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## Butterfly Ornithopter

I came across a very cool video today morning and that gives this post its name. Before I get into that, I think it would be much desirable to give an introduction to Ornithopters in general and talk about some robotic ornithopters. For those interested solely in the video, well it is at the end of the post (second last video).

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Introduction

An Ornithopter basically means an aircraft (even a robot) that can fly by flapping its wings. Though the word might sound complicated initially (Although the prefix Ornith- is well known). All of us at some point in time (whether as a childhood fantasy or as a serious hobby or professional work) have wanted Ornithopters. Ornithopters have been a fantasy since very ancient times, and it is obvious to have been as birds have always fascinated and amazed humans. There have been many reported Ornithopters in Hindu mythology. Also the legend of Daedalus and Icarus is well known, in which Daedalus designed feathered wings to fly out of the island of Crete on to which he was imprisoned.

The legendary Leonardo Da Vinci – A genius  imprisoned in a time where his ideas just could not have been realized, made some designs of Ornithopters and other glider type flying machines (but let’s avoid machines that do not have any moving wings in this post, though some are very cool). Some of which were very good engineering designs.

Click to Enlarge

Though we tend to regard the idea of wing powered machines as failed because of the success of modern day style aircraft there have been many successful flights. The first reported to have flown successfully was made in 1929 by Alexander Lippisch, it flew about 300 meters before the flight was terminated due to the obvious limitations of human muscle power. A number of motorized ornithopters have been made since then. A number of people take  Ornithopters as a serious hobby.

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Modern Ornithopters

These days though, the interest has been more in ornithopters that resemble insects, such as bees, both as toys and sophisticated autonomous flying spy robots. The size of such Miniature Aerial Vehicles would ensure they are impossible to detect and hence are perfect for spying missions. Especially in the case of urban warfare when the opposing party might be holed up in a building. Thus, needless to say these can be very helpful in counter-terror operations. The aim in making such bots would be to make them very low cost with flight times as high as 5-6 hours. Let me cite some examples of some cool miniature aerial vehicles of the ornithopter category.

After some early feasibility studies done at the Lincoln laboratories at the MIT, DARPA in 1997 began a multi-million dollar program to make some sophisticated Miniature Aerial Vehicles (MAVs), some of the designs and projects also included ornithopters.

One such ornithopter was the MicroBat ornithopter developed at the California Institute of Technology along with AeroVironment and UCLA.

[The MicroBat Ornithopter, Image Source]

This paper reports the making  of the MicroBat Ornithopter. The excerpt to the paper:

This paper reports the successful development of “Microbat,” the first electrically powered palm-sized ornithopter. This first prototype was flown for 9 seconds in October 1998. It was powered by two 1-farad super capacitors. Due to the rapid discharge of the capacitor power source, the flight duration was limited. To achieve a longer flight, a rechargeable battery as a power source is preferred. The second prototype houses a small 3-gram rechargeable Ni-Cad battery. The best flight performance for this prototype lasted 22 seconds. The latest and current prototype is radio-controlled and is capable of turning left or right, pitching up or down. It weighs approximately 12.5 grams. So far, the best flight duration achieved is 42 seconds. The paper also discusses the study of flapping-wing flight in the wind tunnel using wings developed by MEMS technology. This enables a better understanding the key elements in developing efficient wings to achieve aerodynamic advantage in flapping-wing flight.

Another research group led by Robert C. Michelson made another Ornithopter called the Entomopter. This went one step ahead and can be called a milestone in MAV ornithopter development. The aim was to closely mimick the flight of birds and thus totally eliminate the usage of gears and motors. The entomopter is driven by wings that are driven by a reciprocating chemical muscle.

Click to Enlarge

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Ornithopter Toys

There are now a number of companies that offer ornithopter toys. One of the most well known probably is the FlyTech Dragonfly from WowWee, It is a remote controlled wireless ornithopter. It seems like a pretty fun toy. You can see a video on this toy here >>

[FlyTech DragonFly Ornithopter]

A number of people take making ornithopters as a very serious hobby. If you wish to make one, then I would direct you to this page.

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Butterfly Ornithopter

Finally I come to the part that gave this blog post its title. ;-)

In a paper at IROS 2008, researchers from the Shimoyama – Matsumoto Lab at the university of Tokyo presented their work on an extremely light butterfly ornithopter.

