Process overview:

It is a simple task to control small electrical signals which are carried by the wires attached to the printer port of IBM-compatible computers. As with all computer information, these digital signals ("bits") are either "on" or "off." Very basic motion control can be accomplished by simply using these signals to turn on/off more powerful devices (eg. the electric valves in "Pipedream"). More complex motion can be achieved by coupling these signals to the turning of electric motors. This, in fact, is the foundation of "CNC" -- computer numeric control, where the travel of a tool is governed by motors which act in concert to achieve a programmed path.

Perhaps the simplest illustration of this strategy is an Etchasketch, whose knobs are connected to motors. Instead of the left hand controlling the horizontal motion, and the right the vertical-- a computer running custom software sends appropriate signals to the motor circuitry so that a predetermined path is followed.

With the goal of making these simple ideas accessible, I have created the course entitled, "From Bits, To Bytes... To Bots."

Let's move on to a more sophisticated example-- a pen plotter. Again, the tool (pen) motion is broken up into two axes-- X and Y, and controlled via motors. In this case, the option of tool active or inactive (pen down vs. up) has been added. Tool path information is stored as a list of consecutive X,Y coordinates (plus pen dn/up info for the plotter). Such a format is the structure of all "plot-files," and is readily output by drawing programs such as CorelDraw, Adobe Illustrator, and all CAD programs.

These are examples of linear motion control in 2 dimensions-- but the process can be generalized to other coordinate systems (cylindrical, spherical, etc.), and to 3 or more axes.

Now... instead of a pen, why not an engraving bit, router, cutting torch, laser, ...?

 

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Deeper: electronics, mechanics, and programming.