Summer 2018 Robot Challenge
The first iteration of the Amherst College Design Challenge Team (also known as the Mammoth Makers) strived to design and build a robot capable of playing soccer. To achieve this objective, the Mammoth Makers asked:
- What does it mean for a robot to play soccer?
- Which skills and bodies of knowledge are needed to build a robot?
In the first phase of the project, the Mammoth Makers developed the technical skills necessary to generally build a robot. In the second phase of the project, the team replicated and built the design of the Wash U design team for the American Society of Mechanical Engineering (ASME) Student Design Competition in 2015. In the third phase of the project, we used the knowledge and experience gained in the prior stages to innovate the Wash U student design and finally begin the construction of our soccer-playing robot. Finally, we will prepare to share our creation with the world and reflect on the process of designing and building robots.
Inform Phase
In the first phase of the project, the Mammoth Makers created tutorials on relevant bodies of information which would become important in the later phases of the project covering the topics of:
- Electronics
- Motors & Gears
- Computer-aided Design
- Chassis Parts & Assembly
- RobotC
After the completion of the tutorials in week 1, each team member completed and assessed the tutorial during the second week.
Imitate Phase
In the second phase of the project, the Mammoth Makers sought to build a robot of their very own agreeing with the rules and guidelines of the 2015 ASME student design competition. The robot built in this phase was a culmination of pre-existing robot designs. Originally, we were going to build a robot imitating the design of the 2015 WashU student design team, but in our process of research and exploration, the team decided to replicate individual components of the robot. The robot was subdivided into three parts: the chassis, the launcher, and the controller.
Innovate Phase
In the third phase of the project, the team prototyped, designed, and built a robot of their own design. This robot also adheres to the ASME guidelines, although some rules for soccer playing were modified. The building of the robot was again divided into three subsections: the subsystem (launching & collecting components), the chassis, and the controller. Some launching and collecting mechanisms were prototyped before final designs were selected for placement on the robot itself. This robot is also wirelessly controlled, which is pretty cool!!!
Meet Eugene Crabs, the soccer-playing robot
Goals
Before the construction of the robot, the team highlighted the specific goals we wanted the robot to achieve:
- Move in all directions
- Be able to turn and rotate
- Collect a tennis ball from the ground
- Hold a tennis ball
- Aim & expel a tennis ball
Competition Rules
The rules for the original 2018 ASME challenge can be found here.
After some discussion, the design team decided on the following rules (adapted from the rules above):
- The arena will be 5m x 5m with two 50cm x 50cm goals on opposite sides. There will be a two 50cm x 50cm penalty boxes in front of each goal.
- The robot will be within 50cm x 50cm x 50cm and battery powered.
- The game works as such: Starting with four tennis balls in the arena, the (singular) robot attempts to score in either goal. The game is over when all balls have either been scored or hit out of bounds.
Subsystem
The subsystem of the Cheshire Cat has two components. The first component of the robot is designed to collect a tennis ball and the second component of the robot is designed to eject the ball.
Collection Component: Pinball Flipper Arms & Zip Tie Intake
The collection component of the subsystem consisted of a mechanism resembling pinball flipper arms and an intake system reminiscent of a vacuum which is constructed from zip ties. The combination of the two mechanisms serves to ensure the robot will consistently and quickly retrieve the ball. During the construction of our robot, we integrated a conveyor belt and latch system to hold the ball after the flippers and zip tie intake have done their job.
Ejection Component: Two-wheel Launcher
The ejection component of the subsystem is two-wheel launcher is exactly what it sounds like - two wheels powered by high-speed motors and separated by a distance wide enough to accommodate the presence of a tennis ball.
In our design process, the team wanted to build a robot which acts in a manner consistent with playing the true game of soccer as much as possible. Thus, we aimed to construct a mechanism which would collect the ball from the ground for collection component and another mechanism which would more readily shoot laterally rather than vertically. Furthermore, we wanted a subsystem which would collect and shoot the ball in a matter of 10-15 seconds. The ball is collected from the front of the robot and the expelled from the back of the robot.
Chassis
We used an H-shaped chassis for the Cheshire Cat. This shape left space for the intake and expulsion mechanism to be added in later. The chassis also included four turrets on each corner of the robot. The turrets were designed to support/contain the gear system associated with each wheel and wheel motor. At the top of the four turrets, we created a second level of the robot. This second level was used to hold the electronics and provided for easy access to most of the wiring. To make the H-shape more stable, on the second level of the robot we added support bars making a modified-H shaped, or box-shaped, upper level. The mecanum wheels provided omnidirectional movement allowing the robot to move in all directions, turn and rotate.
Controller
For this robot, we decided to use a Logitech Gamepad F310 as a controller. To program, we used a combination of the Arduino and Processing IDEs. The controller uses code from Arduino and Processing to communicate wirelessly with the robot using Xbees (hardware) and XCTU (software). The mapping from the controller to robot motors was as such:
Motors
We used three different types of motors: standard servo motors, continuous rotation servo motors, and brushless DC motors. Standard servo motors are high torque motors with a limited range of movement (100 degrees). These motors were used for the pinball arms and the two-wheel launcher’s latch mechanism. Continuous rotation servo motors are high torque, medium-low RPM motors. They were used for the zip-tie intake and conveyer belt. Brushless DC motors are the fastest of the three motors; they have such a high RPM that we used both hardware (gear system) and software (manipulating code) to lower the RPM. These ridiculously fast motors were used to power the mecanum wheels and the two-wheel launcher.
Acknowledgments
Thank you to Prof. Carter and Megan Lyster for their guidance throughout the summer. You helped us break down a massive project into tangible parts and build something we’re proud to share with the Amherst community.
Shout out Brian Crepeau for his invaluable help with all things electronic and for his general robotics enthusiasm. We have learned so much from you and plan to continue sporadically visiting you in your office.
Meet the Team
Abdoulaye Sanogo ‘19E
Abdoulaye is a Physics and Political Science Major who plans to pursue either mechanical or electrical engineering in the near future. He has served as the president of the hip-hop club on campus for most of his time at Amherst and enjoys basketball and stand-up comedy.
Allan Phillips ‘20
Allan is majoring in biology and possibly computer science, and he plans on pursuing a career in genetic research and/or engineering. He was an avid member of his high school robotics team, which has contributed to his interest in designing/building robots. He loves listening to and playing music with friends in his free time.
Donna Roscoe ‘21
Donna is fascinated by biology, psychology, and neuroscience, and hopes to become an engineer. This summer has ignited an interest in physics, which she will be pursuing this next semester. In her free time, Donna enjoys looking for fireflies, eating non-orange flavored fruit snacks, and baking pizza with IS ‘20.
Devin Epstein ‘21
Devin is a sophomore at Amherst, majoring in Physics. He hopes to extend this into a career in aerospace engineering or research. His other academic interests include music, German, and astronomy. In his spare time, he enjoys being outside, reading, and playing Frisbee.
Ellen Mutter ‘18
Ellen just graduated from Amherst, double majoring in Mathematics and Music. She has greatly enjoyed spending the summer learning about robots and is happy to have survived her few encounters with smoking and sparking batteries and motors. Next year she’ll be working in a less smokey environment (hopefully) as the Assistant Director of the Amherst College Choral Society and as a Graduate Assistant in the Music Department.
Ingrid Shu ‘20
Ingrid is a math major, a member of the swim team, and a big fan of making pizza with DMR ‘21. She has recently discovered a love for haikus, which is unfortunate for those who have to read them.