Tic tac toe (or “zero and fork”) is a very simple game that can be implemented in any computer system: in fact, it is often used in programming courses for beginners. A more challenging project, which can be said to be more interesting and useful, is to manufacture some kind of hardware that can be used in real life. [mircemk] built a simple and elegant machine that can play tic tac toe against human players in a way that looks very similar to human confrontation: through painting.
The design and programming of the robot was developed by playrobotics, which named the project TICO. Mechanical parts can be used as STL files and can be printed by any 3D printer. A comprehensive manual explains how to assemble and program the whole process. Because it is open source, anyone can build it from scratch and modify it according to their preferences. The picture shows the original design of playrobotics, while the video (embedded after rest) shows the version of [mircemk], which includes a wooden frame to make it more existential.
A fully assembled TICO robot electronics is an Arduino with an OLED screen and buzzer, plus three servos to operate mechanical components. Without a 3D printer, [mircemk] cuts out plastic parts from a 3mm thick PVC board, which seems to work surprisingly well. The game board consists of a small whiteboard on which robots and humans can draw O and X.
The mechanical structure of the robot looks a bit like a little man who draws a huge marker with both arms. At the beginning of the game, the robot uses a small eraser to remove the whiteboard, and then draws a standard 3 × 3 grid and start the first step. Then, humans draw their actions and use the remote control to tell the robot what they have done (there is no machine vision), and then the game continues until there is a winner or the game results in a draw.
Although it seems that the playback strategy of the program may need some fine-tuning, the mechanical part is well designed and the movement of the arm is fast and stable. We like the “cheers” to celebrate at the end of the game, and TICO will do so whether it wins or not.
The basic design of the robot is inspired by plotclock, which uses similar settings to draw time. We have seen other tic tac toe Robots before, as well as some smart video game implementations.