INDIAN FIELDING
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TOOLS AND TECHNIQUES
[edit] Tools and techniques
Typical AFM setup. A microfabricated cantilever with a sharp tip is deflected by features on a sample surface, much like in a phonograph but on a much smaller scale. A laser beam reflects off the backside of the cantilever into a set of photodetectors, allowing the deflection to be measured and assembled into an image of the surface.
The first observations and size measurements of nano-particles was made during the first decade of the 20th century. They are mostly associated with the name of Zsigmondy who made detail study of gold sols and other nanomaterials with sizes down to 10 nm and less. He published a book in 1914. [19]. He used ultramicroscope that employes dark field method for seeing particles with sizes much less than light wavelength.
There are traditional techniques developed during 20th century in Interface and Colloid Science for characterizing nanomaterials. These are widely used for first generation passive nanomaterials specified in the next section.
These methods include several different techniques for characterizing particle size distribution. This characterization is imperative because many materials that are expected to be nano-sized are actually aggregated in solutions. Some of methods are based on light scattering. Other apply ultrasound, such as ultrasound attenuation spectroscopy for testing concentrated nano-dispersions and microemulsions [20].
There is also a group of traditional techniques for characterizing surface charge or zeta potential of nano-particles in solutions. These information is required for proper system stabilzation, preventing its aggregation or flocculation. These methods include microelectrophoresis, electrophoretic light scattering and electroacoustics. The last one, for instance colloid vibration current method is suitable for characterizing concentrated systems.
Next group of nanotechnological techniques include those used for fabrication of nanowires, those used in semiconductor fabrication such as deep ultraviolet lithography, electron beam lithography, focused ion beam machining, nanoimprint lithography, atomic layer deposition, and molecular vapor deposition, and further including molecular self-assembly techniques such as those employing di-block copolymers. However, all of these techniques preceded the nanotech era, and are extensions in the development of scientific advancements rather than techniques which were devised with the sole purpose of creating nanotechnology and which were results of nanotechnology research.
There are several important modern developments. The atomic force microscope (AFM) and the Scanning Tunneling Microscope (STM) are two early versions of scanning probes that launched nanotechnology. There are other types of scanning probe microscopy, all flowing from the ideas of the scanning confocal microscope developed by Marvin Minsky in 1961 and the scanning acoustic microscope (SAM) developed by Calvin Quate and coworkers in the 1970s, that made it possible to see structures at the nanoscale. The tip of a scanning probe can also be used to manipulate nanostructures (a process called positional assembly). Feature-oriented scanning-positioning methodology suggested by Rostislav Lapshin appears to be a promising way to implement these nanomanipulations in automatic mode. However, this is still a slow process because of low scanning velocity of the microscope. Various techniques of nanolithography such as dip pen nanolithography, electron beam lithography or nanoimprint lithography were also developed. Lithography is a top-down fabrication technique where a bulk material is reduced in size to nanoscale pattern.
The top-down approach anticipates nanodevices that must be built piece by piece in stages, much as manufactured items are currently made. Scanning probe microscopy is an important technique both for characterization and synthesis of nanomaterials. Atomic force microscopes and scanning tunneling microscopes can be used to look at surfaces and to move atoms around. By designing different tips for these microscopes, they can be used for carving out structures on surfaces and to help guide self-assembling structures. By using, for example, feature-oriented scanning-positioning approach, atoms can be moved around on a surface with scanning probe microscopy techniques. At present, it is expensive and time-consuming for mass production but very suitable for laboratory experimentation.
In contrast, bottom-up techniques build or grow larger structures atom by atom or molecule by molecule. These techniques include chemical synthesis, self-assembly and positional assembly. Another variation of the bottom-up approach is molecular beam epitaxy or MBE. Researchers at Bell Telephone Laboratories like John R. Arthur. Alfred Y. Cho, and Art C. Gossard developed and implemented MBE as a research tool in the late 1960s and 1970s. Samples made by MBE were key to the discovery of the fractional quantum Hall effect for which the 1998 Nobel Prize in Physics was awarded. MBE allows scientists to lay down atomically-precise layers of atoms and, in the process, build up complex structures. Important for research on semiconductors, MBE is also widely used to make samples and devices for the newly emerging field of spintronics.
