Conclusions:
Overall, we were quite satisfied with how well the mechanism performed. The final prototype met the following objectives that were outlined at the beginning of the project:
- Semi-circular path- ✅
- Non-constant velocity, fastest when returning to the pool- ✅
- Powered by singular motor rotating at a constant velocity- ✅
- Mimic appearance of inspiration artwork- 50%
- No larger than desktop sized- ✅
Here, it is noted that the mimicked appearance objective was only partially satisfied by our mechanism. This judgment was based on the limited effectiveness of the mechanism to actually scoop and pour water. Unfortunately, the swinging bucket design was not an ideal method of performing this task, and is noted in “future work” as an area of improvement.
Future Work:
For future iterations of the mechanism, we would likely revise the path of the end effector so that the actual pouring motion is facilitated without having to rely on a swinging bucket. We anticipate that this could be done with the same general linkage set-up currently being used but with adjusted pin locations and link lengths. Ideally, a rigid bucket and a more emphasized tipping motion by the end effector would be a more effective solution. Additionally, greater effort to waterproof the acrylic tank during the manufacturing phase would be needed to allow the mechanism to contain water for extended periods of time. Final Design:
Our final prototype is a four bar mechanism. The mechanism has three grounded pins, three manufactured linkages, two slots, and five rotational joints. We have the bucket attached to the end of our coupling linkage. We chose this position because it has the required motion and the space to attach a bucket to the end. This location allowed up to fasten the bucket without it causing interference between the other linkages. From our kinematic analysis the mechanism has one degree of freedom and meets our requirements presented in our design goals. Also from the kinematic analysis we were able to see that the present Coriolis acceleration is relatively low until the quick acceleration where it spikes for both slots, figure 3.8. The mechanism is powered by a single NEMA stepper motor running at a constant angular velocity. The Arduino code used is located in the appendix of this report, also figure 5.3. The total cost of of this project came out to be $76.62. A break down of the cost can be found in the Bill of Materials section of the appendix.
The video below shows our mechanism performing its desired task of collecting from the pool of water and dispensing it back into the capture tank.
Figure 6.1. Video of Operation