Building an Adaptive Tennis Racket for Weakened Grip Strength

Samy Ismail, Hunter Li, Maxine Lui, Tyler Washington, William Weninger, and Nick Yang

Intro

We are the Racket Scientists! Our goal for this past school year was to build a device that would help people with contractive fingers and limited wrist mobility to comfortably participate in wheelchair tennis. After observing a wheelchair tennis practice, we saw that there was a need to develop a device that is reusable, sturdy, and easily adjustable throughout a practice session. While our clients had limited wrist mobility, they are able to freely move their shoulders and elbows in any rotational angle desired. Therefore, there was a need to develop a structurally sturdy device that would allow wheelchair tennis players, who cannot firmly hold a racket, to comfortably perform basic tennis movements without constricting the upper arm extremities.

Research Poster

Community Partner

Our community partner is UMAISE, which is an organization that provides opportunities to people with disabilities to participate in various sport and recreational activities. In particular, we worked with the wheelchair tennis coordinator, Seong-Hee Yoon. The player we specifically worked with is Molly. Molly had contractive fingers, which meant that she was not able to physically hold a racket to play. However, she was able to freely move her arm with little to no limitations.

Market Research

Our market research took place at the beginning of our project. To start the process, everyone tried to find as much information as they could about adaptive tennis and the various devices that are used. After coming back together with all of the information that we found, there did not seem to be many solutions used to assist in holding the tennis racquet other than athletic tape. One possible product that was found that could be used to help grip the racquet is a grasping cuff. However, downsides that come with it are a lack of adjustability for the racquet (the angle and length it’s held at), as well as a lack of wrist support, which can lead to wrist stress or injury. One benefit that does come with these grasping cuffs is that they are lined with dycem. Dycem is a sticky material that can be used by the players to assist in pushing their wheelchair while playing. Other than this product, a few of the adaptive tennis organizations seemed to have made their own devices to help with gripping the rackets, but there is not any adaptive tennis racket that is currently being mass-produced.

We also attended our community partner’s practice and gathered some more information by talking to some of the players. Again, the overwhelming solution that was used at their practice to assist in holding onto their rackets was athletic tape. A prototype was made by our community partner that was being used by one of the players. However, a few downsides came with this prototype, including a lack of adjustability (again in terms of angle and length), the creation of waste (a disposable wire tie had to be replaced every time the racket was adjusted), and a lack of breathability where the device was attached to the arm. We looked to take all of these observations into account while designing our own adaptive tennis racket.

Concept Generation/Solution

Our design process spanned over two semesters where we worked on developing a functional prototype during the first semester which allowed us to modify our device to better suit the clients needs in the second semester. We began our brainstorming by inspecting critical features of our clients original device (a plastic plate with simple straps) that were limiting the ability to play tennis conformably. This led us to a couple key design features that were necessary to provide an optimal playing experience: adjustability along the users forearm, straps to tighten the device against the arm, comfortability while playing, lightweight, and some other smaller requirements highlighted on the table on the poster above. We addressed our main concern, adjustability, through a sliding bar track similar to a lock that travels down a track. Additionally, we intended to create metal plates to support the sliding track and this is where the idea came together; straps would be used to mount the foam encased device around the arm while screws would be used to assemble the adjustable sliding track that was mounted to the arm. Our process involved careful selection of materials while developing the prototype, which led us to using aluminum, a lightweight yet durable metal, and adjustable zip ties to mount the racket to the metal sheet. The sliding track and plate assembly was modeled through CAD.

Prototype

The prototype fits all the functional requirements but still has some work to do on it’s overall aesthetic. The device requires no more than 5 minutes of application and fitting time. It is extremely easy to apply and easy to take off. With more time we would duplicate the prototype aerate it, file it and add some more appealing finishings to be used by our community partner.

Challenges

Our team faced a number of challenges as we progressed through the design process. The biggest challenge our team faced was the fact that the community partner we worked would only have practices once a month. This meant that we had trouble getting consistent feedback on our design. We were able to get feedback over email but a lot of good insight would have come from watching the players use the device and having feedback from people using the device as intended. We were able to get some feedback from a tennis team that a few of our members were part of to get some user feedback. Another challenge that we faced was having our entire team involved with the project and having people held accountable for completing different aspects of the project. Something the team was planning to do was split up into different sub teams that were responsible for improving different aspects of the prototype. Unfortunately we weren’t able to implement this strategy for very long because of the Corona virus but it would have helped the members of the team have something to be accountable for.

Feedback/Future Plan

Testing our device was another challenge in itself. Due to how few the number of practices UMAISE held, it was difficult to arrange a time where all of us could travel to the Varsity Tennis Center and test our prototype with our community partner. However, before the pandemic occurred, we were able to meet with UMAISE once and get some feedback from Seong-Hee. It was overall a positive experience; we gained valuable insight on improving our design. Unfortunately, we were unable to test the design with our MedLaunch product design specialist at the time. To try to get that physical feedback from actual tennis players, we sought some Club Tennis members and went to one of their practices in order to obtain some actual testing. Overall, the feedback was positive, with around 3–4 players being highly interested in the prototype. All of the participants noted how sturdy structurally the design was, and how stable the prototype was to the arm. Every player was able to perform high level movements such as a forehand and a one-handed backhand without any problems. They also mentioned that the device was comfortable in its current state, to our surprise. However, the most common feedback received was that the racket was too loose and was slightly wobbling in the zip-ties. This was expected, as we are still thinking about better ways to secure the tennis racket to the rest of the device. That leads to What’s Next? How are we going to proceed with the project, once this lockdown is over with (hopefully soon). First thing we’ll do is to 3D-print our new sliding tracks. We already designed new plates with alternating holes on them to allow for a rotational aspect about the arm. So this would give us a sliding and rotating movement on the device. This would also make it a lot less heavy, which would be good for everyone who wants to play with it. Next we want to better implement dycem, the sticky material. It is important to us that while the wheelchair tennis players can play tennis, it is also just as important that they retain their ability to maneuver around the tennis court. Adding a separate dycem design would help accomplish that. And lastly, to address the loose racket issue, we have been playing around with this tightening mechanism that uses metal string and a tightening knob. It’s similar to the stuff found on knee braces used by people with knee injuries. We haven’t really come up with a design for that yet, but hopefully, we will be able to resume our progress and continue to work with UMAISE. But first and foremost, stay safe, stay healthy, and practice social distancing! :)

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