[Butterfly Ornithopter: Image Source]

The artificial butterfly wing consists of a thin polymer membrane which is supported by viens of plastic having rectangular cross section. The purpose of this paper was to study the effect of veins on the performance of flight. The parameters for this “butterfly” are more or less comparable to that of an actual butterfly.The weight of the ornithopter including the wings is just about 0.39 gms and the flapping frequency 10 Hz.

Here is a fantastic video of the Ornithopter depicted in the figure above:

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Some more work on Ornithopters at Shimoyama – Matsumoto Lab:

Since I have just mentioned the work on the Butterfly Ornithopter, there is some cool work going at the Shimoyama – Matsumoto Lab on ornithopters.

[Hovering Type Ornithopter: Image Source]

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Bio-Inspired Flying Robots

Finally before ending, I would like to post a bonus video ;-)

This video was the winner at the AAAI – 08 video contest. Like the video on Morphogenesis (Swarm Intelligence) which I posted about 10 months back, which was also a winner in the same contest, this video too is excellent.

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1. MAVSTAR – Micro Aerial Vehicles for Search Tracking and Reconnaissance.

3. Nano Air Vehicle – DARPA

4. Ornithopter Zone – Excellent site for the hobbyist.

5.  Project Ornithopter – Project on making Ornithopters on a much larger scale than those discussed in this post.

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Onionesque Reality Home >>

While searching for some methods for face representation in connection with my recent project, I lost the way clicking on some stray links and landed up on some beautiful art work involving Voronoi diagrams. I was aware of art work based on Voronoi diagrams (it kind of follows naturally that Voronoi diagrams can lead to very elegant designs, isn’t it?) but a couple of images on them were enough to re-ignite interest. It was also interesting to see an alternate solution to my problem based on Voronoi diagrams as well. However I intend to share some of the art work I came across.

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Before I get to the actual art-work I suppose it would be handy to give a very basic introduction to Voronoi Diagrams with a couple of handy applications.

Introduction: Voronoi diagrams are named after Georgy Voronoy (1868-1908), an eminent Russian/Ukrainian mathematician. A number of mathematicians before Voronoy such as Descartes and Dirichlet have been known to have used them, Voronoy extended the idea to $\mathcal{N}$ dimensions. The Voronoi diagram is a tessellation, or a tiling. A tiling of a plane is simply a collection of plane figures that fills the plane with no overlaps and no gaps in between. This idea can ofcourse be extended to $\mathcal{N}$ dimensions, but for simplicity let us stick with 2 dimensions.

[A pavement Tessellation/Tiling]

Definition: A Voronoi diagram is a special kind of a decomposition of a metric space which is determined by a discrete set of points.

Generally speaking for a 2-D case:

>> Let us designate a set of $n$ distinct points that we call sites as $\mathcal{P}$. i.e $\mathcal{P}=\{P_1, P_2\ldots, P_n\}$

>> We may then define the Voronoi Diagram of P as a collection $\mathcal{V}=\{V_1,V_2,\ldots, V_n\}$ of subsets of the plane. These subsets are called as Voronoi Regions. Each point in $V_i$ is such that it is closer to $\mathcal{P}_i$ than any other point in $\mathcal{P}$.

To be more precise:

A point $Q$ lies in the Voronoi Region corresponding to a site $P_i \in \mathcal{P}$ if and only if –

$Euclidean\_Distance(Q,P_i) < Euclidean\_Distance(Q,P_j)$ for each $P_i \neq P_j$

However it might be the case that there are some points in the plane that might have more than one site that is the closest to it. These points do not lie in either Voronoi Region, but simply lie on the boundary of two adjacent regions. All such points form a skeleton of lines that is called the Voronoi Skeleton of $\mathcal{P}$.

We can say that $\mathcal{V(P)}$ is the Voronoi Transform, that transforms a set of discrete points (sites) into a Voronoi Diagram.

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For more clarity on the above, consider a sample Voronoi Diagram below:

The dots are called the Sites. The Voronoi Regions are simply areas around a site but enclosed by the lines around them. The network of lines is simply the Voronoi Skeleton.

