I have been spending the last few months doing research into biologically inspired robotic structures. While my approach may seem formalistic in nature, these devices were simply a means for ultimately conducting social research. This desire stems from my experience building Simple Bots, and their subsequent display at multiple Maker Faires.

While displaying these robots, I observed that the thousands of people who interacted with them, projected their own social realities upon these devices which were little more than motors zip tied to plastic household utensils. The obvious shortcoming of the Simple Bots approach was that no matter what personalities people projected upon these creations, they ultimately implicitly understood that these creatures were robotic.

This led me to wonder what would happen if I built robots that were more intentionally organic-like and fluid in motion. Would people perceive them as being even more alive? Was there a threshold where people would stop perceiving them as robots and start perceiving them as living organisms? However, before I could answer these questions, I needed to figure out the mechanics that would allow these motions.

While I could have explored a number of different fabrication processes, I recently found myself with unlimited access to eight Objet Connex 500 3D printers. Aside from having an incredibly high print resolution, what makes these printers unique is their ability to print digital materials with a wide range of hardnesses and colors. These printers essentially allow the different materials to be mixed together to create a Pantone-like scale for material hardness. This was particularly compelling for this type of robotics because it would provide the ability to print highly accurate assemblies that simultaneously contained rigid and flexible materials. By printing materials with different hardness, flex, stretch, and torsion properties, I would be able to print life-like joints and musculature. With this in mind, I set out to make biologically inspired designs using 3D printing technologies.

All digital models were created using 123D Design on account of its ease of use, and ability to be downloaded and used for free. This is an intentional decision to make the project open, and modifiable. It is my hope that others will be able to download my files, iterate upon my solutions, and ultimately expand my research. All content contained herein is licensed with a Creative Commons 2.5 Share-Alike Non-Commercial Attribution license.

Step 1: A Note on Evolution

When I started to write this guide, my initial intent was to call it "How Not to Build a 3D Printed Robot." When explaining this desire to a colleague, I arrived at a new potential title which was "Failures of Robotic Evolution." However, comparing robotic design to evolution is problematic in a number of regards, and opens up a large can of worms. As Steven Vogul arguest in "Cats' Paws and Catapults," the design and evolutionary processes should not be conflated.

Most notably, Vogul points out:
  • "nature is not only glacial in speed, but lacking in versatility"
  • "most variations [mutations] are either neutral or detrimental"
  • "innovation comes hard, and once achieve it disseminates entirely within a lineage"
  • "diversity in nature represents superficial features of an exceedingly conservative and stereotyped character"
He then goes on to explain how for human innovation, design is a much better model because fundamental design change faces no evolutionary barriers. For instance, a design can be fundamentally changed without taking into consideration the need for each subsequent iteration to allow perfect functionality to perpetuate the continuity of its lineage. Nor do we have to account for growth or scaling of the object over its lifespan. Humans are only limited by the materials at hand, the existing knowledge base, and ingenuity. Humans are also free to borrow, adapt, and remix designs at will. Most challenges for human design innovation tend to be social and/or legal, not formalistic.

