Unfolding Origami Engineering
There’s more to it than just paper cranes.
Origami (折り紙) — the ancient Japanese art of folding paper. The term “origami” comes from the Japanese words “ori” (to fold) and “kami” (paper). Traditionally, the art form utilizes a single sheet of paper (no cuts permitted) that is then manipulated and folded into infinite combinations of wonderful, complex, and masterful looking shapes.
Today, origami has transformed into more than just paper folding. Origami can be utilized as a solution to many applications in engineering, technology and medicine. Folding can be a great asset when space is limited and can be used as a compactly stowed system that transforms into a 3D structure with variable functionality. Origami can be reconfigured to change shape, functionality, and property. Because of the advances in computers and mathematics, more complex geometric folding algorithms are allowed for endless possibilities for applications in the fields of science, technology, and engineering.
Common crease patterns seen in origami engineering are the Miura-ori, Yoshimura, and the Diagonal patterns.
Other derivatives of origami also seen in engineering are Kirigami and Rigid origami.
Other useful origami terms:
Crease: A fold; Vertex: Where two creases intersect; Valley and Mountain: when paper is folded, a “V” shape is formed. Folding the paper up creates a “valley” while folding the paper downwards creates a “mountain”
Origami in Structural Applications
United we “stand”!
The 3D zipper tube, developed by researchers from the University of Illinois, the Georgia Institute of Technology and the University of Tokyo consists of two zigzag pieces of paper that are glue together. Although a single strip of paper is pretty flexible by itself, they can be combined to create a tube in an interlocking manner. This produces a structure with a very high degree of stiffness, resilience and strength. Other thin materials such as plastic or metal can be used as well and can be made as large as a building or microscopically small.
These tubes can actually be combined into many unique geometries and angles, forming different three-dimensional structures for different purposes, such as a bridge or a building. With a huge range of diversity in transformable geometry, their functionalities can be easily and quickly altered, making them very adaptable to every situation and environment. This could lead for a great potential in quick assembly of emergency shelters and natural disaster relief.
The physical properties and structure can be altered and defined based on the many possible geometries, making them very easily configurable and can be made softer or stiffer depending on the intended use.
The researchers are currently exploring new combinations and angles of tube to build different structures. By applying these techniques to new material, different applications can be explored ranging from construction to microscopic structures.
On a personal note, this actually reminds me of the instant buildings from the 2009 animated film, Meet The Robinsons. It sort of made me think about what would happen if the building were to contract back again with people still inside it. Yikes. Pop up buildings anyone?
Origami in Medical Applications
Ever wonder how it feels to have something crawl inside your stomach?
As a small kid growing up, I watched this documentary about viruses and intestinal parasites. There was this one part about removing these intestinal parasites via an operation, And man did it scar me for quite some time. Because of this, I would always freak out whenever I saw blood on the chicken wings that I just ate. Why? Because I always had that fear of growing intestinal parasites because of the undercooked meat (I was like five years old at the time, it wasn’t as if I was some biology expert) and I would constantly try to feel my stomach for any sort of parasite movement. The worst feeling would be having a stomach ache right after eating meat because I legitimately thought I would be eaten inside out by parasites.
Well, here I am now, alive, not a vegan and eating my mom’s home-made *cooked* steamed chicken drumstick while writing this article.
On a similarly related topic, one of the latest development of origami in the medical fields comes from a collaborative effort from MIT, the University of Sheffield, and the Tokyo Institute of Technology lead by MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) Professor Daniela Rus, has developed a small and ingestible origami bot. This origami bot can unfold itself from a swallowed ice capsule that would be tasked to patched wounds and digested button batteries or deliver medicine at designated locations.
A permanent magnet is placed in the center between two folds. This magnet is used to control the robot as it responds to the varying changes of external magnetic fields outside the patient’s body. The bot propels itself using a “stick-slip” form of motion in which the bots appendages stick to a surface of friction when it performs a move, then slips free when the body flexes due to the change in weight distribution. It is also noted that due to the presence of stomach fluids, the bot doesn’t entirely rely on the “stick-slip” motion, “In our calculation, 20 percent of forward motion is by propelling water — thrust — and 80 percent is by stick-slip motion,” says Shuhei Miyashita, a former postdoc at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL).
“ShuHei bought a piece of ham, and he put the battery on the ham,” stated Rus. “Within half an hour, the battery was fully submerged in the ham. So that made me realize that, yes, this is important. If you have a battery in your body, you really want it out as soon as possible”
Each year, about 3500 button batteries are reported to be swallowed in the States alone.
This being said, once a button battery comes into prolonged contact with the esophagus or stomach tissue, the battery can cause an electric current that produces hydroxide, which burns body tissue. This is where another functionality of the magnet comes to play: picking up button batteries and disposing them through the digestive system.
Of course, the bot itself isn’t made out of paper. A challenge with designing the bot itself came from finding the right biocompatible material. Additionally, for the “stick-slip” motion to work, the biocompatible material has to be stiff in order to prevent it from completely collapsing while performing tasks within the body. “We spent a lot o time at Asian markets in Chinatown” , says team member Shuguang Li, a postdoc in Professor Daniela Rus’s research group. In the end, dried pig intestine used in sausage casings was opted as the material of choice.
