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The Scribbler Bot

The scribbler bot is essentially a drawing machine that converts digital information into a physical drawing. The bot is made up of a software component and a hardware component. The software component analyzes a picture taken by a web camera (or just about any other image source), creates a unique line drawing from that analysis, and exports a point list that corresponds to the points that make up the lines. The point list is then sent as a series of discreet motor commands to the hardware component: a homemade orthogonal plotter. The plotter executes the motor commands to create a line drawing using a pen, pencil, or whatever medium you can attach to it with a zip-tie.

The scribbler bot was born out of an online drawing toy called the scribbler http://www.zefrank.com/scribbler . The scribbler creates complex and evolving line drawings out of simple ones, and is an attempt to stimulate and reward people that are not good at manipulating traditional drawing tools. The drawings are a collaboration between the visitor, who supplies the initial input, and the software which uses the input to guide its own original drawing. Zefrank http://www.zefrank.com and I have collaborated on a series of projects that create and display line drawings based on these algorithms. We became interested in ways that simple rules could generate complex line drawings that blurred the line between representation and abstraction. We wanted to create images that weren't just copies of the original, but instead embraced mistakes and wild unexpected variation. The scribbler bot was our first attempt to actually create physical pen and paper drawings that could be taken away by the participant. Our goal was to make a machine that could capture and draw people's faces quickly, while still maintaining a sense of originality, fun and surprise in the actual drawing. We embraced the idea of analogue distortions, such as motor vibration and broken pencil lead, elements that could feed back into the drawings themselves.

The Plotter
The first step in building the scribbler bot was finding a way to control and move the stylus along two axes. After doing some searching online I found several stepper motor control boards, some of which were controlled by either the serial port or parallel port of the computer. I decided on the A200-SMC, from http://steppercontrol.com , which is able to control 2 unipolar stepper motors through the parallel port of the computer. By embedding an ActiveX parallel port I/O control in Macromedia's Director I could send binary data to the parallel port and control the motors through the A200-SMC. Director was used to control the bot because I had used it in the development of the scribbler and it just made it easier to get everything to work together. To control stepper motors through the A200-SMC you could use any language that can send binary data to the port.

The stylus must be able to move in two directions, x and y. To accomplish this, the scribbler bot consists of two main parts, a main track system and a carriage system. The carriage moves along the main tracks for the x axis while the drawing instrument moves back and fourth along the carriage for the y axis. All of this is mounted to a piece of wood for the base. To support the main tracks angled aluminum was used, I measured in about three inches from either side of the base board and mounted each piece. For the tracks that the carriage moves along I used half inch electrical conduit and drilled holes on both sides of the angled aluminum bars so I could slide the tracks through.

To create the carriage a single piece of one inch square aluminum tubing was cut to a length just longer than the two electrical conduit tracks. Mounting linear bearings to the square-shaped box tubing was a bit of a challenge. One inch on three sides of the square-shaped tube had to be cut off, leaving an extra inch on the fourth side at the top. The bearing was put in the cut-out section and attached with JB Weld. The bearings on either side had to be parallel so they would not bind when sliding on the tracks.

Once all the bearings were attached I began mounting the motor and the y axis track. A piece of aluminum rod a quarter inch thick and another linear bearing with an inside diameter to match were used for the y axis. Two brackets were made to hold the rod to the square tubing. To get the bearing to move back and forth, one of the motors was mounted to the side of the carriage and a pulley on the other. A Quarter inch timing belt was used to transfer the motion from the motor to the bearing. The belt was looped around the pulley and around a matching sprocket that was fitted to the motor shaft.

To get the carriage to move along the main tracks I used an axle system to transfer motion from one side to the other. On one side of the base the other motor and another pulley were mounted. The brackets for these were made from shelving brackets and secured with some random bolts. On the opposite side, I attached two bearings from an old skateboard in custom brackets, and an aluminum rod as an axle. Sprockets were attached to the ends of the axle and some of the timing belt was looped from the motor to the axle, then from the opposite side to the pulley.

The first public installation of the robot was at TED 2005. Attendees could get their pictures taken by a webcam and could then keep the picture that the robot drew.

Live Video Scribbler
The scribbler software was used in slightly different method at the NeoCon convention at the Merch Mart in Chicago 2004. The installation was set up as live video version. There were cameras set in the ceiling that captured the images of people interacting with tablet of paper and pens. The images were captured 15 times a second then sent to a computer for scribbling. As the images were scribbled they were sent back out to projectors mounted in the ceiling and displayed on ceramic bowls at either end of the table. This installation was created as a collaboration between Ze Frank and Douglas McDonald for Core 77 and Herman Miller.

More Information
More information on the scribbler can be found at:
http://www.zefrank.com/scribbler/gallery/index_ran.html
http://www.tek-tonic.com/scribpage.php