ROBOTIC HANDWRITING?

[jeschwartz]

Hi All

I am looking to build a robot that can essentially mimic the motion of someone writing their name in a fogged piece of glass.  In short - I will have a machine set up to continuously fog a piece of glass and am looking to create a robot that can write two words on the glass. 

It should be as simple as possible yet reliable. IDEAS?  I appreciate your advice.

Thanks in advance!

Joshua!

[Soeren]

Hi,

I am looking to build a robot that can essentially mimic the motion of someone writing their name in a fogged piece of glass.  In short - I will have a machine set up to continuously fog a piece of glass and am looking to create a robot that can write two words on the glass. 

It should be as simple as possible yet reliable.

I don't think you realize what goes into building something like that and it certainly isn't a beginners project.
If you settle for something like simple unconnected letters with only squarish capital letters, you may have a chance.

You need to make the mechanical movements to better than 1mm resolution (for making eg, the diagonal line in the letter "N"" be a "straight" line rather than a staircase) and you need to build some programming skills, especially if you want the words to change every now and then.

If what you're after is to get the text on the glass continually, more than how, forming the letters in heater wire and applying power is much easier.

[jkerns]

Here is how it was done in 1810...

http://www.societyofrobots.com/robotforum/index.php?topic=15348.0

 

[Soeren]

Hi,

Here is how it was done in 1810...

By a mechanical wiz, not a beginner - now show us how you'd do it with a few motors and a controller

And I don't think that you'd put that old mechanical doll in the "simple" category?

[Pogertt]

Have you considered mimicking a 16 segment display?

A table of commands for each letter similar to the matrix to light led's.

[jkerns]

Hi,

Here is how it was done in 1810...

By a mechanical wiz, not a beginner - now show us how you'd do it with a few motors and a controller

And I don't think that you'd put that old mechanical doll in the "simple" category?

Simple it was not. Just imagine what it took to program it by cutting brass cams for each degree of freedom... Amazing is what I would call it.

Now, back to the original problem - is this robot supposed to write random phrases or just a couple pre-programed things?

One of the tough parts would be the math - first, mathematically describing the path for the tip of the arm and then sorting out all of the joint angles as a function of time to get it to trace the desired path.

One way around the math would be to build the arm with position sensors and then just move the arm by hand along the desired paths and record the angles. Then, the recorded values could be used as the target positions for your arm controller (a simple PI controller is likely to be adequate if you didn't try to move the arm too fast).  Create tables of time / position pairs to describe the paths for the arm.

If the arm was built with servos - that makes it more difficult to record the "training" movements because all the feedback is inside the servo's themselves. So, you would have to open up the servos and run wires back from the potentiometers to your micro-controller to record the servo positions as you train it. (And translate from the voltage from the pot to the pulsewidth sent to the servo to get that position - another training exercise where you command various pulsewidths and record the potentiometer output.)

Getting a robot to generate nice cursive writing was a challenge in 1810, and can be a challenge today!

[newInRobotics]

Build robotic arm and use inverse kinematics for path following.