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.
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.
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Signing UpStep 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:
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.
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"
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.
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Roz has a bunch of 3D printed parts, BTW. They were all printed in ABS on a Dimension uPrint printer.
Thumbs up, it's a magnificent Instructable and you went through a great process.
Y.
Thank you Randofo, excellent documentation!
I have some "constructive" 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.
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.
Just my thoughts.
Good luck with your project and I would love to see more design iterations of this robot.
Rob
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 & shortening each of the wires - allowing the foot to move anywhere in 3D space.
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 & 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 & 1 pushing. The flexibility in the wires made the kinematics easier too.
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.
Best of luck in the continuation of the project!
Si
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 "rapid" 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.
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.
Great work, I can't wait to see whats next!
My initial 3-jointed legs had this feature, but I scaled back considerably when I realized those would not work as designed.
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 "99% perspiration" 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.
On a side note... perhaps you're just not nerdy enough these days, but since when is social interaction more important than complicated mechanisms? ;)
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.
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.
Keep on going!
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.
Maybe You should consider rubber "boots" for each leg?
Truck air-brake servos apparehtly work at no more than 1 or 2 psi below atmospheric pressure.
(source: http://www.amazon.com/Bazookas-Electric-Rainbow-Saturday-Projects/dp/0691009864/ref=sr_1_1?s=books&ie=UTF8&qid=1358194100&sr=1-1&keywords=vacuum+bazookas page 62)