Participatory Action Design and Engineering of Powered Personal Transfer System for Wheelchair Users: Initial Design and Assessment.

Caregivers that assist with wheelchair transfers are susceptible to back pain and occupational injuries. The study describes a prototype of the powered personal transfer system (PPTS) consisting of a novel powered hospital bed and a customized Medicare Group 2 electric powered wheelchair (EPW) working together to provide a no-lift solution for transfers. The study follows a participatory action design and engineering (PADE) process and describes the design, kinematics, and control system of the PPTS and end-users' perception to provide qualitative guidance and feedback about the PPTS. Thirty-six participants (wheelchair users (n = 18) and caregivers (n = 18)) included in the focus groups reported an overall positive impression of the system. Caregivers reported that the PPTS would reduce the risk of injuries and make transfers easier. Feedback revealed limitations and unmet needs of mobility device users, including a lack of power seat functions in the Group-2 wheelchair, a need for no-caregiver assistance/capability for independent transfers, and a need for a more ergonomic touchscreen. These limitations may be mitigated with design modifications in future prototypes. The PPTS is a promising robotic transfer system that may aid in the higher independence of powered wheelchair users and provide a safer solution for transfers.

Differences between manufacturers in reported power wheelchair repairs and adverse consequences among people with spinal cord injury.

OBJECTIVE: To compare the frequency of power wheelchair (PWC) repairs and consequences experienced over a 6-month period by individuals with spinal cord injury (SCI) who use a PWC ≥40h/wk, based on manufacturer, seating functions, Healthcare Common Procedure Coding System (HCPCS) group, and model, and over time. DESIGN: Convenience observational sample survey. SETTING: Spinal Cord Injury Model System centers. PARTICIPANTS: Individuals with SCI (N=945) who use a PWC ≥40h/wk. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Number of required wheelchair repairs and resulting consequences (ie, being stranded, missing work/school, or missing a medical appointment). RESULTS: Rates of required repairs (47.6%-63.3%) and consequences (26.7%-40.7%) were high across manufacturers. Differences between manufacturers were found among PWCs without seating functions (P<.001-.008) and among group 2 wheelchairs (P=.007). Across the 10 most prescribed wheelchairs in this study, 54.5% to 73.9% of users required 1 or more repairs over a 6-month period. Increases in the number of repairs were also found for several PWC manufacturers with time. Differences were found in participant age, working status, years since injury, and presence of seating functions between manufacturers. CONCLUSIONS: The differences found in the number of repairs reported by survey respondents based on PWC manufacturer and the increases in repairs over time require further evaluation.

Evaluation of Electric and Air-Powered Shopping Scooters in Grocery Stores.

OBJECTIVE: The purpose of this study was to further previous research and gather additional information regarding the usage of motorized shopping scooters as well as feedback for improvements to an air-powered scooter. METHODS: Online surveys were used to assess individuals' shopping characteristics and experience using the motorized scooters and to gather feedback from store employees regarding their experience. K-Means clustering analysis was used to determine user demographics who chose to use the air-powered scooter versus the electric powered scooter while shopping. RESULTS: A total of 127 individuals provided informed consent, 65 individuals from Site 1 and 62 individuals from Site 2. 120 participants met the inclusion criteria and completed the survey. K-Means clustering found that age, type of personal mobility device, shopping bill total, and frequency using a motorized shopping scooter to be significant factors in whether individuals chose to use an air-powered scooter or electric-powered scooter. CONCLUSION: Motorized shopping scooters are in high demand and used by a wide variety of individuals, yet electric-powered scooters are commonly unavailable due to having dead batteries or all the devices being in use. Air-powered scooters may serve as a practical replacement for the current electric-powered scooters found in grocery and retail stores.

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.

Anthropomorphic model rigid loading indenter with embedded sensor development for wheelchair cushion standard testing.

Develop an anthropomorphic model cushion rigid loading indenter with embedded sensors (AMCRLI-ES) to assess compression and shear forces at key locations such as trochanters and ischial tuberosities. The sensor design was optimized using finite element analysis. The AMCRLI-ES was designed with the same dimensions as specified in ISO 16840-2 tests. The AMCRLI-ES is divided into eight independent sections, and each section consists of one 3-axis load cell sensor to measure compression and shear forces normal to the compression direction. Six commercial cushions were tested using the AMCRLI-ES with standard ISO 16840-2 testing procedures. Statistical differences were found for energy dissipation between cushions. Statistical differences (p < 0.001) were found in all stiffness values. Test results showed that energy dissipation (ED) was correlated with hysteresis at 500 N with moderate to high Pearson product correlation r = -0.537, p = 0.022. The hysteresis at 250 N did not show a statistical correlation with ED. The AMCRLI-ES demonstrated the ability to measure compression and shear forces at key locations on the cushion including the thigh, trochanter, ischial tuberosity, and sacral area. It provides in-depth information about how the weight was distributed on the cushions.

