Innagural Prototype
To begin the synthesis of a linkage to accomplish our goals, we turned to the aerospace industry for inspiration. We found that at the very least, the overall design of the modern "hide-in-armrest" tray table on airplanes mimics the function we strove to accomplish ("Center console stored extensible tray table" US Patent 6347590 B1). In our case however, we felt that it would be best to, if at all possible, keep our mechanism in a single plane. Thus, instead of folding back such as in Fig. 4, we choose to implement a rotation around our armrest-axis.
With the goals of the project in mind, the purpose of the team’s first prototype was to design a linkage that could move the table in the desired motion. The driving of the linkage via a motor and incorporation of the table mechanism into a walking device would be reserved for the final prototype. To begin, the team used existing mechanisms, such as the one pictured above in Figures 1-4, to establish a base design. Then, using Solidworks, the team began to add and remove links to slowly form a linkage producing the desired motion. The CAD model of the original linkage can be seen in Figure 5 below.
Figure 5: CAD render of the initial prototype.
With an established CAD model, it was then time to build our first working prototype. The team decided to use wood as a quick and inexpensive way to provide a proof of concept for our linkage. The entire first prototype, seen in the video below, was crafted in the ETC 6th floor Wood Shop using the band saw, table saw, scroll saw, drill press, and tool kits. The team used bearings and steel shafts along with the wood in order to ensure a realistic preview of the motion of the linkage. After finishing the prototype, the team identified several areas for improvement that would be implemented in the final prototype. A list of improvements is shown below.
Designated Items for Improvement in Final Prototype:
- Reduce footprint of mechanism in folded position
- Increase stability of table surface
- Eliminate large gaps in table surface
- Get rid of several interferences between links
- Improve craftsmanship through more precise manufacturing methods