09.7 Conclusion
Project Overview and Outcomes
This project was meant for us to set out and design a cat toy mechanism that could entertain Tong’s cat while she is busy and not able to give her full attention. The overall idea was to have a robotic arm mechanism that flicked up and down, mimicking the motions of what cats normally find fascinating when playing with toys while also be drivable on a moving base.
Some of the original objectives were achieved, such as the arm’s flicking motion. A brushed motor was successfully used to drive gears that moved sliders within the linkage, allowing the tip of the arm to move rapidly up and down. However, other objectives were not fully met. The arm’s tilt control was limited by insufficient static torque from the servo motors, preventing stable up-and-down positioning. With this, we also could not get the car-base to move because if the whole mechanism moves with some velocity, the arm won’t be able to stay up.
Additionally, the broader goal of keeping the cat entertained was only partially achieved, as the size and noise of the mechanism occasionally scared the cat and caused it to run away.
Lessons Learned
One of the main lessons learned was time management. When we would go to work on the project, we knew we had to be efficient to not take a long time in reaching our goals throughout the project. This meant from working and finishing CAD models as well as 3D printing since Texas Inventionworks has a 5 hour print policy and it is normally busy during the week with other students. We had to work with each other’s busy schedules to find times to meet and make sure everyone is on the same page in the design process.
Several technical skills were developed and strengthened, particularly CAD modeling in SolidWorks. Identifying and resolving interferences before printing was critical to efficiency, as the parts were large and time-consuming to reprint. In addition, we gained experience applying appropriate tolerances for different components, such as bearings and shafts, to ensure proper fits without being too loose or too tight. Ben also created a test model with varying hole sizes, which allowed us to determine the correct tolerances and proved helpful throughout the project.
Teamwork was another major skill that improved throughout the project. Leveraging each member’s strengths while supporting weaker areas helped the team work efficiently and stay on track. Observing how others approached electronics and CAD design in SolidWorks also allowed everyone to learn new techniques, ultimately strengthening each member’s overall engineering skill set. Also with each member being involved in other campus organizations and several classes, we had to adapt to each others schedules and effectively communicate to make sure that we kept our pace which was also key for each person’s overall understanding of where we were on the project.
Future Work and Design Improvements
There are several major improvements that could be made to make the robot better:
Change the servos that are used to control the tilt to have a higher stall torque to ensure that the tilt link didn't just fall after a certain amount of movement
Decrease overall size of the robot to make the parts lighter on the electronics and allow for greater accuracy
Use closed loop response to control the motors and servo so that we can tune the motion to be consistent controlled velocity during any angle of the mechanism
Switch gears to from spur to herringbone to decrease noise and vibration which would overall decrease the potential to scare the cat
Increase the gear reduction from the motor to the 360 degree linkage so we can have finer control and not get stopped by mechanical losses like gravity and friction
Cosmetically tune the colors of the prints to match ones that cats can see more vibrantly like blues and yellows to increase engagement
Advice for Future Groups
For future groups planning on working on this project or something similar, some tips are to make sure that you use your time wisely. This kind of project can seem simple, but the complexities will start showing up and it can start to get difficult when troubleshooting and problem solving. Also, try to scale down the model when prototyping to make sure that you can get the movement you want without having to use up so much time and material.
A common issue that we ran into was when working with the electronics. Some of the issues were simple fixes but the group needs to be able to think creatively because the solutions aren’t always straight forward and to also understand the equipment that you are using. For example, when we encountered issues, it would be a discussion of whether it was a hardware or software issue, and if we knew the details of the components that we were using a little more, then we could have saved some more time when assembling.
Another recommendation is to use collaborative software, such as Bild, to manage and track updated CAD files. Harshit introduced this tool to us, and it significantly improved our workflow by allowing us to see who edited each file and when changes were made. Since SolidWorks does not support multiple users working on the same file simultaneously, this approach helped reduce version conflicts and improved overall coordination.
Acknowledgements
We would like to give thanks to those who helped in our project:
Dr. Christina Petlowany - Helped guide our initial ideas and gave good feedback on what we can improve on
Cade Wetherill and Min-Geun Park - For always being available when we needed help whether is was software or hardware issues
Texas Inventionworks - For giving us the resources and tools to be able to create our project such as laser cutters, soldering kits, 3D printers, etc.
Harrison Floyd - For helping us 3D print our pieces whenever we couldn’t be able to make it to TIW during the day or if parts would take longer than anticipated.
Nathan Walsh - Helping us when assembling the robot giving us answers as to why certain parts, whether electronics or hardware, were not working as they should.