RESNA Annual Conference - 2019

OverShield: A Powered Wheelchair Umbrella

Tarek Midani, Devin Bonner

University of Alabama at Birmingham - Master of Engineering in Design and Commercialization

1. Problem and Background Need Statement

Currently, there is still a need for a way to provide powered wheelchair users rain protection without impeding normal transportation and without requiring upper body dexterity, allowing users to be independent and mobile.


Although mobility device users represent only a relatively small minority of the population with disabilities, we think their importance transcends their numbers. Mobility devices, especially wheelchairs, are visible signs of disability and have become symbols in themselves of the very idea of disability. Understanding the magnitude and characteristics of the population using assistive technologies is therefore important before designing a product and addressing their needs.

With an average of 139 rainy days per year in Toronto [1], and 167 days in New York, that’s more than a third of the year when an umbrella is needed for users of powered wheelchairs (PWUs) especially since any kind of rain can short the circuit in their wheelchair controls and cause extreme discomfort, or at the least, it will reduce independence.

Our device will target users of powered assistive mobility devices, with approximately 127,000 powered wheelchairs sold in the U.S. annually. [2]

Conditions Leading to use of powered wheelchairs with the accompanied US statistics

  1. Quadriplegia from SCI 128,000 [3] = 45% of 285,000

  2. Cerebral Palsy (LVL 4 & 5) 224,000 [4] = 30% of 764,000

  3. Multiple Sclerosis (Primary) 100,000 [5,6] = 25% of 400,000

  4. Muscular Dystrophy 45,000 [7]

  5. Parkinson’s Disease

  6. Huntington’s Disease

Therefore, the estimated number of users of Powered Wheelchairs is about 500,000 people in the US alone [A].

Some of these diseases occur at a later age such as Huntington’s and Parkinson's. While the other conditions are not age specific, for example Cerebral Palsy, starts at birth and is a genetic disorder that affects people throughout their lives. It is the most common motor disability in childhood [14] and in the United States it affects 764,000 children and adults [16]. However, the severity of cerebral palsy ranges greatly. Individuals with higher severity classification (GMFCS level 4 & 5) are usually wheelchair bound and can potentially benefit from our proposed device.

Besides neurological disease, spinal cord injuries (SCI) is the second most leading factor that contributes to the number of PWUs after CP. According to a report from the National Spinal Cord Injury Statistical Center (NSCISC) [17], approximately 12,500 people per year are affected by a spinal cord injury in USA. There are between 250,000 and 500,000 new spinal cord injury cases every year worldwide [18].

2. Solutions Considered

In our master’s project our team have explored many different alternative solutions to this problem. Below are some solutions with their summaries

Directed Air Fan

Mounted air blower “umbrella” on the headrest being adjustable by servo motor, device will blow the air and rain away from the rainy come from every angle of rain.

Pros: Easy to mount
Cons: Energy drain on the wheelchair battery and noise. Also, the device is not perceived to be reliable regardless of whether it is reliable or not.

Convertible-Like Cover

Dividing the rain cover into three pieces that collapse over each other. The function of the middle piece is to be the attachment point for each part of rain cover, and the third part will be the connection to back side of the powered wheelchair to collect all of the rain covers into backpack- like package behind the wheelchair.

The reason we’ve explored this option is because of the importance of the compactness of the umbrella when it is collapsed and not in use. After receiving feeding on the first prototype being bulky, we’ve realized that wheelchair users (both manual and powered) do not want to be attached to a gimmicky device that makes them stick out like a sore thumb. Rather, they want to be seen as normal everyday people.

Pros: Compactness, Efficient Deployment Cons: Cost of manufacture

Custom Sized Ponchos

Sometimes the best solution is the simplest. There are many custom poncho solutions that are meant to be custom tailored to the user, this solution is the only viable thing on the market due to its low cost. However, it suffers from the same problems we are trying to solve: it can’t be deployed on demand, unreliable in the wind. And water could easily float inside. Not to mention that wearing it for individuals with powered wheelchairs often requires the assistance of the caretaker.

