whole-body vibration (WBV) exposure to wheelchair (WC) users in their communities and to determine the effect of WC frame type (folding, rigid, and suspension) in reducing WBV transmitted to the person.

DESIGN

An observational case-control study of the WBV exposure levels among WC users.

PARTICIPANTS

Thirty-seven WC users, with no pressure sores, 18 years old or older and able to perform independent transfers.

MAIN OUTCOME MEASURES

WC users were monitored for 2 weeks to collect WBV exposure, as well as activity levels, by using custom vibration and activity data-loggers. Vibration levels were evaluated using ISO 2631-1 methods.

RESULTS

All WC users who participated in this study were continuously exposed to WBV levels at the seat that were within and above the health caution zone specified by ISO 2631-1 during their day-to-day activities (0.83 ± 0.17 m/second(2), weighted root-mean-squared acceleration, for 13.07 ± 3.85 hours duration of exposure). WCs with suspension did not attenuate vibration transmitted to WC users (V = 0.180, F(8, 56) = 0.692, P = 0.697). Conclusions WBV exposure to WC users exceeds international standards. Suspension systems need to be improved to reduce vibrations transmitted to the users.

Functional assessment and performance evaluation for assistive robotic manipulators: Literature review

CONTEXT

The user interface development of assistive robotic manipulators can be traced back to the 1960s. Studies include kinematic designs, cost-efficiency, user experience involvements, and performance evaluation. This paper is to review studies conducted with clinical trials using activities of daily living (ADLs) tasks to evaluate performance categorized using the International Classification of Functioning, Disability, and Health (ICF) frameworks, in order to give the scope of current research and provide suggestions for future studies.

METHODS

We conducted a literature search of assistive robotic manipulators from 1970 to 2012 in PubMed, Google Scholar, and University of Pittsburgh Library System - PITTCat.

RESULTS

Twenty relevant studies were identified.

CONCLUSION

Studies were separated into two broad categories: user task preferences and user-interface performance measurements of commercialized and developing assistive robotic manipulators. The outcome measures and ICF codes associated with the performance evaluations are reported. Suggestions for the future studies include (1) standardized ADL tasks for the quantitative and qualitative evaluation of task efficiency and performance to build comparable measures between research groups, (2) studies relevant to the tasks from user priority lists and ICF codes, and (3) appropriate clinical functional assessment tests with consideration of constraints in assistive robotic manipulator user interfaces. In addition, these outcome measures will help physicians and therapists build standardized tools while prescribing and assessing assistive robotic manipulators.

Criterion validity and accuracy of global positioning satellite and data logging devices for wheelchair tennis court movement

PURPOSE

To compare the criterion validity and accuracy of a 1 Hz non-differential global positioning system (GPS) and data logger device (DL) for the measurement of wheelchair tennis court movement variables.

METHODS

Initial validation of the DL device was performed. GPS and DL were fitted to the wheelchair and used to record distance (m) and speed (m/second) during (a) tennis field (b) linear track, and (c) match-play test scenarios. Fifteen participants were monitored at the Wheelchair British Tennis Open.

RESULTS

Data logging validation showed underestimations for distance in right (DLR) and left (DLL) logging devices at speeds >2.5 m/second. In tennis-field tests, GPS underestimated distance in five drills. DLL was lower than both (a) criterion and (b) DLR in drills moving forward. Reversing drill direction showed that DLR was lower than (a) criterion and (b) DLL. GPS values for distance and average speed for match play were significantly lower than equivalent values obtained by DL (distance: 2816 (844) vs. 3952 (1109) m, P = 0.0001; average speed: 0.7 (0.2) vs. 1.0 (0.2) m/second, P = 0.0001). Higher peak speeds were observed in DL (3.4 (0.4) vs. 3.1 (0.5) m/second, P = 0.004) during tennis match play.

CONCLUSIONS

Sampling frequencies of 1 Hz are too low to accurately measure distance and speed during wheelchair tennis. GPS units with a higher sampling rate should be advocated in further studies. Modifications to existing DL devices may be required to increase measurement precision. Further research into the validity of movement devices during match play will further inform the demands and movement patterns associated with wheelchair tennis.

Autonomous function of wheelchair-mounted robotic manipulators to perform daily activities

Autonomous functions for wheelchair-mounted robotic manipulators (WMRMs) allow a user to focus more on the outcome from the task - for example, eating or drinking, instead of moving robot joints through user interfaces. In this paper, we introduce a novel personal assistive robotic system based on a position-based visual servoing (PBVS) approach. The system was evaluated with a complete drinking task, which included recognizing the location of the drink, picking up the drink from a start location, conveying the drink to the proximity of the user's mouth without spilling, and placing the drink back on the table. For a drink located in front of the wheelchair, the success rate was nearly 100%. Overall, the total time of completing drinking task is within 40 seconds.

The impact of transfer setup on the performance of independent wheelchair transfers

OBJECTIVE

The aim of this study was to determine how selected environmental factors affect transfers and to compare our results to the Americans with Disabilities Act Accessibility Guidelines (ADAAG).

BACKGROUND

Few data are available to support standards development related to transfers in the built environment.

METHOD

Participants were 120 wheeled mobility device (WMD) users who transferred to and from a modular transfer station that consisted of a height-adjustable platform with a lateral grab bar, optional obstacle to the transfer, and an optional height-adjustable front grab bar. Maximum and minimum vertical heights of the transfer surface, maximum gap distance between the WMD and transfer surface, grab bar use, and WMD space needs were recorded.

