member: Kosuke, Yuji, Joshua, Sho

Embeded encoder switching system on 2-axis MTM stage

IDEA

Since 2-axis MTM system only has a function of X-Y positioning, the third channel is required if pen drawing or any other application.

Schematic MTM X-Y STAGE with encoder-switching as third channel

Our basic idea is adding third channel without any new gestalt-node but only adding encoding switches. Two rotary encoding-disk are added to the stepping motor, and the complex photointerrupters are combinated with a RS flipflop. This system provide special X-Y addresses to turn ON/OFF the third channel. Since most of the other position are just holds the condition. By modifying the python program, It can behaive as 3 channel machine!

Path of drawing characters with our scheme.

The two photo interruptors (PI) are mounted with phase shift of the encoding disk, for example, PI-A is 0deg, 18deg, 36deg,.... and PI-B is 9deg, 17deg, 45deg,.... The RS flipflop controls third channel. It is set by "(A and D) or (B and C)", and reset by "(A and C) or (B and D). To draw line, MTMs moves to nearest "ON" position for turning-on first, and move to the end point without passing over the "OFF" position. To move without drawing, MTMs moves to nearest "OFF" position for turning-off first, and move to the end position without passing over the "ON" position.

Electronic design and fabrication (Sho, Yuji)

The encodiner switch's RS-Flipflop and fabnet is designed as follows. Two 7400 privides whole cirwuit. We insert coupling capacitors just before the RS-flipclop for inversion and defferential pulse.

The circuite design of the signal process.

The test circuit was fabricated by the breadboard. From the testresult, the phototransistor load registers of 4.7kOhm were adopted.

Top view of encoder circuit on bread board.

Encoder Unit fabrication (Sho, Yuji)

The photointerrupter's adjustable mounters and encoderdisk was designed by Stechup and 3D printer (Agilista3200).

Design of the encoder unit (Sketchup).

X-Y Stage fabrication (Joshua)

The X-Y stage was made of wood board. The encoder spaces were kept just in front of motors.

Design of the encoder unit (Sketchup).

Python Programing (Kosuke)

We programming the Python to drawing as following:

  1. Move to the nearest turn-off position
  2. Move to the beginning position without passing turn-on points
  3. Move t0 the nearest turn-on position
  4. Move to the ending position without passing turn-off points.

Final Assembling and Demonstration (Sho, Kosuke)

3-channel machine without 3rd channel machine. We got 2 MTM for making 2-axis machine. Even though we add pencil or something to it, all we can output is something inicursal like this. So we made this machine. This is the movie of the machine. Movie For example, let’s draw the figure ”ニ”; Japanese kanji. At first I input the figure in the application we made. After that, the machine moves and the LED become bright on the correct occasion. Here is the picture of successful experiment. But too bad the path is too narrow and we can’t figure it out. There are two encoder in it, and it can detect where it is. Also we prepared a program for drawing whatever we want. Our basic idea is adding third channel without any new gestalt-node but only adding encoding switches. Two rotary encoding-disk are added to the stepping motor, and the complex photointerrupters are combinated with a RS flipflop. This system provide special X-Y addresses to turn ON/OFF the third channel. By modifying the python program, It can behave as 3-channel machine ! 1.LED ON/OFF MAP At first, we decided the relationship between the place of LED and whether it becomes bright or not. 2.Electrical circuit In order to realize it, we made the schematic like this. 3.drawing program Using "ON/OFF area" and "keep condition area", we can make different figures. For example, let's draw this figure using our machine. In order to leave origin to starting point, you need to make it move like this. And in order to leave the end of the figure to starting point of another figure, you need to make it move like this. In future, we are planning PEN-UP/DOWN with this system, but we have finished it not, yet. To confirm the scheme, we use RED-LED and try to write "=" character. The movie is as follows: Movie