Let's Make Robots!

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Needs to be hard programming.
Chris the Carpenter's picture

I have seen similar bots go by and I often wondered how the X/Y worked. Oddly enough, it seems I have been doing this for a long time. --I have done a lot of occupancy grid kinda stuff, where I will have a sensor swept by a servo. The angle of the servo and the distance of the sensor had to be converted to an X/Y so I could find out where it landed on my grid.

Now it seems, you have a machine that does just the opposite. Once I dug in and started googling catesian and polar, I quickly found out how easy the math really is and that Arduino really has no problem doing it. Man, you really got some ideas going around in my head here....

Yeah, I think I may just have to build one of these guys. --Now, should it be a super-light-3d print-$5 stepper-unit  or should it be a NEMA23 200oz/in robot arm out of milled aluminum? Ah, decisions, decisions...

Oh, and your construction is to die for. Beautiful build. Great execution.

alegiaco's picture

Yes, the math is easy.

The problem of polar arms is the error is not costant in the workspace. For 1 step of the motor, the error is radius*angle_for_1_step, so if the arm is near the origin the error is small, if it is far the error is big.

You can use a light stepper, the weight is low, but the precision is important. I use motors with 400 step, 0.9°.


This looks good ! :-)


bdk6's picture

This is quite nice.  I will have to look at the link for details.  I am very interested in the algorithm.  Great work!  I think it is better art and more meaningful than a lot of the crap done by people.

alegiaco's picture

The robot draws better than me, it's sure!!!

mogul's picture

Fascinating, well done!

The data for the actual drawing, that is stored as an array in your arduino it self or in some sort of external memory?

alegiaco's picture

Hi the data are calculated in real time. They are not stored. The algorithms to draw the different building are stored in the Arduino RAM memory (2 kB). The robot can also write and the path to draw the characters is stored in the Arduino program memory (32 kB).

ossipee's picture


 have been enjoying the drawing bots lately, and you have a winner there.