While it may be tempting to describe robotics in terms of evolution, I think it is better to view it as an iterative process. This process, while very similar to evolution, is noticeably different. As evolution repeatedly demonstrates, most change is detrimental, blind and slow. Iteration, on the other hand, is (ideally) beneficial, intentional, and fast. One rarely iterates if they don't think the subsequent version is going to be an improvement or will illuminate something that will help to move other iterations forward. Just as organic-like machines are similar to life, but not replicating it; so is the case that the process for making these machines should be evolution-like, but not a perfect repetition.
<p>Please update the videos they are all broken :(</p>
<p>I see. Very frustrating! I will see about finding the original video files soon. They are likely on a backup hard drive I don't have with me at the moment.</p>
I read through this instructable with interest - I've done a certain amount of R&amp;D on walking robots, although I tend to use servos instead of the more organic approach presented here. However, I disagree that walking robots like that have to look clunky and awkward. This video shows my quad walker Roz walking at a pretty good clip, and it looks very natural and organic to me, even though the legs and foot positions are all calculated using inverse kinematics.<br> <br> <div> <div> <a href="https://www.youtube.com/watch?v=6le3z78TK74" rel="nofollow">https://www.youtube.com/watch?v=6le3z78TK74</a></div> </div> <br> Roz has a bunch of 3D printed parts, BTW. They were all printed in ABS on a Dimension uPrint printer.
What a brave and great endeavor! From your conclusion I taste some frustration about the pile of hard work you had to do and getting little answers back about your social research. I say: Despair not and keep going. Knowing what does not lead to answers is valuable too :-) <br> <br>Thumbs up, it's a magnificent Instructable and you went through a great process. <br> <br>Y.
I am humbled to be able to learn from the detailed experience of this author.<br> <strong>Thank you Randofo,</strong> excellent documentation!
the final video her shows awesome promise, perhaps if you replaced som the parts with more robust plastics or other material, and turned the leg assembly so the wire being tensioned wasnt on the cardinal points, but slightly off you would generate more forward motion <br>
Hi Randy. <br> <br>I have some &quot;constructive&quot; criticism of your robot design. To have the robot stand still seems to require quite a bit of power. All eight joints need to be in tension. This seems some what wasteful to me. Would it be better to produce a joint that at rest is in a standing position. This would require less power and mean lower forces on the parts and materials. I realise this is built from an artists perspective, but it does require quite a lot of engineering. <br>I think the materials and method of production would stand up to use if the robot was designed to be more energy efficient. As human beings, our legs need very little power to stand still. At rest they support us. With the aid of gravity we find it easy to sit, and to work against gravity and stand we are returning to that state of rest. I know very little about kinematics but I would assume the tendons etc in our legs act as springs to help lift us from sitting to standing, so helping to overcome gravity with less power input. I think this sort of thought would produce a design that would be more tolerant of use. <br> <br>Just my thoughts. <br> <br>Good luck with your project and I would love to see more design iterations of this robot. <br> <br>Rob <br> <br>
Thank you for posting this! It was an interesting read and I was hoping you would have more success with your methodical approach! <br>In the 90's I built a number of prototype walking machines and met with very similar problems. In the main, I used 3 degrees of freedom on each leg. The most successful used three motors arranged in a triangle with flexible stainless wires forming a tripod, the motors lengthening &amp; shortening each of the wires - allowing the foot to move anywhere in 3D space. <br>Like you, one of the biggest issues was that each leg had to be capable of lifting most of the weight of the rest of the robot. The solution was to put the motors and batteries in the feet! The body only then had to provide structure &amp; control and could be very light. As you would typically have half the feet on the ground, the lifting requirement was lessened. Also with this arrangement, all three motors were used to lift 2 pulling wires &amp; 1 pushing. The flexibility in the wires made the kinematics easier too. <br>The one most significant thing I learned was that if you build a walking algorithm based on the positions of the feet - its easy to make it walk, but it looks very mechanical and clunky. If on the other hand you embrace the elasticity in the structure and sequence the movement by force (motor current) and duration but don't worry too much about the precise position of the actuators - it looks much more organic and copes better with uneven surfaces. <br>Best of luck in the continuation of the project! <br> <br>Si
You mention the Shadow Robot Company Arm with Hand is very mechanical and rigid, that is a poor demonstration. To see what air muscles can do watch the human sized leg i created for Shadow www.youtube.com/watch?v=A6BxMICmvc4&amp;list=UUoY1Roca-osK58wMvaqWqDw.
How much did it cost?
What part?
The whole thing.
Cool write up. I've gotten a lot of emotional responses to my frog-shaped amplifier: It doesn't move or respond otherwise, but I have been asked if i plan to sell or market it.
