Chess-inator
The Problem
For this school project, we were tasked with creating a system that used 2.5 degrees of freedom to accomplish an outcome of our choosing. My team decided to create a robot capable of manipulating chess pieces in 3D space. We named our robot the Chess-inator in an homage to Phineas and Ferb villain Dr Heinz Doofenshmirtz (pictured right).
The Solution
Design Challenges
This project had 3 primary components: The structure and layout, the electronics and integration, and the end effector including the Z axis.
The structure was fairly straightforward - we decided on aluminum extrusion construction and stepper motors with a belt to drive motion. The board itself was cut from a sheet of acrylic and engraved with a scaled image of a chessboard. Acrylic was chosen for its ease of workability and final surface quality.
The electronics were complicated because of our chosen manipulation method and control board. We elected to use an electromagnet to capture the piece and a servo driven Z axis to raise and lower the pieces. While the servo could be controlled directly by the MKS 3D printer board, there was no output for the electromagnet. We had originally planned to use the fan output as a switching 12V source, but were unable to validate that method. In the end I found that a motor output could be manipulated into outputting 12V across 2 of its 4 pins with a specific GCODE command. Using parts outside of their intended use case was the breakthrough needed to make this project possible.
The end effector was engineered with packaging as a priority. Lightweight was a necessity so that the system could make moves as fast as possible. It would have been easier and more precise to use a much larger stepper motor, but that would have raised the weight and size of the end effector unacceptably. Instead, a servo motor was chosen. The servo motor had adequate accuracy and power to move the weight of the electromagnet and a piece without being over-specced (and overweight) for the job.
Outcome
In the end, our team created a robotic system capable of consistently moving chess pieces around the chess board. The system was reliable enough to play through an entire game without misplacing pieces or losing its spatial calibration.