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DrawBOT is a pattern drawing robot built on an Arduino microcontroller that draws a variety of patterns. It is built on a rectangular chassis with two rear wheels driven by controllable motors. Patterns are drawn by three markers at the front. The middle marker is the third wheel for both balance and drawing. The other two markers can be lifted of the drawing canvas to create variety in the pattern. The type of pattern depends on the speed of each wheel and the marker controllers.

The first major step was to power and control the wheel motors such that each motor could rotate independently. To do this, the two motors were connected to the battery and the microcontroller through a quadruple half-h L293NE as shown below. In order to modulate the power input for the motors, the motor control pins were connected to Arduino Uno’s pwm pins 5, 6 and 9, 10.

The second major step was to vary the pattern colors by turning the markers on or off using the microcontroller. The middle marker which is also the front wheel, is always ‘on’. Two markers on either side can be turned ‘on’ or ‘off’ by using solenoids. The solenoids lift the markers off the surface when its input is high and release the markers back onto the surface when its input is low. The solenoids were inverted to lift from the base which provides a more convenient flat surface compared to the top. When power is high, the solenoid pins lift the small plates to which the respective markers are attached, thereby lifting the markers of the canvas. In this way, the patterns are composed of 3 different colors, the middle always being on, while the two side markers are on and off depending on the setting.

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