For this third round of prototyping our team wanted to focus on making a more ergonomic and fully functional design. In this prototype the team wanted to focus on:

• Making the seat more ergonomic and softer
• Improve handle design, to be stronger and more appealing to the eye
• Ensure the bearing/platform of the seat can support more weight
• Improve the foam on the bottom of the seat so taller people can also use the seat
• Find a way to move the handles/seat more adjustable
• Make a more user appealing prototype

The team took this considerations into place and met with Ohio State’s Kevin Wolf to get additional design opinions and input. Ideas such as using a compressor/air, using one handle, using one locking mechanism, and materials were all discussed. After this design discussion the team began redesigning the handle bars and locking mechanism. For this prototype, the handle bars were redesigned to add adjustability vertically. Initially, the team thought about horizontal adjustment, but realized that in a car space this was not a possibility given room in a seat. To improve the horizontal dimensions of the seat to allow for a more user friendly device for all people, the team moved the handles so they were out wider on the base on flanges. Additionally, to improve space, the locking mechanism was moved to the side of the seat base so it would not affect user movement or space. As a result of this locking mechanism movement, the base also had to be redesigned to accommodate such locking and was configured out of layers. Finally, to improve ergonomics, the under base cushion was changed from solid foam to a shredded foam and a seat cover was also to be added for comfort.

The team first modelled the idea in Solidworks intending to use both stock parts and 3D printed parts. Images of the Solidworks rendering are shown below. Note that these drawings to not include the seat cushions.

The prototype was then assembled by the team. Pictures of this assembled product are shown below.

This prototype was then tested with three people in three different cars. Pictures of these tests are shown below. Here are the results of these tests:

• all three people fit in the seat, but one person did express it would have been nice to have more room
• the seat rotated well, but the handles hit the back of the seat, stopping full rotation
• seat was too tall for shorter cars, causing people’s heads to be at the ceiling

This prototype was presented to a stakeholders including an occupational therapist with the main feedback being:

• ensuring that the base is big enough to support all individuals even those whose hip width might exceed the seat cushion
• wondering if the armrests could be height adjustable while still maintaining their sturdiness. To address these concerns, in future iterations, the team

To address these concerns, in future iterations the team wanted to make sure that the whole arm rest could be detachable to allow for easy removal from the seat base in the case that more room is needed and increase the seat base to its maximum value by moving the handle plungers to the back. Lastly, the team wanted to add more support to the plungers used within the handle, to add extra strength to the design.

After receiving feedback on the prototype from the class, in this prototype round we wanted to focus on how to attach our seat to the base securely and how to lock the seat from rotating. The questions we wanted to answer were:

• How do we want to lock and unlock the seat when rotating?
• What is the best way to adjust for angles and unlevelness of car seats?
• How can we attach the device to the car seat?
• What mechanism can we use in the handles so they can move efficiently and are easy to use?

The team brainstormed ways to lock the seat in place with the handles. Below are the initial design ideas. The idea the team decided to pursue involved putting holes into the base for a pole to fall into, thus locking the seat rotation. This pole would be a part of the handle design. One part of the handle would involve the pole, two stoppers, and a spring in between. One of the stoppers would be encapsulated in the base of the handle with the other exposed to pull up on and the spring to help guide the pole into a hole. As the user rotates they hold up on the lower stop and release to lock it.

For the attachment to the seat, the team wanted to use a buckle and straps. To connect it to the seat, the team had the idea to add slits to the base of the seat platform through which the strap could feed. It could then be buckled around the seat.

The team took these ideas and mocked up the whole prototype in solidworks. Images of these mockups can be seen below and feature the whole handle mocked up with a rod, ceiling flange pieces as the stoppers, a spring, handle encasings to be 3D printed and the base with holes. On the base these slits can also be seen.

The team aimed to 3D print the handle encasing and to laser cut the base and seat. Every other part was to be purchased from stores. Additionally, thick foam was bought to be added to the base of the seat to allow for more molding to the seat bucket.

Unfortunately the 3D printer could not finish in time, so the handles had to be made out of wood for this round. The same mechanism was able to be constructed. The final prototype is shown in a car below.

From sitting and trying out the seat, the team realized the foam purchased may be too thick for fitting in the base and not adding too much additional height. Additionally, the team realized that the seat and handle dimensions are small and not adequate for a variety of people, therefore more adjustability needs to be added to the design. Finally, when testing the rot0tating structure under human weight, the team realized they may need to add spacers or extra support so the top seat does not fall too close to the base, making it hard to turn/lock.

From the class, the team received the following feedback:

• Consider when you sit the way that the base and swivel seat touch, look at putting spacers in
• Potentially use a bean bag  instead of thick foam for under the seat
• Look at amperometric data for what width a seat should be
• Look into using one handle that is detachable/moveable depending on the side you are on