Newer techniques such as Dual Polarisation Interferometry are enabling scientists to measure quantitatively the molecular interactions that take place at the nano-scale.
Applications
Main article: List of nanotechnology applications
Cancer
The small size of nanoparticles endows them with properties that can be very useful in oncology, particularly in imaging. Quantum dots (nanoparticles with quantum confinement properties, such as size-tunable light emission), when used in conjunction with MRI (magnetic resonance imaging), can produce exceptional images of tumor sites. These nanoparticles are much brighter than organic dyes and only need one light source for excitation. This means that the use of fluorescent quantum dots could produce a higher contrast image and at a lower cost than today's organic dyes. Another nanoproperty, high surface area to volume ratio, allows many functional groups to be attached to a nanoparticle, which can seek out and bind to certain tumor cells. Additionally, the small size of nanoparticles (10 to 100 nanometers), allows them to preferentially accumulate at tumor sites (because tumors lack an effective lymphatic drainage system). A very exciting research question is how to make these imaging nanoparticles do more things for cancer. For instance, is it possible to manufacture multifunctional nanoparticles that would detect, image, and then proceed to treat a tumor? This question is currently under vigorous investigation; the answer to which could shape the future of cancer treatment.[21]
Other
Although there has been much hype about the potential applications of nanotechnology, most current commercialized applications are limited to the use of "first generation" passive nanomaterials. These include titanium dioxide nanoparticles in sunscreen, cosmetics and some food products; silver nanoparticles in food packaging, clothing, disinfectants and household appliances; zinc oxide nanoparticles in sunscreens and cosmetics, surface coatings, paints and outdoor furniture varnishes; and cerium oxide nanoparticles as a fuel catalyst. The Woodrow Wilson Center for International Scholars' Project on Emerging Nanotechnologies hosts an inventory of consumer products which now contain nanomaterials.[22]
However further applications which require actual manipulation or arrangement of nanoscale components await further research. Though technologies currently branded with the term 'nano' are sometimes little related to and fall far short of the most ambitious and transformative technological goals of the sort in molecular manufacturing proposals, the term still connotes such ideas. Thus there may be a danger that a "nano bubble" will form, or is forming already, from the use of the term by scientists and entrepreneurs to garner funding, regardless of interest in the transformative possibilities of more ambitious and far-sighted work.
The National Science Foundation (a major source of funding for nanotechnology in the United States) funded researcher David Berube to study the field of nanotechnology. His findings are published in the monograph “Nano-Hype: The Truth Behind the Nanotechnology Buzz". This published study (with a foreword by Mihail Roco, Senior Advisor for Nanotechnology at the National Science Foundation) concludes that much of what is sold as “nanotechnology” is in fact a recasting of straightforward materials science, which is leading to a “nanotech industry built solely on selling nanotubes, nanowires, and the like” which will “end up with a few suppliers selling low margin products in huge volumes."
Another large and beneficial outcome of nanotechnology is the production of potable water through the means of nanofiltration. Where much of the developing world lacks access to reliable water sources, nanotechnology may alleviate these issues upon further testing as have been performed in countries, such as South Africa. It is important that solute levels in water sources are maintained and reached to provide necessary nutrients to people. And in turn, further testing would be pertinent so as to measure for any signs of nanotoxicology and any negative affects to any and all biological creatures. [23]
In 1999, the ultimate CMOS transistor developed at the Laboratory for Economics and Information Technology in Grenoble, France, tested the limits of the principles of the MOSFET transistor with a diameter of 18 nm (approximately 70 atoms placed side by side). This was almost 10 times smaller than the smallest industrial transistor in 2003 (130 nm in 2003, 90 nm in 2004 and 65 nm in 2005). It enabled the theoretical integration of seven billion junctions on a €1 coin. However, the CMOS transistor, which was created in 1999, was not a simple research experiment to study how CMOS technology functions, but rather a demonstration of how this technology functions now that we ourselves are getting ever closer to working on a molecular scale. Today it would be impossible to master the coordinated assembly of a large number of these transistors on a circuit and it would also be impossible to create this on an industrial level.