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Some Extensions to the above Definition: The above definition which is ofcourse extremely simple can be extended very easily[1] for getting some fun art forms.

Some of these extensions could be as follows [1]:

1. Since each region corresponds to a site, each site can be associated with a color. Hence the Voronoi diagram can be colored accordingly.

2. In the definition the sites were considered to be simply points, we can obtain a variety of figures by allowing the “sites” to be subsets of the plane than just points. We see, that if the sites are defined as simply points, the Voronoi skeleton would always be composed of straight lines. With this change there could be interesting skeletal figures emerging.

3. We could also modify the distance metric from the Euclidean distance to some other to get some very interesting figures.

This just shows the kind of variety of figures that can be generated by just a small change in one aspect of the basic definition.

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Constructing a Voronoi Diagram:

Let us forget the extensions that we spoke of for a moment and come back to the basic definition. Looking at the definition it  seems constructing Voronoi diagrams is a simple process. And it is not difficult at all. The steps are as follows:

1. Consider a random set of points.

2. Connect ALL of these points by straight lines.

3. Draw a perpendicular bisector to EACH of these connecting lines.

4. Now select pieces that are formed, such that each site (point) is encapsulated.

Voronoi Diagrams can be very easily made by direct commands in both MATLAB and MATHEMATICA.

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Voronoi Diagrams in Nature: It is interesting to see how often Voronoi diagrams occur in nature. Just consider two examples:

[Left: Reticulum Plasmatique (Image Source) Right: Polygons on Giraffes]

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Uses of Voronoi Diagrams: There are a wide variety of applications of Voronoi diagrams. They are more important then what one might come to believe. Some of the applications are as follows:

1. Nearest Neighbour Search: This is the most obvious application of Voronoi Diagrams.

2. Facility Location: The example that is often quoted in this case is the example of choosing where to place a new Antenna in case of cellular mobile systems and similarly deciding the location of a new McDonalds given a number of them already exist in the city.

3. Path Planning: Suppose one models the sites as obstacles, then they can be used to determine the best path (a path that stays at a maximum distance from all obstacles or sites).

There are a number of other applications, such as in Geophysics, Metrology, Computer Graphics, Epidemiology and even pattern recognition. A very good example that illustrates how they can be used was the analysis of the Cholera epidemic in London in 1854, in which physician John Snow determined a very strong correlation of deaths with proximity to a particular infected pump (specific example from Wolfram Mathworld).

Let’s consider the specific example of path planning [2]. Consider a robot placed in one corner of a room with stuff dispersed around.

Now the best path from the point where the robot is located to the goal would be the one in which the robot is farthest from the nearest obstacle at any point in time. To find such a path, the Voronoi diagram of the room would be required to be found out. Once it is done, the vertices or the skeleton of the Voronoi Diagram provides the best path. Which path ultimately is to be taken can be found out by comparing the various options (alternative paths) by using search algorithms.

Now finally after the background on Voronoi Diagrams let’s look at some cool artwork that i came across. ;-)

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Fractals from Voronoi Diagrams:

This I came across on the page of Kim Sherriff[3]. The idea is straightforward to say the least.

It is: To create a fractal, first create a Voronoi diagram from some points, next add more points and then create the Voronoi diagrams inside individual Voronoi Regions. Some sample progression could be like this:

Repeating the above process recursively on the above would give the following Voronoi fractal.

Interestingly, this fractal looks like the structure of a leaf.

The above was repeated in color by Frederik Vanhoutte[4] to get some spectacular results. Also I would highly recommend his blog!

[Voronoi Fractal – Image Source]

I am really going to try this myself, it seems a few hours of work at first sight. Ofcourse I won’t use the code that the author has provided. ;-)

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Mosaic Images Using Voronoi Diagrams[5] :

I have not had the time to read this paper. However, I am always attracted by mosaics, and these ones (the ones in the paper) as created using Voronoi Diagrams have an increased coolness quotient for me. Sample this image:

Golan Levin’s[6] experiments in using Voronoi diagrams to obtain aesthetic forms yielded probably even more pleasant results. The ones below give a very delicate look to their subjects.

