THE PEN GRABBING SYSTEM (THE ARTIST)

PEN GRABBING SYSTEM (THE ARTIST)

Play "La Vie En Rose" by "Édith Piaf" to see this post.

This mechanism took 14 tries.

Yes 14 different prototypes were developed, printed out in plastic and tested. The last version (Prototype 8.5) as seen in the pictures nailed it.

So what is this?

This contraption is your wrist as a matter of fact. How come?

Well because I say so. End of story. I made it, apparently that means I get to say whatever I want.

So there's a lot of things going on. First, This mechanism is an exact replication of a human wrist. It enables me to mimic the human wrist movements to write on a paper with asymmetrical paint brushes. See the pictures to see the brush/pen in question.

Technical Stuff...

oh man this is going to be long...

So,

This mechanism has mainly three different kinds of movements. The two general rotations of the wrists (flexion and extension) and (radial deviation and ulnar deviation) and a twisting of pen through fingers.

These two rotations are achieved by two servos which are placed against each other through a very "simple" mechanism (took 14 prototypes to get it, just saying it's simple anyways).

The mechanism is a locked gear with one of the servos while the other servo is connected directly to the main body which is rotated.

On top of all this. The very important movement - twisting of the pen by human fingers is also implemented by servo located against the previous servo as mentioned.

Again, On top of all of this, this mechanism is also directly responsible to grab a pen, lock it in place and then use it with all of the aforementioned movements.

How does it grab the pen? The servo which is located near the end rotates a gear attached to a vice like mechanism with three teeth which is attached with a helical gear system to move all the teeth linearly.

All of this achieves a movement equivalent to the human wrist.

The Vice Mechanism

The vice mechanism is the most important mechanism in all of this. The whole structure was made around it, This mechanism has only three teeth which failed repeatedly due to the high friction in the printed parts due to imperfect surface finish in the lower surfaces as they were freely hanging while getting printed.

After a few careful sanding and greasing attempts. The mechanism worked enabling smooth movements with the servo capable of turning the mechanism tightly around the pen. Silicon grease was used in all the gears and moving parts.

The vice mechanism is shown in the 3D model Viewer below and a lot of pictures at the end.

The 3D Interactive System Assembly

There's also a bunch of mathematics involved in making the teeths self locking and not slidable with force applied in the reverse direction. Too lazy to explain that. Look up ball screw mechanism and gear mechanisms in general to understand that. Essentially it's a cam system.

The Electronics

Nothing much in this section. Just a few servos mainly futabas connected to a microcontroller - ESP32. That's all. ahaha.

The Software

i t ' s a s e c r e t

The Assembly

I love bolts so much, I used so many of them. This contraption has way too many bolts.

To assemble them, you would need 3D printed parts, assorted M3 and M2 bolts, nuts and washers. Servos mainly any 3 Futaba equivalent of TowerPro 995 and 1 MG90s.

The whole thing is then attached to a robot arm.

(This is not available to the public, Its just me flauting my B.S.)

[ The "North Carolina Girl" took my 2 dollars at the bar. Man, I can't pay for Ramen now. ]

- Made in Studio de Roro, France and Office of Faraday, R.I, United Kingdom by RolandThsive

Have a nice day,

Rohit