Implications:
Main article: Implications of nanotechnology
Due to the far-ranging claims that have been made about potential applications of nanotechnology, a number of concerns have been raised about what effects these will have on our society if realized, and what action if any is appropriate to mitigate these risks.
One area of concern is the effect that industrial-scale manufacturing and use of nanomaterials would have on human health and the environment, as suggested by nanotoxicology research. Groups such as the Center for Responsible Nanotechnology have advocated that nanotechnology should be specially regulated by governments for these reasons. Others counter that overregulation would stifle scientific research and the development of innovations which could greatly benefit mankind.
Longer-term concerns center on the implications that new technologies will have for society at large, and whether these could possibly lead to either a post scarcity economy, or alternatively exacerbate the wealth gap between developed and developing nations.
NANO TECHNOLOGY
It is a highly multidisciplinary field, drawing from fields such as applied physics, materials science, interface and colloid science, device physics, supramolecular chemistry (which refers to the area of chemistry that focuses on the noncovalent bonding interactions of molecules), self-replicating machines and robotics, chemical engineering, mechanical engineering, biological engineering, and electrical engineering. Much speculation exists as to what may result from these lines of research. Nanotechnology can be seen as an extension of existing sciences into the nanoscale, or as a recasting of existing sciences using a newer, more modern term.
Two main approaches are used in nanotechnology. In the "bottom-up" approach, materials and devices are built from molecular components which assemble themselves chemically by principles of molecular recognition. In the "top-down" approach, nano-objects are constructed from larger entities without atomic-level control. The impetus for nanotechnology comes from a renewed interest in Interface and Colloid Science, coupled with a new generation of analytical tools such as the atomic force microscope (AFM), and the scanning tunneling microscope (STM). Combined with refined processes such as electron beam lithography and molecular beam epitaxy, these instruments allow the deliberate manipulation of nanostructures, and led to the observation of novel phenomena.
Examples of nanotechnology in modern use are the manufacture of polymers based on molecular structure, and the design of computer chip layouts based on surface science. Despite the great promise of numerous nanotechnologies such as quantum dots and nanotubes, real commercial applications have mainly used the advantages of colloidal nanoparticles in bulk form, such as suntan lotion, cosmetics, protective coatings, drug delivery[1], and stain resistant clothing.
Wikibooks has a book on the topic of
Nanotechnology
One nanometer (nm) is one billionth, or 10-9 of a meter. For comparison, typical carbon-carbon bond lengths, or the spacing between these atoms in a molecule, are in the range .12-.15 nm, and a DNA double-helix has a diameter around 2 nm. On the other hand, the smallest cellular lifeforms, the bacteria of the genus Mycoplasma, are around 200 nm in length. To put that scale in to context the comparative size of a nanometer to a meter is the same as that of a marble to the size of the earth[3]. Or another way of putting it: a nanometer is the amount a man's beard grows in the time it takes him to raise the razor to his face[3].
Image of reconstruction on a clean Au(100) surface, as visualized using scanning tunneling microscopy. The individual atoms composing the surface are visible.
Main article: Nanomaterials
A number of physical phenomena become noticeably pronounced as the size of the system decreases. These include statistical mechanical effects, as well as quantum mechanical effects, for example the “quantum size effect” where the electronic properties of solids are altered with great reductions in particle size. This effect does not come into play by going from macro to micro dimensions. However, it becomes dominant when the nanometer size range is reached. Additionally, a number of physical (mechanical, electrical, optical, etc.) properties change when compared to macroscopic systems. One example is the increase in surface area to volume ratio altering mechanical, thermal and catalytic properties of materials. Novel mechanical properties of nanosystems are of interest in the nanomechanics research. The catalytic activity of nanomaterials also opens potential risks in their interaction with biomaterials.