RESULTS

The 95th percentile lowest and highest heights attained were similar to the median WMD seat-to-floor height (56 cm).We found that 42% (47/113) could not perform a transfer with the obstacle present. Participants transferred higher when the front grab bar was added to the setup (p = .005) and higher and lower with the front grab bar than without it when the obstacle was present in the setup (p = .003 and p = .005, respectively). We found that 95% of participants performed a transfer across an 8.9-cm gap. ADAAG recommendations fall short for the height and clear-space needs of the 50th-percentile WMD users.

CONCLUSION

Revisions concerning transfer heights, gaps, clear spaces, and grab bar heights are necessary to make transfers more accessible to WMD users.

APPLICATION

The data will be used to revise the guidelines related to transfers and to enable designers and engineers to create an environment that is more accessible.

Manuka honey inhibits siderophore production in Pseudomonas aeruginosa

AIMS

The aim of this study was to determine whether manuka honey affected siderophore production by three strains of Pseudomonas aeruginosa.

METHODS AND RESULTS

The minimum inhibitory concentration (MIC) of manuka honey against each of the test bacteria was determined. The effect of manuka honey on siderophore production by three strains of Ps. aeruginosa was investigated using the Chrome azurol S assay (CAS) and CAS-agar plates. Manuka honey at ½ and ¼ of the MIC for each strain led to reduced production of siderophores (1·3-2·2-fold less) which was found to be statistically significant when compared to the untreated control.

CONCLUSIONS

Manuka honey effectively inhibited siderophore production by all three strains of Ps. aeruginosa used in this study. This suggests that manuka honey may impact on bacterial iron homoeostasis and identified a new target for manuka honey in Ps. aeruginosa.

SIGNIFICANCE AND IMPACT OF STUDY

Pseudomonas aeruginosa is an opportunistic human pathogen that can cause acute, life-threatening or persistent wound infections. Part of the virulence repertoire of this micro-organism includes the ability to sequester iron from the host during infection by the synthesis and secretion of siderophores. Manuka honey may limit wound infection by Ps. aeruginosa by limiting its ability to capture iron. This is the first time this mechanism has been investigated.

The Personal Mobility and Manipulation Appliance (PerMMA): a robotic wheelchair with advanced mobility and manipulation

The Personal Mobility and Manipulation Appliance (PerMMA) is a recently developed personal assistance robot developed to provide people with disabilities and older adults enhanced assistance in both mobility and manipulation, which are two fundamental components for independently activities of daily life performing, community participation, and quality of life. Technologies to assist with mobility and manipulation are among the most important tools for clinicians, end users and caregivers; however, there are currently few systems that provide practical and coordinated assistance with mobility and manipulation tasks. The PerMMA was not only developed and evaluated to provide users and caregivers enhanced mobility and manipulation options, but also as a clinical tool as well as research platform. The development and evaluation of PerMMA are presented in the paper.

Virtual electric power wheelchair driving performance of individuals with spastic cerebral palsy

OBJECTIVE

Upper limb spasticity may impair the use of control interfaces such as joysticks for many individuals with disabilities such as cerebral palsy (CP). The aims of this study were to compare the driving performance of those with CP to that of control participants, to identify the impact of lead time on performance, and to compare two joystick designs, a standard movement sensing joystick and a novel isometric joystick.

DESIGN

This study used a repeated-measures design to compare the performance of a group of participants with CP to that of participants without disabilities in a two-dimensional simulated driving task on a computer screen using the two control interfaces. The driving trials used varying "lead times," or the amount of warning time available to make movement decisions and turns. A total of 34 participants with CP and without disability were matched by age and sex into two groups.

RESULTS

Participants with CP had lower driving performance in most variables of interest compared with controls. However, surprisingly, reducing lead time also reduced some performance errors, possibly because of more deliberate driving. The isometric joystick outperformed the movement sensing joystick in terms of performance errors but contributed to a prolonged reaction time.

CONCLUSIONS

The isometric joystick was preferred by participants over the movement sensing joystick in this study and may be a future alternative for individuals with CP for both power mobility and computer access tasks.

Predicting energy expenditure of manual wheelchair users with spinal cord injury using a multisensor-based activity monitor

OBJECTIVE

To develop and evaluate new energy expenditure (EE) prediction models for manual wheelchair users (MWUs) with spinal cord injury (SCI) based on a commercially available multisensor-based activity monitor.

DESIGN

Cross-sectional.

SETTING

Laboratory.

PARTICIPANTS

Volunteer sample of MWUs with SCI (N=45).

INTERVENTION

Subjects were asked to perform 4 activities including resting, wheelchair propulsion, arm-ergometer exercise, and deskwork. Criterion EE using a metabolic cart and raw sensor data from a multisensor activity monitor was collected during each of these activities.

MAIN OUTCOME MEASURES

Two new EE prediction models including a general model and an activity-specific model were developed using enhanced all-possible regressions on 36 MWUs and tested on the remaining 9 MWUs.

RESULTS

The activity-specific and general EE prediction models estimated the EE significantly better than the manufacturer's model. The average EE estimation error using the manufacturer's model and the new general and activity-specific models for all activities combined was -55.31% (overestimation), 2.30% (underestimation), and 4.85%, respectively. The average EE estimation error using the manufacturer's model, the new general model, and activity-specific models for various activities varied from -19.10% to -89.85%, -18.13% to 25.13%, and -4.31% to 9.93%, respectively.

CONCLUSIONS

The predictors for the new models were based on accelerometer and demographic variables, indicating that movement and subject parameters were necessary in estimating the EE. The results indicate that the multisensor activity monitor with new prediction models can be used to estimate EE in MWUs with SCI during wheelchair-related activities mentioned in this study.