The tilings that are produced by just mild tweaks to the basic definition of a Voronoi Diagram for a 2-D case that I had talked about earlier can give rise to a variety of tilings. Say like the one below:

Also, today I came across a nice Voronoi Diagram on The Reference Frame:

The diagram is a representation of 17,168 weather stations around the world. Dr Motl illustrates how handy MATHEMATICA is for such things.

Click to Enlarge

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References:

[1] Craig Kaplan, Voronoi Diagrams and Ornamental Design.

[2] Introduction to Voronoi Diagrams – Example.

[3] Kim Sherriff, “Fractals from Voronoi Diagrams“.

[4] Frederik Vanhoutte, “Voronoi Fractal“.

[6] Golan Levin, “Segmentation and Symptom

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Applets:

2. Bubble Harp.

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Onionesque Reality Home >>

## Rotundus the Spherical Robot

The idea of spherical robots is not new, however they are still interesting and Rotundus, the spherical robot that happened to be in the Popular Science best of ’08 is very interesting.

[Groundbot, Image Soure: PopSci]

Click to Enlarge

The Rotundus is driven by a pendulum inside the spherical casing. This pendulum controlled by a motor gives the robot direction. Getting the pendulum to move forward makes the robot to roll forward and moving it left or right gives it the ability to steer. The makers of this robot hope to make it autonomous with improvements. They hope to integrate in it a GPS so that it can follow specified routes to patrol and to incorporate radar sensors to help move about obstacles. They also plan to give it sufficient power to move up on slopes.

[Rotundus: Image Source]

From Popular Science:

The GroundBot is a spherical sentry designed to roll up to 6 mph through just about anything—mud, sand, snow and even water. Two gyroscopically steadied wide-angle cameras and a suite of sensors give remote operators a real-time, 360-degree view of the landscape, letting them zoom in on prowlers or detect gas leaks, radioactivity and biohazards. Originally invented by Swedish physicists to explore other planets, the GroundBot features a tough design that requires almost no maintenance and can also be programmed to run autonomously. Its sealed shell protects its interior against grit and allows it to survive steep drops, while a rubber skin dampens vibration and provides traction. To get rolling, the robot simply shifts its weight. Its center of mass is suspended from a pendulum inside the sphere, so motors just push the pendulum to the front, to the back, or to the side. Lithium-ion batteries provide up to 16 hours of spy time.

The advantages of a spherical robot are manifold, its design is extremely non-complicated. It offers good protection to the sensors and equipment sealed inside the sphere. Rotundus is very light, just about 25 Kilos, but the low weight advantage is multiplied as the rotundus is sealed. That means that it has a low density and can thus float. Thus it may be used to operate on-road, off-road and over water! Sealing the bot has other advantages than simply allowing the robot to have low density so that it can float, it also ensures that no sand can get inside to interfere with the motors and etc. The sealing also makes the robot of good use in gas leak scenarios as electrical sparks (if any) in the inside are sealed off. The design also makes the robot a very silent operator.

Check the following video showing the Rotundus roll along in snow:

A group of Rotundus robots may be used as helper bots along with the new Mars rover, the SUV sized Mars Research Laboratory that is expected to be launched by next fall.

The Rotundus has some obvious limitations. Like it can’t operate properly inside buildings as it can’t move up stairs. For such purposes biologically inspired bots remain the best bet IMO. See some of them here, really cool research:

1. Rotundus

Onionesque Reality Home >>

## Problems with Orion like projects

The old Orion project had a few potential problems. There were doubts regarding the stability of the system, but with modern simulation technology this can be verified rather easily and without the need for an actual empirical investigation. The main problem however was the possible nuclear fallout. This was the most important reason due to which the project was shelved. The treaty of 1963 came as the final blow.

Even with the newer “versions” of Orion like projects there are all sorts of problems.

While the Orion was important for its time (in terms of stimulating possible engineering concepts), I would currently view it as “post period”.
A better possible concept is when will we have the technology to effectively observe “everything”? If you can observe it you do not have to “go there”. There are of course limits, and of course these should be discussed. But current planned satellites allow us to “go there” much more effectively without the need for an Orion like project.

I believe the Mars rovers can provide a good example of how to do things now. They have lasted something like 2-3 years longer than their design life. So long as one builds in fault tolerance bots could have even longer lifetimes.
We are not going to really get there until we have true nanorobots that can be organized to operate collectively because these can be launched with very small rockets.