Participatory action design and engineering of a manual wheelchair virtual coach including in-home and community usage.

BACKGROUND: Current clinical practice guidelines (CPG) recommend periodic pressure redistribution (PR) to alter sitting pressure and reduce the risk of developing pressure injuries (PI). Individuals who have strength and trunk stability are asked to perform PR such as wheelies, leaning laterally, and forward-leaning to minimize the duration of pressure acting on the same region of the body. OBJECTIVE: Our long-term objective is to build upon previous research and development to create a more effective device for improving PR training and adherence to CPG among manual wheelchair users (MWU). Through this study, we employed a participatory action design and engineering (PADE) approach in developing the hardware and user interface to increase the likelihood of eventually yielding a device effective for both MWU and clinicians. PARTICIPANTS: Focus Groups: Ten clinicians - 6 physical therapists, 3 occupational therapists, and one registered nurse, and 10 MWU with spinal cord injuries (SCI) who reported using their wheelchairs 40-80 h per week. Five-Day Assessment: Five male MWU with SCI who had been wheelchair users for 18.5 ± 16.2 years. Four-Week Investigation: The 7 participants with SCI were 5 males and 2 females, who had been wheelchair users for 24.7 ± 17.0 years. METHODS: A PADE approach was used to improve upon a manual wheelchair virtual coaching system for people with SCI. The system comprises a seat support instrumented with force sensors, software algorithms to detect PR, and a smart phone app for user interface. The methods included three stages: multiple focus groups, a five-day evaluation phase with participants using their own wheelchairs in their homes and communities, and a 4-week assessment with improvements made based on the 5-day results by users with their own wheelchairs in their homes and communities. RESULTS: The focus groups yielded guidance for ergonomics, user interface, charging frequency, and key dimensions and mass. The 5-day study identified mechanical, electrical, and connectivity challenges, which were resolved before the 4-week study. The 4-week trial suggested that participants performed PR less frequently than clinically recommended and provided an indication of the types of maneuvers that they performed. CONCLUSION: A prototype manual wheelchair virtual coaching system was developed using a PADE process. The system was able to detect and record PR in home and community environments. Following improvements identified in this study, a future version will be tested with additional users to determine whether it can improve adherence to PR guidance.

Comparing the performance of ultralight folding manual wheelchairs using standardized tests.

OBJECTIVE: To evaluate ultralight folding manual wheelchairs (UFMWs) in order to produce comparative data on their strength, durability, stability and cost-benefit, and to determine progress of wheelchairs by comparing these results to results of past studies. DESIGN: Engineering testing using American National Standards Institute (ANSI) and Rehabilitation Engineering and Assistive Technology Society of North America (RESNA) standards. SETTING: Laboratory testing of UFMW stability, and static, impact and fatigue strength performance with three devices using ANSI/RESNA standardized tests. PARTICIPANTS: The three wheelchair models were the TiLite Aero X (Permobil, Lebanon, TN), Sunrise Medical Quickie 2 (Fresno, CA) and Ki Mobility Catalyst 5 (Stevens Point, WI). INTERVENTIONS: ANSI/RESNA standardized tests. MAIN OUTCOME MEASURES: Mass and critical measurements, static stability, static strength, impact strength, fatigue strength and cost analysis. RESULTS: The ultralight folding wheelchairs continued to outperform their lightweight and rigid framed counterparts. According to these data, the quality of ultralight wheelchairs has not declined over the past 10 years. The Ki Catalyst did not pass strength and durability testing, while the TiLite Aero X and Sunrise Medical Quickie 2 surpassed these tests. CONCLUSIONS: This result exemplifies the need for ongoing research to identify whether wheelchairs satisfy ANSI/RESNA testing requirements and highlights the importance of creating a resource data set. This is particularly important when numerous other wheelchairs fail to meet minimum ANSI/RESNA requirements.Implications for RehabilitationFolding frame wheelchairs offer benefits such as transportability and convenience that may benefit certain wheelchair users, assuming their durability is sufficient and they provide similar benefits vs. other wheelchair construction.Previous studies have shown that folding wheelchairs perform meet the minimum requirements of standardized testing, and it is important to see if durability has increased, decreased or remained the same over the years. Other wheelchair types have remained stagnant with respect to durability and are less likely to meet the minimum durability requirements.Durable devices will improve a wheelchair user's quality of life by reducing downtime while waiting for repairs, and also reduce the likelihood of injury due to component failure.