3. Description of Final Design

The wheelchair umbrella, called OverShield, is a compact product that includes an attachment to the powered wheelchair. This attachment will adapt to multiple brands of powered wheelchairs like the Permobil wheelchairs.

1. Attachment

In the case of the Permobil, the device will attach to its new modular link hardware of 7”, 10”, or 14” widths which is used to mount a headrest and other attachments. Aluminum keys will run the length of each link and interlock with those of the next link to maximize surface contact and ensure joint stability.

Other powered wheelchairs most commonly used include Invacare which include the TDX and Storm lineup. And at the lower-end you have manufacturers like Pride Mobility with the Quantum lineup which offers good value, and the Jazzy which is colloquially known as a “scooter” rather than a wheelchair. Each of these wheelchairs will have a slightly different attachment gadget. With the Quantum attachment location shown in Figure 2.

2. Vertical Lift

The ability to lift vertically the umbrella into proper position is crucial to allow the umbrella to be compact when not in use.

The vertical lift will be connected to the attachment and on the other hand connected to the umbrella frame. It will mainly consist of a high-speed linear actuator capable of a speed 5.51”/sec and a force of 22 lbs., with a stroke of 16 inches.

It will be controlled using a SparkFun RedBoard, programmed as an Arduino board. And initiating the deployment will be a easy-to-press button.

3. Wheelchair Frame

For the skeleton structure of umbrella, we select the Easy-to-Weld 4130 Alloy Steel Round Tube of 0.035" Wall Thickness, 1/4" OD [24] which we will be requiring 18ft

a wheelchair umbrella frame, and a wheelchair umbrella cover. An actuated motor raises up the wheelchair umbrella frame and deploys the wheelchair canopy (90°). It is mounted before there is a need to use it but will usually be collapsed behind the back of the wheelchair.

4. Outcome

The new OverShield prototype is in the fabrication process and will be completed by the conference dates. We have, however, talked to several customers about what they would like to see happen with a product of this caliber, have based our design off of the feedback as well as the feedback from a previous prototype. With this prototype we will be evaluating the umbrella under severe weather-like conditions, i.e., high windspeeds, and rain. Also, a strength test will be conducted to test the durability of the product.

5. Cost

From speaking with over 20 excited users of the powered wheelchair idea, we’ve asked what would be the optimal price range that is optimal or expected.

We found that for some users, they expressed having less disposable income due to what we call the “disability tax” where even though the average working user of powered wheelchairs makes comparable income to the average American, they have more expenses due to their disability. Expenses ranging from paying more for medical insurance, to more costly vehicles, and paying for 20% of the cost for DME’s (durable medical equipment) since Medicare Part B covers 80% and only for what’s deemed necessary. Most PWU opt for additional features that increase their quality of life like power standing.

Due to all this the cost of our product will be at 400 USD, with options for 300 USD possibly available.

6. Significance

Millions of people with disabilities regularly travel, shop, and eat out with family and friends. According to Census 2000, approximately 20.9 million families in the US have at least one member with a disability. [20]

Powered wheelchairs are used over manual wheelchairs for a variety of reasons depending on the user's physical strength, dexterity, and distance. The benefits of power mobility include increased activity levels and social participation [10-13]. Which is why there is a gap in the market addressing not having the upper dexterity to carry a traditional umbrella or deploy a manual one.

According to Transparency Market Research, the global power wheelchair market sees an Annual Growth Rate (CAGR) of 19.2% projected for 2014-2020. As of 2015, the global power wheelchair market was $1.6 million and is expected to grow to $4.85 million by 2022.

North America is the center of power wheelchair manufacturing with its multiple established manufacturers, high amount of disposable income, and high consumer awareness. Invacare Corporation, Permobil AB, Pride Mobility Corp, and Sunrise Medical Limited are some of the major companies that make power wheelchairs [19]. Customers who stand to gain the most from a new automatic solution are those who do not have a caretaker or who live alone. This group is expected to grow in the coming years, as the ageing population rises, and technology allows people more freedom to do daily tasks from their wheelchairs.

