Museum of the Hand

Forty-five states in the U.S. have chosen to adopt the Common Core State Standards in order to give the nation a shared curriculum. The Common Core State Standards does not require children to learn how to write in cursive. The Common Core Standard for writing (W.4.6) states that by the end of fourth grade, students should demonstrate sufficient command of keyboarding skills to type a minimum of one page in a single sitting.

We made this interactive installation at the Delaware Center for Contemporary Arts to illuminate the beauty and importance of cursive handwriting.

The Cursive Machine portion of this installation was part of the Void Loop exhibition at Press Street’s Antenna Gallery in New Orleans, and included in a news report on WGNO (ABC) TV.

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The primary feature of the installation is the Cursive Machine, created in collaboration with my father, Robert H. Pigford, Mechanical Engineer (retired) and DIY programmer.The machine translates user input (10 alphabetic characters via a computer keyboard) into calligraphic cursive ‘printing’ via a wide-nib permanent marker.

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The viewer types up to 10 letters and/or spaces on a keyboard, hits the ENTER key.Then the Cursive Machine writes those letters on the paper in lowercase, cursive style, using its ink pen. The Cursive Machine moves the pen left or right and moves the paper up or down as needed to create the letter.When all the entered letters have been written, the Cursive Machine returns to the left side of the paper and awaits the next viewer’s letter selections for the next writing.

Cursive Machine “Self-titled” from Ashley John Pigford on Vimeo.

Cursive Machine “Documentation” from Ashley John Pigford on Vimeo.

The machine is wall mounted and consists of microcontrollers, software, stepper motors, stepper motor drivers, power supplies, hard rubber rollers, bearing blocks, an 18” wide roll of paper, and an ink pen for writing the cursive letters on the paper.A screen and keyboard are provided for the viewer to use as he or she interacts with the machine

cm-dramashot Image of Cursive Machine showing the keyboard and LCD screen.
cm-cu-electronics The machine is controlled by three Arduino microcontroller modules and four stepper motors with their associated stepper motor driver boards:1. Keyboard_SD_LCD Arduino (the one on the top, left of the machine)2.Tension Control Arduino (the one in the top, middle of the machine)3. GRBL Stepper Motor Arduino (the one on the top, right of the machine)

Pen and paper movements are directed via G-code commands which are text commands dictating exact position targets for movements in 3 dimensions.G-codes were originally created by the GE Fanuc Company to control the automated milling and turning machines they produced for sale to many industries.G-codes are in wide use today in almost all automated, computer numerical control (CNC) operations used to make things.G-codes are also used to direct 3D printing machines and other machines where precision movement in 3 or more dimensions is needed.

When the viewer has typed his or her desired letters or spaces via the keyboard,then hits ENTER, the Cursive Machine processes each letter separately from left to right as you would if you were hand writing these letters in cursive.For each letter or space, a G-code file exists on a microSD memory card mounted on the Keyboard_SD_LCD Arduino microcontroller.When a letter is to be written, the Keyboard_SD_LCD Arduino microcontroller finds the appropriate file on the SD card and sends that file’s text G-code commands to the GRBL Stepper Motor Control Arduino microcontroller where open source software called GRBL is running.

cn-cu-carraige Detail of the carriage that moves along the Y-Axis and raises/lowers the pen to the paper.

GRBL software running in the GRBL Stepper Motor Arduino microcontroller takes the text G-codes commands and computes values in terms of number-of-rotational steps and direction that the respective stepper motors should make to move to the next target point.GRBL then sends those values to the appropriate X, Y, or Z stepper controller boards.Those stepper motor driver boards, in turn, operate the three respective stepper motors, one for each direction:The three directions are:

·Xwhere the pen moves left and right,

·Ywhere the paper moves up or down, and

·Zwhere the pen moves down to the paper or up to a home position.

Stepper motors are special DC motors with 200 or more “steps” per one revolution of the shaft.The ability of a stepper motor shaft to turn in such small increments gives the machine its precision.

cn-cu-yaxismotor Detail of the X and Y-Axis stepper motors.

Mid-line and baseline

Note that some letters end at the mid-height position, and some end at the baseline height.A letter following a letter that ended on the mid-line must therefore start on the mid-line.There are 54 G-code files, 2 for each letter (mid-line start, baseline start), and two for spaces.

Before the G-code files could be made, letters were drawn and saved as .eps files using Adobe Illustrator software.Then each .eps file was subsequently processed with commercial software called Cut2D to create all the different G-code files.

Paper Tension control

Note that there is another Arduino microcontroller for Paper Tension Control.The weight of an unpowered roller is used to keep the paper taunt over a back-bar so that the pen will not snag the paper.The paper tension Arduino runs a program to maintain constant tension on the paper as it moves up and down (due to Y stepper motor action).To do this, an Infra Red proximity sensor is mounted below the un-driven weight roller.The IR sensor sends a position signal to the Tension Control Arduino microcontroller running PID (proportional, integral, derivative) software which creates an output signal. That signal is send to the Pololu stepper motor driver board which then directs the driven Tension Control roller to move in one direction (pull out more paper) or the opposite direction (send paper back in).The combination of these actions maintains the desired mid-travel position of the un-driven weight roller thereby maintaining uniform tension on the paper under the pen.

The skateboard wheels are positioned to hold the paper against their respective hard rubber rollers to prevent the paper from sliding on the driven rollers.

E-stop

An emergency stop circuit with red warning light is provided in case the pen carrying carriage moves to the left or right limit of its possible travel.E-stop kills power to the machine so that the stepper motor will not burn itself up.Resetting the machine requires the main power switch to be turned off, the carriage pushed toward the center of the traversing mechanism, and the main power switch turned back on again.

References

GRBL:
http://dank.bengler.no/-/page/show/5470_grbl
Stepper Motors and Stepper Motor Driver boards:
www.sparkfun.com/
www.pololu.com/
Arduino microcontrollers:
www.arduino.cc/
Cut2D:
www.vectric.com/

 

Tutorial Videos
The following videos are provided for gallery assistants to maintain operation of the piece.
The first thing to do if you experience any problems with the piece is to turn in OFF.

1. Turning the machine OFF
2. Turning the machine ON
3. What to do if the Red Light is on and the machine will not work
4. What to do if the pen dries out
5. Replacing the pen (only do this after trying number 4)
6. Re-aligning the paper in the machine
7. What to do if the machine runs out of paper: Step 1, Step 2, Step 3, Step 4