Lessons Learned
In the process of constructing and refining a mechanism, there is a lot learned from engineering as well as people. There is a manufacturing component and a theory implementation component(code and dynamics) to this project. Quickly, we realized that each group member had their own strengths. Dividing the work adequately was something we did very successfully to aid in the completion of this project. Each member worked on what they were best suited to, and the team made progress overall. Additionally, time management was key. We often had to work around the operational hours of TIW and that presented time conflicts with the rest of our availability. Furthermore, something we realized a bit late into the project was that we spent just as much time thinking of solutions to our problems as we did making parts.
The engineering portion of the project taught us a great deal. First, dealing with tolerances proved to be a considerable challenge, requiring extensive trial and error. We gained familiarity with the tolerances associated with various manufacturing methods such as laser cutting and 3D printing. Ample time for testing was essential to achieving desired press fit or shaft sliding functionality. Also, material selection played a pivotal role in the prototyping phase. Laser cut plywood and 3D printed PLA/PETG proved beneficial for their adaptability to filing and drilling. We gravitated towards these because of their availability and versatility. However, issues arose as the project progressed. The wood introduced friction and also deteriorated, prompting the realization that better materials, such as smoother acrylic gears and metal shafts, could have enhanced the overall performance of later prototypes.
Another lesson had to do with the detriment of cantilevered shafts. Even though these shafts didn’t necessarily contribute to the mechanism’s functionality they affected the project’s rigidity. If there is not adequate support, then the mechanism will not execute its goal properly. Beyond this, stacking was something new to us. When the mechanism was designed in SolidWorks it was flush and perfect. However, when we made the components, we realized that there was friction we didn’t account for and spacing conflicts that made the mechanism collide with itself. If we had known about this, earlier we would’ve incorporated small shims into the linkage stack as well as spacers. For the motor, there are ways to configure it to get the exact output required. Design oversights, such as the lack of a designated space for the battery and delayed implementation of strain relief for the wires, highlighted the need for better foresight in future iterations. Undoubtedly, the importance of strain relief became evident as wires consistently detached from the motor, leaving the team without a means of reattachment when TIW was closed.
On the design front, a valuable realization was that the linkages themselves could take on various shapes, provided the joints were appropriately positioned. This flexibility allowed for customization of the shovel link to better suit the specific requirements of the project. Initially, we made a 6-bar linkage that was used in our prototype. We were told that we could treat our 6-bar linkage as a 4-bar linkage and create the links to be whatever shape we wanted to meet the needs of the robot. By following this advice from the judges on prototype demonstration day, we were able to create the maze within our linkages for the seed to drop out, as well as a better way to incorporate our shovel head without spacers. Overall, the construction and design process involved a dynamic interplay between material choices, mechanical considerations, and iterative adjustments, emphasizing the importance of adaptability and continuous improvement in engineering endeavors.
Image of our prototype as six linkages on the left. Image of our final prototype as a four-bar linkage with our red maze in between the links.
Tips for Future Groups
Starting early is essential for the project. Your first idea might not be adequate when executed so go to the TAs as many times necessary, so you have a solid and precisely defined idea to launch. The time for the completion of this project will be at least twice what is expected. Additionally, make sure to take advantage of operational hours in TIW and ask anyone for help when needed.
Acknowledgments
Ashwin, for advice with bearings and shafts, donating his shafts, rubber bands, belt advise for tensioning, soldering our motor wise at 1am (legend)
Victor, laser cutting our links for build assignk,emt. soldering our motor wires right before demo
Professor Rohit John Varghese, for being encouraging and making us feel supported at all times and teaching us such complex topics.
Sid, for pushing us to think critically about the 'why' of every aspect of our project. We are better problem solvers and engineers because of you.