2.6 - Conclusion and Future Work
During the day of demonstration, the tabletop basketball machine was able to adapt and become a tabletop ball game machine that demonstrated the ability for a motor to achieve a catapult motion without a capacitive element such as a spring or rubber band to launch a ball. With an adjustable launch angle, manual fire mode, and automatic fire mode, it was successful in making tabletop ball games more interesting by introducing a new level of skill by requiring the user to become proficient at operating the catapult.
Kinematic analysis showcased the increase in angular velocity at the launch angle, and showcased the fact that a purely mechanical design can create varying speed outputs based on a constant input. The mechanism designed was able to take an input of 100 rpm from a motor and increase it by 1.5x for a brief period of time at the launch angle to achieve the speeds necessary to launch a projectile.
Lessons Learned:
While the mechanism was successful in launching a ball, there were a couple key issues created lot of difficulty throughout the project:
Build Quality- There was a massive amount of friction in the first couple final iterations of the mechanism that caused the motor to struggle to drive it at the launch point, preventing a full rotation of the crank shaft. This required us to rebuild the mechanism again, this time taking heed of the alignment and tightness of the screw joints. One should always take care to be precise when assembling things in order to ensure that a good design does not get hampered by poor build quality.
Motor Strength- The motor we chose was not strong enough for the mechanism as we did not have a good sense of how much torque is required to ensure smooth, continuous motion through an entire rotation of the crank shaft. Proper consideration of the output torque and voltage requirements is of upmost importance instead of just assuming that a motor would work.
Sense of Scale- For the initial design, some material was wasted as viewing the mechanism in CAD or the links in the laser cutting software does not easily reveal their true scale in the real world until fabrication began. This meant that being careful about the units of dimension in software is important to prevent the mismatch in size.
Tips for Future Groups:
From the lessons learned above, we recommend future groups consider the following advice:
Spec motor well – always error on the side of safety when it comes to motors
CAD early and test often – sometimes cramming for a project is inevitable, but earlier testing and design and persistent effort makes it much more manageable. Testing and prototyping reveals oversights that CAD may not have been considered during design.
Attention to detail – Better build quality and attention to detail would have saved us a lot of headache during testing. We thought our design was flawed, however there was just a lot of friction in our build from making joints too tight.
Future Work:
Variable Motor Speed Output - Future iterations of our launcher could include programming the output desired speed of the motor to control how fast / far the ball goes when launched. The current design only has one motor output speed, but a simple arduino program adjusting the motor RPM could add a new layer of complexity and variation to our game. This could be implemented discretely using a button as the input, or analog using the current joystick implementation.
Other improvement ideas:
Bearing integration (replace screw joints with bearings)
Automated scoring system
Moving hoop
Acknowledgements:
We would like to use this section to explicitly thank everyone who helped us in the process of building this project. Specifically, we are very thankful for the feedback and guidance from Dr. Symmank, as well from grad students Min-Guen and David during our weekly project meetings.
We also would like to thank Texas Invention Works for the extended project resources and assistance from staff members.
Thank you for reading our wiki! We had a fun time working on this project.