Those poor octopus! I wanted to jump in there and save the poor little guys. <br> <br>I've come to the same conclusion as you when it comes to the Objet prints, they are absolutely not meant for mechanical structures. Making molds and casting the parts is the only feasible way to make use of them, but that kind of removes the &quot;rapid&quot; from rapid prototyping, doesn't it. ABS is the way to go for functional 3D prints; cheaper, faster, stronger, plays well with other materials and adhesives. <br> <br>This reverse social robot concept, to provoke human response rather than other way around, I find this very fascinating. It would be a fun experiment to show groups of people the robot and then ask them what it was. Would they think it a squid, a spider, a marmoset, or something completely different. <br> <br>Great work, I can't wait to see whats next!
Asking people what they think it looks like is a good idea. I should have been doing that all along.
I think it's a dog, because of that last video with the front legs up and the back legs down. It looks like a dog sitting on it's haunches.
Nice! But I think you need to give each leg 2 motors. That way you get X and Y motion and each leg can move in a circular fashion the way a living centipede's legs move.
Yes. I concur. I think if I were to continue forward that is probably #2 on my list, next to removing the large amount of torsion in the joints. <br /> <br />My initial 3-jointed legs had this feature, but I scaled back considerably when I realized those would not work as designed.
Thanks :-)
I would probably use the 3D printing for a rough shape for a part, then refine it by hand (sanding it down, adding material to small crevices if need be), and use that as a positive to make a mold for the actual parts. Then I wouldn't be as limited in terms of materials used to make the actual parts. 3D printers still tend to cost more in terms of energy use and specific (usually costly) materials than the alternatives. I can see it being worthwhile to use a mold, especially when you need several of a particular part. <br> <br>I love your work here, but I think you're missing an angle. Your approach is perfectly formulaic, and I wouldn't suggest changing that. I think you might benefit, however, from an artist's perspective (one who understands biology and a bit about robotics, not some right brained pretentious twit). Generally speaking (and in my opinion), the best human creations have grown from a balanced composition of art and science. Mathematicians, for example, can find fascinating numerical patterns in great music, and well rounded neurological researchers could summarize why certain songs have positive effects on people. They can prove why great music works... but they're not often the ones who composed the original melodies. The artists who might not even understand basic geometry can still write a score filled with beautiful, perfect mathematical principles. Not all breakthroughs come from the &quot;99% perspiration&quot; side of things. I hate to see you abandon your research out of frustration. I'm not intending to minimize your tremendous work and research in this project at all... but I do wonder if maybe you would benefit from a completely unqualified opinion. And if you can't find a suitable artist in your area, I'll bet asking a classroom of 6-8 year olds to draw robotic tentacle/legs would produce some inspiring results. <br> <br>On a side note... perhaps you're just not nerdy enough these days, but since when is social interaction more important than complicated mechanisms? ;)
The 3D printing used here can produce a very wide range of materials at very high accuracy. It is like a pantone scale for hardness (from various types of soft rubber-like materials to hard rigid plastics). You can't really tell the part was made by 3D printing. I can cast straight from the material without any processing and get good results. The problem is that they are relatively complex structures to cast. I have rubber impregnated in rigid plastic structures. The printer just fuses the two materials in the printing process. That would be a multi-stage casting process and require a bit of a redesign to make a silicone 'cling' to the rigid plastic and not slip (or finding the right materials that fuse in casting). In this way, I think I used the right process. Also, I am fairly allergic to a lot of polyurethane casting materials, and try to avoid those. <br /> <br />To be fair, I don't really consider myself much of a scientist or engineer. I'm largely self-taught on the technical side of things. I made this as part of my MFA studio coursework. I showed this to my studio class consisting almost entirely of non-technical people and they tended to have little feedback to offer. At least not much feedback that I could do anything useful with. <br /> <br />My goal was to get fluidity of motion before being bogged down by aesthetic decisions. Besides, part of my hypothesis was also that it does not have to look like an organic form to be perceived as an organic form. Once I got the mechanics down, I would then play around with how lifelike I could make them. One of the nice things about the printers is that I could print all kinds of weird skins and textures over the framework. I just never got that far.
Very good information. Thank you.
You man did AMAZING job here, especially research about motion in nature! Love that! <br>Keep on going! <br>IMO, you should try made leg with 3 wires instead of 2. You will get more degrees of freedom, but of course, you will need more motors/servos to make it move. <br>Maybe You should consider rubber &quot;boots&quot; for each leg?
If the materials are unsuitable for hydraulics, why not try vacuum muscles instead? <br>
The PSI is too high for that. It would burst the material very quickly.
Really? <br> <br>Truck air-brake servos apparehtly work at no more than 1 or 2 psi below atmospheric pressure. <br> <br><sub>(source: http://www.amazon.com/Bazookas-Electric-Rainbow-Saturday-Projects/dp/0691009864/ref=sr_1_1?s=books&amp;ie=UTF8&amp;qid=1358194100&amp;sr=1-1&amp;keywords=vacuum+bazookas page 62)</sub>

About This Instructable




Bio: My name is Randy and I founded the Instructables Design Studio. I'm also the author of the books 'Simple Bots,' and '62 Projects to ... More »
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