Materials reduced to the nanoscale can suddenly show very different properties compared to what they exhibit on a macroscale, enabling unique applications. For instance, opaque substances become transparent (copper); inert materials become catalysts (platinum); stable materials turn combustible (aluminum); solids turn into liquids at room temperature (gold); insulators become conductors (silicon). A material such as gold, which is chemically inert at normal scales, can serve as a potent chemical catalyst at nanoscales. Much of the fascination with nanotechnology stems from these unique quantum and surface phenomena that matter exhibits at the nanoscale.
Main article: Molecular self-assembly
Modern synthetic chemistry has reached the point where it is possible to prepare small molecules to almost any structure. These methods are used today to produce a wide variety of useful chemicals such as pharmaceuticals or commercial polymers. This ability raises the question of extending this kind of control to the next-larger level, seeking methods to assemble these single molecules into supramolecular assemblies consisting of many molecules arranged in a well defined manner.
These approaches utilize the concepts of molecular self-assembly and/or supramolecular chemistry to automatically arrange themselves into some useful conformation through a bottom-up approach. The concept of molecular recognition is especially important: molecules can be designed so that a specific conformation or arrangement is favored due to non-covalent intermolecular forces. The Watson-Crick basepairing rules are a direct result of this, as is the specificity of an enzyme being targeted to a single substrate, or the specific folding of the protein itself. Thus, two or more components can be designed to be complementary and mutually attractive so that they make a more complex and useful whole.
Such bottom-up approaches should, broadly speaking, be able to produce devices in parallel and much cheaper than top-down methods, but could potentially be overwhelmed as the size and complexity of the desired assembly increases. Most useful structures require complex and thermodynamically unlikely arrangements of atoms. Nevertheless, there are many examples of self-assembly based on molecular recognition in biology, most notably Watson-Crick basepairing and enzyme-substrate interactions. The challenge for nanotechnology is whether these principles can be used to engineer novel constructs in addition to natural ones.
[edit] Molecular nanotechnology: a long-term view
Main article: Molecular nanotechnology
Molecular nanotechnology, sometimes called molecular manufacturing, is a term given to the concept of engineered nanosystems (nanoscale machines) operating on the molecular scale. It is especially associated with the concept of a molecular assembler, a machine that can produce a desired structure or device atom-by-atom using the principles of mechanosynthesis. Manufacturing in the context of productive nanosystems is not related to, and should be clearly distinguished from, the conventional technologies used to manufacture nanomaterials such as carbon nanotubes and nanoparticles.
When the term "nanotechnology" was independently coined and popularized by Eric Drexler (who at the time was unaware of an earlier usage by Norio Taniguchi) it referred to a future manufacturing technology based on molecular machine systems. The premise was that molecular-scale biological analogies of traditional machine components demonstrated molecular machines were possible: by the countless examples found in biology, it is known that sophisticated, stochastically optimised biological machines can be produced.
It is hoped that developments in nanotechnology will make possible their construction by some other means, perhaps using biomimetic principles. However, Drexler and other researchers[4] have proposed that advanced nanotechnology, although perhaps initially implemented by biomimetic means, ultimately could be based on mechanical engineering principles, namely, a manufacturing technology based on the mechanical functionality of these components (such as gears, bearings, motors, and structural members) that would enable programmable, positional assembly to atomic specification (PNAS-1981). The physics and engineering performance of exemplar designs were analyzed in Drexler's book Nanosystems.
But Drexler's analysis is very qualitative and does not address very pressing issues, such as the "fat fingers" and "Sticky fingers" problems. In general it is very difficult to assemble devices on the atomic scale, as all one has to position atoms are other atoms of comparable size and stickyness. Another view, put forth by Carlo Montemagno],[5] is that future nanosystems will be hybrids of silicon technology and biological molecular machines. Yet another view, put forward by the late Richard Smalley, is that mechanosynthesis is impossible due to the difficulties in mechanically manipulating individual molecules.
This led to an exchange of letters in the ACS publication Chemical & Engineering News in 2003.[6] Though biology clearly demonstrates that molecular machine systems are possible, non-biological molecular machines are today only in their infancy. Leaders in research on non-biological molecular machines are Dr. Alex Zettl and his colleagues at Lawrence Berkeley Laboratories and UC Berkeley. They have constructed at least three distinct molecular devices whose motion is controlled from the desktop with changing voltage: a nanotube nanomotor, a molecular actuator, and a nanoelectromechanical relaxation oscillator.
