Autonomous Tennis Ball Collector: Final Design Review (FDR) - Cal Poly

Autonomous Tennis Ball Collector
Final Design Review (FDR)
By
Frances Belcher
fbelche[email protected]
Matthew Hoffman
[e-mail]
Robert Lutrell
relutt[email protected]
Alex Petrov
abpet[email protected]
Michael Yiu
[e-mail]
Sponsor
Dr. John Chen
Mechanical Engineering Department
California Polytechnic State University
San Luis Obispo
June 2021

Statement of Disclaimer
Since this project is a result of a class assignment, it has been graded and accepted as fulfillment
of the course requirements. Acceptance does not imply technical accuracy or reliability. Any use
of information in this report is done at the risk of the user. These risks may include catastrophic
failure of the device or infringement of patent or copyright laws. California Polytechnic State
University at San Luis Obispo and its staff cannot be held liable for any use or misuse of the
project.

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Abstract
Practicing tennis often involves hitting many tennis balls from one side of the court to the other
without an opponent to hit the balls back. In training sessions like these, the task of collecting the
balls is laborious when performed manually. The objective of this project is to develop a robotic
tennis ball collector that can automatically collect the balls from one side of the court so that the
player can rest rather than collect the balls manually. This document outlines the process of
designing such a robot. Included in this report is background research, prototype, and concept
modeling, along with a finalized design, and a complete timeline of our process. We will also detail
the manufacturing process and the design verification. In the conclusion we will provide you with
recommendations for future projects. Throughout our research, we discovered many similar
products, but none met all of the customer’s requirements, thus opening a window for our product.
After copious design consideration, we selected the strongest idea that satisfied our customers’
needs and are moving forward with structural modeling and preliminary analysis on it.
After the structural prototype revealed issues in the design we went back to work and finalized
a design that we felt confident with and still satisfied all the requirements. As seen in this report
the final design utilizes structural framing materials to build the robot and allows for ease of
attachment for all the electrical components. The final step in the design process was to test the
verification prototype to ensure that it met all our specifications. Unfortunately, our design did not
pass as many of the tests as we would have liked, and this is detailed in that section. While at the
conclusion of this project, we did not complete as much as we hoped, there is a good foundation
in place for the project to continue as our sponsor so desires.

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Table of Contents
Abstract ............................................................................................................................................ i
1.0 Introduction ............................................................................................................................... 1
2.0 Background ............................................................................................................................... 1
2.1 Summary of customer observation ....................................................................................... 1
2.2 Discussion of existing designs .............................................................................................. 2
2.3 Table of patent search results ................................................................................................ 5
2.4 Summary of relevant literature ............................................................................................. 6
2.5 List of applicable industry codes, standards, and regulations ............................................... 7
3.0 Objectives ................................................................................................................................. 8
3.1 Problem statement ................................................................................................................. 8
3.2 Boundary diagram ................................................................................................................. 8
3.3 Summary of customer wants and needs ................................................................................ 9
3.4 QFD Process Description ...................................................................................................... 9
3.5 Engineering specification table ............................................................................................. 9
3.6 How to measure each specification..................................................................................... 11
3.7 High risk specifications....................................................................................................... 11
4.0 Concept Design ....................................................................................................................... 12
4.1 Concept design process overview ....................................................................................... 12
4.2 Concept sketches ................................................................................................................. 13
4.3 Concept design decision process ........................................................................................ 16
4.4 Description of selected design ............................................................................................ 17
4.6 Discussion of risks, challenges, and unknowns .................................................................. 21
5.0 Final Design ............................................................................................................................ 22
5.1 Description of final structural design .................................................................................. 22
5.2 Functionality of design ....................................................................................................... 25
5.3 Electrical and software final design .................................................................................... 26
5.4 Design justification ............................................................................................................. 28
5.5 Discussion of Safety, Maintenance and Repair considerations .......................................... 29
5.6 Summary cost analysis ........................................................................................................ 31
5.7 Structural prototype analysis............................................................................................... 32
6.0 Manufacturing ......................................................................................................................... 34
6.1 Part Procurement & Final Budget Status ............................................................................ 35
6.2 Manufacturing Processes .................................................................................................... 35

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6.2.1 Electrical Housing ........................................................................................................ 35
6.2.2 PVC Arms .................................................................................................................... 37
6.2.3 Rotating Cylinders ....................................................................................................... 38
6.2.4 Frame ........................................................................................................................... 38
6.2.5 Panels ........................................................................................................................... 39
6.3 Assembly............................................................................................................................. 40
6.3.1 Computer Vision and Motor Control ........................................................................... 40
6.3.2 Omni Wheels ............................................................................................................... 41
6.3.3 Rubber Wheels ............................................................................................................. 42
6.3.4 PVC Arms .................................................................................................................... 43
6.3.5 Chassis ......................................................................................................................... 43
6.3.6 Ball Collection ............................................................................................................. 43
6.4 Outsourcing ......................................................................................................................... 43
6.5 Major Build Operations ...................................................................................................... 43
6.6 Challenges & Lessons Learned ........................................................................................... 45
6.6 Recommendations for Future Production ........................................................................... 46
7.0 Design Verification Plan ......................................................................................................... 46
7.1 Specification Discussions ................................................................................................... 46
7.2 Description of Completed Tests and Results ...................................................................... 48
7.3 Description of Uncompleted Tests and Results .................................................................. 52
8.0 Project Management ............................................................................................................... 53
8.1 The Design Process ............................................................................................................. 53
8.2 Gantt chart ........................................................................................................................... 55
9.0 Conclusion & Recommendations ........................................................................................... 55
References ..................................................................................................................................... 58