Air-powered shopping carts in grocery stores: a pilot study.

PURPOSE: Motorized shopping carts found at grocery and retail stores provide mobility for those who have difficulty walking through the store or pushing a regular cart. The purpose of this study was to understand the usage of motorized carts in grocery stores and pilot test an air-powered cart to determine its feasibility as a replacement for electric-powered carts as well as identify areas for improvement and preferred users. METHODS: Users were asked to complete an online survey that assessed their shopping characteristics and experience using the motorized cart. K-Means clustering determined user demographics who chose to use the air-powered carts versus the electric-powered carts. Open-ended comments for improvements were also collected. RESULTS: A total of 65 participants were provided informed consent, 60 participants met inclusion criteria and completed the survey. A majority of the air-powered (N = 29, 91%) and electric-powered (N = 11, 73%) cart users had a positive experience. Clustering found age and type of mobility device owned were significant whether participants chose the air-powered or electric-powered carts. Most suggested improvements for the air-powered carts were better braking, higher speed and a bigger basket while a longer battery life was most suggested for electric-powered carts. CONCLUSIONS: Motorized shopping carts are used by a wide variety of individuals. Individuals aged 54 or younger and do not own a mobility device chose to use air-powered more than electric-powered carts. The functional capabilities of the air-powered carts demonstrated their potential to serve as practical replacements for electric-powered carts found in grocery and retail stores.Implications for rehabilitationThe availability and reliability of motorized shopping carts at retail stores are integral for individuals with physical impairments to complete their shopping needs.The development of novel assistive devices such as air-powered carts provides improved experiences and quality of life.Integrating end-user feedback during the design of assistive technologies is paramount for meeting actual needs.

Design of an adjustable wheelchair for table tennis participation.

PURPOSE: Physical activity and recreation are very important for people with disabilities and provide benefits for self-esteem, social relationships, employment, rehabilitation, and education. Para Table Tennis is an adaptive sport where participants compete in table tennis while sitting in a wheelchair. However, athletes generally use their everyday wheelchair instead of a device specifically designed for the sport. The specific support, movements, and posture needed to participate in table tennis at the highest level are different than general day-to-day mobility and a device could be optimized for the sport. This research describes the development of a wheelchair specifically designed for para table tennis. MATERIALS AND METHODS: The design followed a participatory action design approach which identified the specific needs for a wheelchair to be used during para table tennis. RESULTS: Three design needs were identified which included 1) locking the casters in the forward direction, 2) ability to raise the seat height as high as possible while allowing the user's knees to fit under the table, and 3) adjustable seat angle which will allow some users to have anterior tilt to get their trunk even higher while other users could have posterior tilt for stability. A new chair meeting these needs was designed and prototyped. CONCLUSIONS: Para table tennis has some specific requirements related to movements and posture which were improved by a new wheelchair design specific for the sport.IMPLICATIONS FOR REHABILITATIONMany adaptive sports are improved with sport specific technology.A model client was used to develop a wheelchair specifically for adaptive table tennis.The height and angle of the seat of the new wheelchair can be adjusted for optimal stability and reach.The casters of the new wheelchair can be locked to allow only forward and backward motion.

Comparison of carbon fibre and aluminium materials in the construction of ultralight wheelchairs.

Carbon fibre-reinforced polymers have been used in the sporting goods industry for decades, and wheelchairs have incorporated the material since the late 1980s. There is no independently collected data available on carbon fibre-reinforced polymer wheelchairs' performance on the ANSI/RESNA testing standards, however. This study evaluated three full carbon fibre wheelchair specimens to determine their performance versus similar wheelchairs. Testing determined that while the frames survived more testing cycles than any other wheelchair, the casters and rear tires failed similarly to other devices. Overall, due to the purchase cost, the cost benefit of the tested wheelchair model was similar to aluminium wheelchairs.Implications for rehabilitationCarbon fibre wheelchair construction is a viable alternative to aluminium, titanium, or steel construction, and decreasing costs will continue to improve the benefits of carbon fibre over these modelsCarbon fibre wheelchair found to be more durable than aluminium models, but are also much more expensive. The additional cost may be justified for some users that need the increased durability, howeverIncreased durability will reduce the number of repairs and warranty claims, potentially reducing the burden on a wheelchair user, and also improving their ability to travel and participate in their communityThe low weight of carbon fibre wheelchairs may increase the mobility of some users by allowing them to transfer more easily into and out of vehicles and manoeuvre throughout the environment.

Design and operation verification of an automated pressure mapping and modulating seat cushion for pressure ulcer prevention.