Future developments with regards to the origami bot include adding sensors and removing the need for an external magnetic field. As of now, the bot isn’t exactly human-ready yet and rigorous tests are still being performed. Maybe one day, we might be able to have a whole ecosystem of robots inside our bodies performing tasks and curing diseases!
Origami in Astronautical Applications
The mysteries of the universe could soon be unfolded
It requires a lot of energy to support a manned mission to Mars or even the distant reaches of space. It may sound a bit far fetched, but it can soon be made possible with origami-inspired engineering. Using today’s techniques, sending a spacecraft into space requires a lot of money — a massive 10,000 dollars per pound of payload into earth’s orbit, which is an obvious limitation when government space agencies like NASA are on such a budget. Moreover, we can only fit so much into a rocket. To support all the inhabitants and other power-consuming equipment, the International Space Station houses 8 solar arrays, each measuring 73 meters in length. How can a single rocket fit all that? It doesn’t. No rocket ever made thus far is strong or large enough to take 8 huge solar arrays into space. Instead, It took multiple missions over the decades to build and to install all the solar arrays. This method is both costly and time-consuming.
Current space technology uses nuclear energy to power spacecrafts. Chemical and ion propulsion systems are commonly used, a fuel source that will eventually run out. These fuel sources could only so long under constant use, such as for collecting data and beaming back information back to earth. The space longest mission to date are the Voyager spacecraft, as they are reaching 40 years in space. They are primarily nuclear powered, so their source of power will run out within the next year or so. Imagine being able to combine both nuclear energy and solar energy as an energy source, spacecraft missions could last up to fifty to a hundred years according to Shannon Zirbel, a former Ph.D. student in mechanical engineering at Brigham Young University. The future of spaceflight and exploration may one day rely on the traditional art of origami.
Conventional solar arrays used today consists of a series of rectangular segments that folds out like an accordion once launched into space. Because of the volume constraints in rocket payload, the size of these arrays are limited. With a more complex folding pattern, a large stowed to deployed ratio can fit compactly into a rocket to enable maximum cargo space (volume) to energy production ratio.
A NASA research announcement called for a solar array with a large stowed-to-deployed ratio diameter and a power requirement of at least 250 kilowatts. Using the principles of origami and a mixture of different styles of folds, a new type of origami-inspired solar array was created. Brian Trease, a mechanical engineer at Nasa’s Jet Propulsion Laboratory has teamed up with researchers at Brigham Young University and Origami expert Robert Lang to create an origami-inspired solar array — a “no-astronaut-assembly-required” design that opens automatically once the spacecraft is in space. A 1/20th scale model of the array is currently under the prototyping stages with a deployed-to-stowed diameter ratio of 9.2 (1.25 meter deployed and 0.136 stowed). Once complete, the 2.7 meters wide solar array would wrap around a spacecraft and will expand to 25 meters in diameter when deployed. An origami solar array that size could produce up to 250 kilowatts of power, compared to the 84–120 kilowatts all the solar arrays combined on the International Space Station could produce.
A statement from JPL states :
“One technique (in a combination of different folds) that has been used for an origami-inspired solar array is called a Miura fold. This well-known origami fold was invented by Japanese astrophysicist Koryo Miura. When you open the structure, it appears to be divided evenly into a checkerboard of parallelograms. It looks like a blooming flower that expands into a large flat circular surface”
The design of the unfolded solar array mimics flower with six sides with multiple layers of valleys and mountains that can be continuously added to increase the diameter. The thickness of the arrays itself governs the final size of the stowed model. The genius of this design is that the height constraints of the stowed array do not limit the deployed diameter. Many methods of deployment were placed into consideration, such as using pneumatic actuation, centripetal acceleration, stored strain energy, and thermal activation. It was soon concluded that a motor-driven perimeter truss would most likely be used in the final model.
But designing a 25 meter diameter solar array requires some clever engineering. Mathematical models will always assume zero thickness of material, meaning that if the material were folded and stacked together, they would be coplanar. But when material with finite thickness is used, like the origami solar array, stacking them together would not produce a mathematically coplanar result. In layman terms, each bend causes the thickness of the folds to increase. To accommodate for this, the method of rigid-foldable origami is applied to where the facets are replaced with rigid panels and the creases replaced with hinges (or something similar), giving finite spacing between the folds. This creates a linear piecewise curve in the folding pattern (creases) itself.
In the final model of the array, a membrane backing was selected to connect the solar panels together. To enable rigid foldability (where the folding is to take place between the membrane joints), valley folds are given a gap of 10 to 14 times the thickness of the solar panels while mountain folds are given minimal space to maximize the surface area of the solar array itself.
The first Miura-based solar array was also used in the 1995 Japanese Space flyer Unit, but the technology was still a rather early concept at the time and was still under a lot of development and research.
Simple folded solar arrays are already in use in space missions, but Brian and his team intend to find a more efficient and effective way of incorporating folding mechanisms in these “origami” space arrays. Solar arrays aren’t the only ones in the space industry that can make use of origami engineering: solar sails, space equipment, robotics and even a expandable spacecraft could make use of origami.
Maybe for now, I think I’ll stick to my Senbazuru project.