An experiment indicating that positional molecular assembly is possible was performed by Ho and Lee at Cornell University in 1999. They used a scanning tunneling microscope to move an individual carbon monoxide molecule (CO) to an individual iron atom (Fe) sitting on a flat silver crystal, and chemically bound the CO to the Fe by applying a voltage.
Space-filling model of the nanocar on a surface, using fullerenes as wheels.
Graphical representation of a rotaxane, useful as a molecular switch.
This device transfers energy from nano-thin layers of quantum wells to nanocrystals above them, causing the nanocrystals to emit visible light.[7]
[edit] Nanomaterials
This includes subfields which develop or study materials having unique properties arising from their nanoscale dimensions.[8]
Interface and Colloid Science has given rise to many materials which may be useful in nanotechnology, such as carbon nanotubes and other fullerenes, and various nanoparticles and nanorods.
Nanoscale materials can also be used for bulk applications; most present commercial applications of nanotechnology are of this flavor.
Progress has been made in using these materials for medical applications; see Nanomedicine.
[edit] Bottom-up approaches
These seek to arrange smaller components into more complex assemblies.
DNA nanotechnology utilizes the specificity of Watson-Crick basepairing to construct well-defined structures out of DNA and other nucleic acids.
Approaches from the field of "classical" chemical synthesis also aim at designing molecules with well-defined shape (e.g. bis-peptides[9]).
More generally, molecular self-assembly seeks to use concepts of supramolecular chemistry, and molecular recognition in particular, to cause single-molecule components to automatically arrange themselves into some useful conformation.
[edit] Top-down approaches
These seek to create smaller devices by using larger ones to direct their assembly.
Many technologies descended from conventional solid-state silicon methods for fabricating microprocessors are now capable of creating features smaller than 100 nm, falling under the definition of nanotechnology. Giant magnetoresistance-based hard drives already on the market fit this description,[10] as do atomic layer deposition (ALD) techniques. Peter Grünberg and Albert Fert received Nobel Prize in Physics for their discovery of Giant magnetoresistance and contributions to the field of spintronics in 2007.[11]
Solid-state techniques can also be used to create devices known as nanoelectromechanical systems or NEMS, which are related to microelectromechanical systems or MEMS.
Atomic force microscope tips can be used as a nanoscale "write head" to deposit a chemical upon a surface in a desired pattern in a process called dip pen nanolithography. This fits into the larger subfield of nanolithography.
[edit] Functional approaches
These seek to develop components of a desired functionality without regard to how they might be assembled.
Molecular electronics seeks to develop molecules with useful electronic properties. These could then be used as single-molecule components in a nanoelectronic device.[12] For an example see rotaxane.
Synthetic chemical methods can also be used to create synthetic molecular motors, such as in a so-called nanocar.
[edit] Speculative
These subfields seek to anticipate what inventions nanotechnology might yield, or attempt to propose an agenda along which inquiry might progress. These often take a big-picture view of nanotechnology, with more emphasis on its societal implications than the details of how such inventions could actually be created.
Molecular nanotechnology is a proposed approach which involves manipulating single molecules in finely controlled, deterministic ways. This is more theoretical than the other subfields and is beyond current capabilities.
Nanorobotics centers on self-sufficient machines of some functionality operating at the nanoscale. There are hopes for applying nanorobots in medicine[13][14][15], but it may not be easy to do such a thing because of several drawbacks of such devices.[16] Nevertheless, progress on innovative materials and methodologies has been demonstrated with some patents granted about new nanomanufacturing devices for future commercial applications, which also progressively helps in the development towards nanorobots with the use of embedded nanobioelectronics concept.[17][18]
Programmable matter based on artificial atoms seeks to design materials whose properties can be easily and reversibly externally controlled.
Due to the popularity and media exposure of the term nanotechnology, the words picotechnology and femtotechnology have been coined in analogy to it, although these are only used rarely and informally.
