This week I finished the new arm drawings, and Mr. Bahn used the XCarve at his house to carve them. I also began testing a marker lifting mechanism based on magnetism. The marker will be mounted on a small piece of wood at the end of the arm. It will normally rest on the paper due to gravity, and to lift it, a current will pass through a coil of wire. This will create a magnetic field and interact with a magnet on the small piece of wood, tilting it up and lifting the marker off the paper. A rough sketch of the design can be seen below.
During the first few days of the week, I continued my work with the arm, and now it is able to use parametric equations to draw shapes. The prototype arm can now draw both X’s and O’s at a given location and size. The video below shows the arm drawing an O on the board, and many previous test O’s can be seen as well.
This week I began working with the prototype tic tac toe arm. It is controlled using a motor driver, a Raspberry Pi, and the GPIO software library. At this point it is difficult to use the hardware and software together. The first step is to create a parametric equation of the shape the arm should draw. Next, coordinates are converted into angles that the arm must create. Finally, these angles are converted into “steps” for the motors. This process is complicated, and while the arm can simply turn on and off for a set period of time, specific equations are not yet working.