We love drawing on walls. Our home turf, East Campus, is covered in murals from students of the past. We wanted a way to add computer-generated murals as well, but CNC plotting on the scale of a wall is impractical with a large device. To solve this, we developed a hybrid device that uses human positioning, machine vision, and CNC plotting to make a large image out of small plots.
What it does
First, hold NeuroDraw on the surface you would like to sketch on. Load an SVG image file, set a scale, and the device beings drawing the bottom corner of your mural. When completed, NeuroDraw prompts you for human intervention. Pick up the device, place it off to the side, and let it continue. An Nvidia Jetson snaps a webcam image of the part you already drew, identifies key features, and determines its new physical position. With a new origin, NeuroDraw continues by plotting the next section of the mural. By repeating this process, continuous murals of boundless size can be drawn.
How we built it
An X-Y translational stage uses stepper-motor-driven lead screws to precisely position the pen in 2D space. A manipulator uses a servo motor to raise and lower the pen on and off of the material. These axes are driven by two Arduinos, which are dedicated to controlling the plotter's position. The Jetson, hosting the Arduinos over USB, streams a buffer of generated lines to be plotted. The Jetson is the true brain of NeuroDraw, taking image requests wirelessly, generating the current list of vectors, and directing the user when movement is required.
Challenges we ran into
Mechanical challenges slowed our early development. The limited capabilities of the provided stepper controllers (no current limiting, overheating, etc.) made the X-Y stage unreliable. We were able to move past this by integrating new components.
Accomplishments that we're proud of
It plots beautifully! We were able to download vector graphics online and recreate them on our whiteboard. Our computer vision can capture images and determine relative position.
What we learned
1 - Everything takes longer than you think it does! 2 - Always have a plan B, C, D, and E. With tight time constraints, you always need to be ready to swap approaches.
What's next for NeuroDraw
Developing a smaller product that is easier to hold against a wall. This is the intended application, and would make use much more convenient. This result could also be a professional product.