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.

Assessment of Usability and Task Load Demand Using a Robot-Assisted Transfer Device Compared With a Hoyer Advance for Dependent Wheelchair Transfers

OBJECTIVE

Manual lifting can be burdensome for people who care for power wheelchair users. Although technologies used for dependent transfers are helpful, they have shortcomings of their own. This study compares the usability and task load demand of a novel robot-assisted transfer device to a clinical standard when performing dependent transfers.

DESIGN

A cross-sectional study was conducted to assess caregivers (N = 21) transferring a 56-kg mannequin with the Strong Arm and Hoyer Advance at three transfer locations. Feedback was gathered through qualitative surveys.

RESULTS

Usability was significant in multiple areas important for transfers. Caregiver fatigue and discomfort intensity were reduced, and the Strong Arm was preferred at the three transfer locations. Device ease and efficiency favored Strong Arm at two stations as was discomfort frequency. In addition, physical demand, frustration, and effort were significantly lower using Strong Arm compared with the Hoyer Advance.

CONCLUSIONS

Compared with the Hoyer, participants favored Strong Arm for transfer usability and task load demand. However, further Strong Arm developments are needed.

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.

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.

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.

A perspective on intelligent devices and environments in medical rehabilitation

Globally, the number of people older than 65 years is anticipated to double between 1997 and 2025, while at the same time the number of people with disabilities is growing at a similar rate, which makes technical advances and social policies critical to attain, prolong, and preserve quality of life. Recent advancements in technology, including computation, robotics, machine learning, communication, and miniaturization of sensors have been used primarily in manufacturing, military, space exploration, and entertainment. However, few efforts have been made to utilize these technologies to enhance the quality of life of people with disabilities. This article offers a perspective of future development in seven emerging areas: translation of research into clinical practice, pervasive assistive technology, cognitive assistive technologies, rehabilitation monitoring and coaching technologies, robotic assisted therapy, and personal mobility and manipulation technology.

Influence of Wheelchair Front Caster Wheel on Reverse Directional Stability

The purpose of this research was to study directional stability during reversing of rear-wheel drive, electric powered wheelchairs (EPW) under different initial front caster orientations. Specifically, the weight distribution differences caused by certain initial caster orientations were examined as a possible mechanism for causing directional instability that could lead to accidents. Directional stability was quantified by measuring the drive direction error of the EPW by a motion analysis system. The ground reaction forces were collected to determine the load on the front casters, as well as back-emf data to attain the speed of the motors. The drive direction error was found to be different for various initial caster orientations. Drive direction error was greatest when both casters were oriented 90 degrees to the left or right, and least when both casters were oriented forward. The results show that drive direction error corresponds to the loading difference on the casters. The data indicates that loading differences may cause asymmetric drag on the casters, which in turn causes unbalanced torque load on the motors. This leads to a difference in motor speed and drive direction error.