We were on a robotics team together all throughout high school and wanted to get together and work on a robotics project again.

What it does

It plays tic tac toe, using a robot arm with 3 degrees of freedom to draw on a whiteboard and computer vision to see where its opponent placed their moves.

How we built it

The entire body of the robot arm is 3D printed, with some hobbyist servos to control the three axes. All of the computations for the robot are performed on a Raspberry Pi Zero which controls the servos via an I2C PWM board.

Challenges we ran into

The biggest challenge on the mechanical side was creating a robot arm that could maintain high precision and rigidity while still having low enough friction to move freely. The biggest challenges on the software side were implementing the inverse kinematics to drive the servos to the correct angles, as well as getting all three of the main components of the software (the inverse kinematics, computer vision and the tic tac toe AI) to work in unison.

Accomplishments that we're proud of

We are very proud of the fact that we were able to achieve all of our goals for the robot and that the systems all meshed together flawlessly in the end.

What we learned

By pushing servos to their limits we learned their shortcomings in an application that requires high precision such as the robotic arm in C-3XO. We also learned a lot about the operating principles of inverse kinematics and the different techniques that exist to solve the problem.

What's next for C-3XO

Because of C-3XO's versatile robotic arm, we can make it perform other actions. For example, we would like to be able to import image files and have it draw them on the whiteboard.

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