Damage to undersea cables
Tuesday night's earthquake off Taiwan disrupted Internet and telephone communications all over East Asia. While Taiwan and Singapore seem to be hardest hit by the damage to the cables, some foreign websites in China are still not loading properly.
India's Business Standard has some technical information about the damage to the communications cables:
An earthquake off Taiwan last night, measuring 6.7-7.1 on the Richter scale, knocked out Internet links to India for 20-25 minutes and affected Reliance Communications’ FLAG and VSNL’s SEA-ME-WE-3 under-sea cable systems, even as telecommunications around Asia was severely disrupted, with Internet services slowing and financial transactions being hindered, particularly in the currency market. However, BPO and IT services across India remained largely unaffected....The damage was contained to some extent since the disruption took place at a time when data and voice traffic had not peaked in Europe and the US, which accounted for a major part of their businesses. The other reason was that all Indian players had accounted for such natural disasters and built in two levels of redundancies.
These companies have coverage across the Pacific and the Atlantic and if one of these links snaps, the other one takes over seamlessly.
The FLAG cable links India, Thailand, Hong Kong, China, Korea and Japan. SEA-ME-WE 3 includes 39 landing points in 33 countries across four continents — from Western Europe to the Far East and Australia.
Other cables damaged in the quake included those of Asia-Pacific Cable Network, Asia Pacific Cable Network 2, Cable 2 Cable, China US Cable Network, and East Asia Cable.
A VSNL spokesperson said: “VSNL’s traffic has not been significantly affected by the earthquake in Taiwan since we do not have cable systems going there directly. SEA-ME-WE 3 interconnects with other cable systems in the region that has been affected, and hence the disruption. The company is taking action to re-route its affected traffic to other cable systems and normalcy is expected in about 24 hours.”... ...South Korea’s top fixed-line and broadband service provider, KT Corp, said six submarine cables were knocked out by Tuesday night’s earthquakes. “Twenty-seven of our customers were hit, including banks and churches,” a KT spokesperson said. “It is not known yet when we can fully restore services.”... ...Global information company Reuters Group said users of its services in Japan, South Korea and Taiwan had been affected, although dealing services were restored in Tokyo in the afternoon. The main quake, measured by Taiwan’s Central Weather Bureau at magnitude 6.7 and at magnitude 7.1 by the US Geological Survey, struck off Taiwan’s southern coast on Tuesday. Two people were killed. In China, financial markets worked normally, but China Telecommunications Group, the country’s biggest fixed-line telephone operator and parent of China Telecom Corp, said Internet had been badly disrupted. ...Chunghwa Telecom, Taiwan’s biggest telecom carrier, said two of the four major under-sea cables out of Taiwan had been affected, initially cutting more than half of its international telecommunications capacity. Calls to Southeast Asia were the worst affected, with less than 10 per cent going through — an improvement since the morning, when less than 2 per cent succeeded. KDDI Corp, Japan’s second-largest telecom company, said communication along submarine cables out of Japan went through Taiwan before reaching Southeast Asian countries, which was leading to disruption, but there were alternative lines. PCCW, Hong Kong’s main fixed-line telecom provider, said several under-sea cables it part-owned had been damaged. “Data transfer is down by half,” a spokesperson said. Both Singapore Telecommunications (SingTel), Southeast Asia’s top phone company, and local rival StarHub Ltd said Internet services were slow. But SingTel said traffic was being diverted and repair work was in progress, adding, “Our submarine cables linking to Europe and the US have not been affected.” Philippine Long Distance Telephone Co said its Internet service was intermittent and international phone calls had been disrupted but domestic calls and its Smart mobile phone service were working normally.
Robotics
Robotics is the science and technology of robots, their design, manufacture, and application.[1] Robotics requires a working knowledge of electronics, mechanics and software, and is usually accompanied by a large working knowledge of many subjects.[2] A person working in the field is a roboticist.