All wheelchair users rely on imperfect weather protection methods during transportation from point A to point B whether that is from work to vehicle or from house to a destination. Our device, a self-deploying wheelchair umbrella, will be designed to solve this problem. The main purpose is to make the wheelchair user feel independent and be in control during inclement weather. It will increase the quality of life for the user’s families as well. Additionally, the powered wheelchair umbrella will also encourage those who have limited mobility to be more active and more productive, benefiting the individual and the society as a whole.




  3. DeVivo, M. J., et al. (2002). "Overview of the national spinal cord injury statistical center

    database." The journal of spinal cord medicine 25(4): 335-338.

  4. Yeargin-Allsopp, M., et al. (2008). "Prevalence of cerebral palsy in 8-year-old children in

    three areas of the United States in 2002: a multisite collaboration." Pediatrics 121(3): 547-


  5. Dilokthornsakul, P., et al. (2016). "Multiple sclerosis prevalence in the United States

    commercially insured population." Neurology: 10.1212/WNL. 0000000000002469.

  6. Devitt, R., et al. (2004). "The effect of wheelchair use on the quality of life of persons with

    multiple sclerosis." Occupational Therapy in Health Care 17(3-4): 63-79.

  7. Chiriboga, C. A., et al. (2016). "Results from a phase 1 study of nusinersen (ISIS-SMNRx)

    in children with spinal muscular atrophy." Neurology 86(10): 890-897.

  8. Pettersson, I., G. Ahlström, and K. Törnquist, The value of an outdoor powered wheelchair with regard to the quality of life of persons with stroke: a follow-up study. Assistive

    technology, 2007. 19(3): p. 143-153.

  9. Davies, A., L.D. Souza, and A. Frank, Changes in the quality of life in severely disabled

    people following provision of powered indoor/outdoor chairs. Disability and

    Rehabilitation, 2003. 25(6): p. 286-290.

  10. Frank, A., et al., Introduction of a new NHS electric-powered indoor/outdoor chair

    (EPIOC) service: benefits, risks and implications for prescribers. 2000, SAGE Publications

    Sage CA: Thousand Oaks, CA.

  11. Brandt, A., S. Iwarsson, and A. Stahle, Older people's use of powered wheelchairs for

    activity and participation. Journal of rehabilitation medicine, 2004. 36(2): p. 70-77.

  12. Salminen, A.-L., et al., Mobility devices to promote activity and participation: a systematic

    review. Journal of rehabilitation medicine, 2009. 41(9): p. 697-706.

  13. Löfqvist, C., et al., Mobility and mobility-related participation outcomes of powered wheelchair and scooter interventions after 4-months and 1-year use. Disability and

    Rehabilitation: Assistive Technology, 2012. 7(3): p. 211-218.

  14. Accardo, P.J. and A.J. Capute, Capute & Accardo's Neurodevelopmental Disabilities in

    Infancy and Childhood: Neurodevelopmental diagnosis and treatment. Vol. 1. 2008:

    Brookes Pub.

  15. Arneson, C.L., et al., Prevalence of cerebral palsy: autism and developmental disabilities

    monitoring network, three sites, United States, 2004. Disability and health journal, 2009.

    2(1): p. 45-48.

  16. Yeargin-Allsopp, M., et al., Prevalence of cerebral palsy in 8-year-old children in three

    areas of the United States in 2002: a multisite collaboration. Pediatrics, 2008. 121(3): p.


  17. White, N.-H. and N.-H. Black, Spinal Cord Injury (SCI) Facts and Figures at a Glance. 2016.

  18. Dilokthornsakul, P., et al., Multiple sclerosis prevalence in the United States commercially insured population. Neurology, 2016: p. 10.1212/WNL. 0000000000002469.

  19. Verma, P. (n.d.). Electric Wheelchair Market by Product type (Centre Wheel Drive, Front Wheel Drive, Rear Wheel Drive, Standing Electric Wheelchair) - Global Opportunity Analysis and Industry Forecast, 2014 - 2022. Retrieved October 01, 2017, from

  20. U.S. Census Bureau. “Disability and American Families: 2000.” July 2005. < (7 April 2006).