# Design of Automata

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Modern automata are crank driven mechancial sculptures that show some sort of object in motion. The design of these machines can be very complex, and requires a lot of experience. However, by the help of computer design software it is possible to make the process much easier. Over the course of several years, I have refined the design process so that models of automata can be made very fast.

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## Step 1: Software

The softwares used in the design process are:

• Solidworks
• SAM Mechanism Designer
• Ghost-it

I used Solidworks for this example, but any software that allows for drawing of shapes and adding constraints are fine.

SAM Mechanism Designer is used for initial prototyping, as it is very fast for these type of tasks. The software is not free, but a demo version is available at:

http://www.artas.nl/

Ghost-it is used for seemless transition between the other two programs. It can overlay one program window on top of an other, much like tracing paper or a lightbox. This eliminates the process of export and import and makes is possible to use the best features from both software packages. On top of that, it is free!

## Step 2: Reference Material

Every good automata begins with good reference material. The reference material should contain information about shape and motion. Good sources of reference material for automata are:

• Video
• Photography
• Animated .gifs
• Medical or technical drawings

In this example I will use an animated .gif of Pikachu as my reference material. I found it via Google Images by limiting the results to animated images. Animated .gifs are great because they contain only the most important positions in order to describe the motion.

## Step 3: Mechanization: the Basics

The 4-bar linkage forms the basis of planar linkage mechanisms. It will transform circular motion into oscillatory motion and is the simplest planar linkage you can make.

Degrees of Freedom (DOF)

Degrees of freedom is a term that tells in how many indepentent ways a mechanism can move, or the least number of coordinates needed to describe the system.

Automata usually have one degree of freedom. If the crank is turned, all the other parts will move in a prescribed fashion. It can be shown mathematically that in order to achieve this, the total number of links has to be an even number.

Including the ground link, it can be seen that the 4-bar linkage has one degree of freedom. Subsequently, if two more links are added to a 4-bar linkage, we get a 6-bar linkage which also has one DOF. This way, a more complex machine can be created; simply by adding more and more links.

## Step 4: SAM Mechanism Designer

SAM is good for initial design of mechanisms.

1. Draw links with the 'Create beam element' tool.
2. Fix joints with the 'Fix node in X- and/or Y-direction' tool.
3. Add motor by clicking on 'Angle Input Motion' and selecting the driving element.
4. Right click > 'Show path' to trace the position of a point.
5. Reposition joints to achieve the motion you want.

As you can see, it is a super-fast way to experiment with linkages. It is also possible to make many other types of joints, gears, belts, etc.

## Step 5: Start Simple!

Start simple! Here I started by making Pikachu's body rock back and forth with the help of a 4-bar linkage. Remember that the links can have any shape or form, it is the position of the joints that determine the behavior of the mechanism. You can make the links have different shapes by adding elements to it so that it forms a rigid triangle. For instance, I sketched out the position of the hip joint by adding two beam elements.

## Step 7: Front Leg

• I changed the shape of the main body to locate the shoulder joint.
• Then I drew the leg, represented by a triangle.

## Step 9: Rear Foot

Finally, I added the two last links which formed the rear foot.

## Step 10: Solidworks Layout

For creating a more detailed design, I will now switch to Solidworks. Solidworks has a feature called 'Layout' wich allows the user to create a layout of an assembly.

1. File > New > Assembly.
2. On the left hand side, click on 'Create Layout' in the yellow box.

## Step 11: Sketch

1. Trace the mechanism from SAM into Solidworks.
2. Click on each element and create a block.
3. Add contraints such as 'coincident' or 'anchor'.

Repeat the process for all of the links.

## Step 12: Taking Shape

Each block can be edited to that they look more like the real thing. Use the original reference and trace the shape of each part. Make sure to have the correct level of zoom while tracing.

## Step 13: Results

The design of the running Pikachu took less than 90 minutes, but it will of course depend on your experience and the complexity of the automata. Try it out yourself!

## Step 14: Appendix

3D files, along with templates for the pikachu automaton can be found here:

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## 14 Discussions

so i'm getting this whole design laser cut but what dimension should i cut it so that the nut and bold will fit perfectly in the provided holes?

Thanks!

I used a 3 mm drill bit to make the holes.
I don't know what would be the best dimension for laser cutting. Perhaps you could try different sizes and see which fits the best?

Wow the software is really cool, but 2k is a bit steep !!! Love the design, voted for
It, but can't afford the software. :(

3 replies

It will animate when the windmill icon is pressed. The reason I use SAM is that it is very fast to draw and see how the mechanisms work. A lot of other programs have the same features, e.g. Solidworks, but are often slow, or not very user-friendly when it comes to this specific task. Unfortunately you can not save your work in the demo version, but you can however export as .dxf.

As a student, I have always had access to a high-end CAD tool, but you can probably find free CAD tools that will do the same thing. You could always draw each individual part based on the design made in SAM. Then just refine the shapes and assemble the parts.

I made the animation by taking screenshots in Solidworks at fixed intervals and combining them into an animated .gif.

Such a nice Instructable ! I discovered something today.

Thanks a lot. And I loved the thief automata.

Thank you for the great post. automata in some ways is a main ancestor of robots. Yet it never loses its magic. I think a free software like PHUN-Algodoo is a great free automata practice & development software. BTW:which one you think is best to give you cutting blueprints or MTO

Very impressive. I'd love to see it completed and moving.

Great info, thank you!

I've always been fascinated by automata, and planned to get into it at some point. Creating the designs digitally makes a whole lot more sense than doings so through trial and error. Thank you again for sharing this!