The solution to managing things is what is known as a “broadcast architecture” (which is very similar to what NASA uses now with satellites but on a somewhat larger scale).

Even with the mini-mag there are problems. First, basing a propulsion system on 245 Cm presumes that you could synthesize sufficient amounts of it. That is a massive undertaking.

Second, it assumes one needs to navigate 100ton spaceships around the solar system. We do not. We need to be able to launch nanorobots into orbits that can easily be transported to various places in the solar system to manage development. That requires lots of micro-rockets — not the huge spaceships designed to transport humans to places they were they are not adapted to live. This i have already touched upon in the previous paragraph. The paper (cited in the previous entry) is a classic example of good physicists doing good work who have little understanding of nanotechnology or microbiology. They also are stuck in 1960’s era concepts that “we” should go there when we have to completely alter the human genome before we should even consider that. And by then we will likely be dead or uploaded and so it is pointless to attempt 1960’s era transport of us.

Related Articles:

Death of a project: Project Orion

Possible Rebirth of Project Orion?

Morphogenesis and Swarm Robotics

Onionesque Reality Home >>

## Robots Inspired by Animals

There have been quite a few posts on nature inspired computing. Here is another, this is a really cool video on the same. Have a look at the gait of the yellow salamander mimic bot and also the caterpillar bot at the end of the video!

Have fun!

The introduction to this video reads as:

Robotics researchers are increasingly turning to nature for inspiration. Watch a robotic salamander, a water strider robot, mechanical cockroaches and some cool self-configuring robots.

Footage courtesy of: University of Essex, Ecole Polytechnique Federale de Lausanne, Carnegie Mellon University, ULB-EPFL, Tokyo Institute of Technology, National Institute of Advanced Science and Technology (AIST).

My congratulations and best wishes to the researchers who are trying to develop such bots and also to New Scientist for such a good video!

## Morphogenesis and Swarm Robotics

Here is an amazing video!

An introduction to swarm intelligence, swarm robotics and morphogenesis. This video won the Best Video award at the AAAI-07 conference Vancouver Canada. The scientific research was performed by Anders Lyhne Christsensen, Rehan O’Grady and Marco Dorigo. The video was directed by Andreia Onofre.

Swarm Intelligence is an AI technique that is based on the collective behavior of decentralised and self organised systems. Take an ant colony for example, an ant hill is an extremely complex structure, with even things like temperature control in place. It is difficult to imagine a simple ant doing any of it! So it is basically the “swarm” of ants that is responsible for such emergent and intelligent solutions though the “constituents” of the systems (i.e ants) are simple and independent “units”. Like ants also can pick up prey many times their weight by forming very precise structures encircling the object under consideration.

like in the picture below the ants take up a comparatively much heavier fly.

photo credit with full regards : here>>

The video basically explains the same and also gives an idea on how it could be done using robots. For example a bird swarm can make very different and complex shapes depending on the set of rules under use (which in turn will depend on the scenario). I will accompany this statement by a post on a bird swarm and how they do it sometime soon. If you change the set of rules you could change the shape you get, and most of these shapes could be used to perform some intelligent task. This gives the swarm a lot of flexibility. This is basically what is Morphogenesis.

Morphogenesis could be used by a swarm of robots to move heavy objects (as an illustration to this have a look at this video, in which a group of robots pull away a child. The video can be seen here>>) which could be used in fire-fighting applications etc, to bridge gaps etc. A swarm of nano-bots could use morphogenesis to perform very specific tasks inside the human body!

Please have a look at this award winning video!

I personally thank and congratulate the director of this video for putting it all so succinctly in a matter of under 5 minutes.

## Monkey makes Robot move with the power of thought!

This post is as a follow-up to the previous post.

If Idoya could talk she would have plenty to boast about!

On Thursday, the 12-pound, 32-inch monkey made a 200-pound, 5-foot humanoid robot walk on a treadmill using only her brain activity.

“They should be able to move the arm with their thoughts,” he said. “This is science fiction coming to life.”

The complete news about the pivotal event can be read here>> complete with videos and pictures. The above illustration is also credited to the NY times. I would recommend the complete article!