Final Project Questions¶
Project Directions:¶
- Your project should incorporate 2D and 3D design, additive and subtractive fabrication processes electronics design and production, embedded microcontroller interfacing and programming, system integration and packaging.
- Where possible, you should make rather than buy the parts of your project.
- Projects can be separate or joint, but need to show individual mastery of the skills, and be independently operable
What Will It Do?¶
My final project will be a tennis ball machine that will launch tennis balls from the other end of a tennis court, which is 78 feet long. So, it will need to at least be able to launch balls for around 60 feet in order for it to be usable. The spin and speed of the ball will be adjustable (top/down spin). However, the direction will not be able to be controlled as I think the process of designing a rotating base will be too complex. It can also launch balls for dogs to play fetch.
Who’s done what beforehand?¶
After researching, I found this page on Instructables, which is a popular DIY website. This webpage has been really helpful in the designing process of my ball machine, as it gave me the idea of building an L-frame for the outer body of the ball machine. It also encouraged me to think more deeply about how the wheels are going to be turned by the motors. All of these will come later in my Final Project Documentation page. You can check out more about previous research here.
What will you design, and what processes will be used?¶
After meeting with Dr. Taylor, I created the following table in regards to what I will be designing as well as each process.
| Design Part | Process | Description |
|---|---|---|
| PCB Milling | Subtractive Fabrication | I will use a desktop CNC machine to mill out a copper board containing the board design created in KiCAD. |
| KiCAD | Electronics Design (2D) | A schematic and pcb design allowing my tennis ball machine to function. |
| Soldering | Electronics Production | Assembling the milled out copper board. |
| RP 2040 | Embedded Microcontroller Programming | Writing code for the embedded Raspberry Pi Pico in Arduino IDE. |
| ON/OFF button | Input Device | An independent button (NOT one that shuts off the power) embedded into the microcontroller programming |
| DC Motors | Output Device | These are attached to high-friction wheels that launch the tennis balls |
| Supports/Joints | 3D printing (additive) | Custom-made connecting parts for various places in my project |
| Enclosure | Laser Cut (subtractive) | To be placed around the ball machine in order to cover the electronics |
| Stand | CNC Machining (subtractive) | To be placed under the ball machine for elevation and stabilization purposes |
| Fusion 360 Model | 3D Design | Complete model of project |
| Ataraxy | Sticker (2D design) | “State of serene calmness” sticker |
| Graphical user Interface | Embedded Microcontroller Interface | Provides an alternate way from my computer to control the spin direction and speed of the tennis balls |
What materials and components will be used? (Cost + sources)¶
The below google sheet lists the costs, sources, and materials of everything that I will order.
Note that I will not be casting and molding the serve wheels of the tennis machine as there are insufficient material at my school. Additionally, it is difficult to create a precise resin cast. The tensile strength of epoxy is approximately 5 to 97 MPa, while that of mild steel is 200 to 2100 MPa. Also, the wheels will be spinning at around 1200 rpm, so they will be subjected to large centrifugal forces. Therefore, steel is better than epoxy for this purpose.
According to this calculator, with mass of wheel assumed to be 2 pounds, radius = 10cm, and rpm ≈ 1200, the centrifugal force will be around 334.2lbf, or around 1500 Newtons.
What questions need to be answered?¶
- How would I make the whole structure Stable enough so that the wheels don’t accidentally fly out?
- How to power a motor that runs on 10-15 amps?
- How will the stand be placed?
How will it be evaluated?¶
- How accurate do the balls land in regards to the tennis court?
- Will they land on the other side at all?
- How effective is the different spins on the balls?
- What about the speed?