A sensorized air cell-based seat cushion system was developed to address the issues of loading magnitude and duration at a sitting interface to aid in reducing risk of sitting acquired pressure ulcers. This system is capable of pressure mapping, redistribution, and offloading which were verified using an anthropomorphic model and a human subject. The system is comprised of an air cell array cushion, a pneumatic control unit, and a graphical user interface. ISO load deflection testing confirmed that the cushion's loading response is comparable to commercial air cell-based seat cushions. Testing demonstrated that the internal pressure of the air cells are indicative of interface pressure and can be used as input to pressure modulating algorithms. Uniform pressure distribution was achieved through automated pressure redistribution algorithm implementation where the immersion of a subject into the seat cushion increased and interface pressure decreased. High pressure point identification and automatic offloading were performed in which newly created high pressure points were addressed using subsequent redistribution. Pressure mapping enabled offloading and redistribution can objectively manage the effects of loading magnitude and duration at the sitting interface.

Comparison of High-Strength Aluminum Ultralight Wheelchairs Using ANSI/RESNA Testing Standards.

Background: The use of ultralight manual wheelchairs has been shown to benefit wheelchair users when compared to other types. New aluminum alloy frame materials coming to the market have not been independently evaluated for durability and cost benefit. Methods: Three 70XX aluminum ultralight wheelchair models were tested and compared based on dimensions, stability, and durability using the ANSI/RESNA standards. The results were also compared to previous manual wheelchair studies. Results: This study found that there were no significant cost benefit or durability differences between the wheelchairs tested and previous aluminum or titanium ultralight rigid models. Additionally, 5 of the 9 wheelchairs tested failed to meet the minimum ANSI/RESNA requirements for durability. Conclusion: These results are similar to results from previous rigid ultralight wheelchair studies and indicate that the quality of wheelchairs of this type has not improved and better requirements are necessary for wheelchairs marketed in the United States.

Kinematics and Stability Analysis of a Novel Power Wheelchair When Traversing Architectural Barriers.

Background: Electric-powered wheelchairs (EPWs) are essential devices for people with disabilities for mobility and quality of life. However, the design of common EPWs makes it challenging for users to overcome architectural barriers, such as curbs and steep ramps. Current EPWs lack stability, which may lead to tipping the EPW causing injury to the user. An alternative Mobility Enhancement Robotic Wheelchair (MEBot), designed at the Human Engineering Research Laboratories (HERL), was designed to improve the mobility of, and accessibility for, EPW users in a wide variety of indoor and outdoor environments. Seat height and seat inclination can be adjusted using pneumatic actuators connected to MEBot's 6 wheels. Method: This article discusses the design and development of MEBot, including its kinematics, stability margin, and calculation of the center of mass location when performing its mobility applications of curb climbing/descending and attitude control. Motion capture cameras recorded the seat angle and joint motion of the 6 wheel arms during the curb climbing/descending process. The center of mass location was recorded over a force plate for different footprint configurations. Results: Results showed that the area of the footprint changed with the location of the wheels during the curb climbing/descending and attitude control applications. The location of the center of mass moved ±30 mm when the user leaned sideways, and the seat roll and pitch angle were 0° and ±4.0°, respectively, during curb climbing and descending. Conclusion: Despite the user movement and seat angle change, MEBot maintained its stability as the center of mass remained over the wheelchair footprint when performing its mobility applications.

Integration of Pneumatic Technology in Powered Mobility Devices.

Advances in electric motors, electronics, and control systems have enhanced the capability and drivability of electric power mobility devices over the last 60 years. Yet, battery technologies used in powered mobility devices (PMDs) have not kept pace. Recent advances in pneumatic technology, primarily the high torque, low speed design of rotary piston air motors, directly align with the needs of PMD. Pneumatic technology has advantages over battery-powered technology, including lighter weight, lower operating costs, decreased environmental impact, better reliability, and increased safety. Two prototypes were created that incorporated rotary piston air motors, high-pressure air tanks, and air-pressure regulators. Prototype 1 was created by modifying an existing electric PMD. Range tests were performed to determine the feasibility of pneumatic technology and the optimal combination of components to allow the longest range possible at acceptable speeds over ideal conditions. Using a 1.44 L air tank for feasibility testing, prototype 1 was capable of traveling 800 m, which confirmed the feasibility of pneumatic technology usage in PMDs. Prototype 2 was designed based on the testing results from prototype 1. After further optimization of prototype 2, the average maximum range was 3,150 m. Prototype 2 is up to 28.3% lighter than an equivalent size electric PMD and can be fully recharged in approximately 2 minutes. It decreases the cost of PMDs by approximately $1,500, because batteries do not need to be replaced over the lifetime of the device. The results provide justification for the use of pneumatic technology in PMDs.

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.

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.