Although the appearance and capabilities of robots vary vastly, all robots share the features of a mechanical, movable structure under some form of autonomous control. The structure of a robot is usually mostly mechanical and can be called a kinematic chain (its functionality being akin to the skeleton of the human body). The chain is formed of links (its bones), actuators (its muscles) and joints which can allow one or more degrees of freedom. Most contemporary robots use open serial chains in which each link connects the one before to the one after it. These robots are called serial robots and often resemble the human arm. Some robots, such as the Stewart platform, use closed parallel kinematic chains. Other structures, such as those that mimic the mechanical structure of humans, various animals and insects, are comparatively rare. However, the development and use of such structures in robots is an active area of research (e.g. biomechanics). Robots used as manipulators have an end effector mounted on the last link. This end effector can be anything from a welding device to a mechanical hand used to manipulate the environment.
Etymology:
The word robotics was first used in print by Isaac Asimov, in his science fiction short story "Runaround", published in March 1942 in Astounding Science Fiction. While it was based on the word "robot" coined by science fiction author Karel Čapek, Asimov was unaware that he was coining a new term. The design of electrical devices is called electronics, so the design of robots is called robotics.[3] Before the coining of the term, however, there was interest in ideas similar to robotics (namely automata and androids) dating as far back as the 8th or 7th century BC. In the Iliad, the god Hephaestus made talking handmaidens out of gold.[4] Archytas of Tarentum is credited with creating a mechanical Pigeon in 400 BC.[5] Robots are used in industrial, military, exploration, home making, and academic and research applications.
Components of robots
[edit] Actuation
A robot leg, powered by Air Muscles.
The actuators are the 'muscles' of a robot; the parts which convert stored energy into movement. By far the most popular actuators are electric motors, but there are many others, some of which are powered by electricity, while others use chemicals, or compressed air.
Motors: By far the vast majority of robots use electric motors, of which there are several kinds. DC motors, which are familiar to many people, spin rapidly when an electric current is passed through them. They will spin backwards if the current is made to flow in the other direction.
Stepper Motors: As the name suggests, stepper motors do not spin freely like DC motors, they rotate in steps of a few degrees at a time, under the command of a controller. This makes them easier to control, as the controller knows exactly how far they have rotated, without having to use a sensor. Therefore they are used on many robots and CNC machining centres.
Piezo Motors: A recent alternative to DC motors are piezo motors, also known as ultrasonic motors. These work on a fundamentally different principle, whereby tiny piezoceramic legs, vibrating many thousands of times per second, walk the motor round in a circle or a straight line.[7] The advantages of these motors are incredible nanometre resolution, speed and available force for their size.[8] These motors are already available commercially, and being used on some robots.[9][10]
Air Muscles: The air muscle is a simple yet powerful device for providing a pulling force. When inflated with compressed air, it contracts by up to 40% of its original length. The key to its behaviour is the braiding visible around the outside, which forces the muscle to be either long and thin, or short and fat. Since it behaves in a very similar way to a biological muscle, it can be used to construct robots with a similar muscle/skeleton system to an animal.[11] For example, the Shadow robot hand uses 40 air muscles to power its 24 joints.
Electroactive Polymers: These are a class of plastics which change shape in response to electrical stimulation.[12] They can be designed so that they bend, stretch or contract, but so far there are no EAPs suitable for commercial robots, as they tend to have low efficiency or are not robust.[13] Indeed, all of the entrants in a recent competition to build EAP powered arm wrestling robots, were beaten by a 17 year old girl.[14] However, they are expected to improve in the future, where they may be useful for microrobotic applications.[15]
Elastic nanotubes are a promising, early-stage experimental technology. The absence of defects in nanotubes enables these filaments to deform elastically by several percent, with energy storage levels of perhaps 10J per cu. cm for metal nanotubes. Human biceps could be replaced with an 8mm diameter wire of this material. Such compact "muscle" might allow future robots to outrun and outjump humans.
Manipulation
Robots which must work in the real world require some way to manipulate objects; pick up, modify, destroy or otherwise have an effect. Thus the 'hands' of a robot are often referred to as end effectors[17], while the arm is referred to as a manipulator.[18] Most robot arms have replacable effectors, each allowing them to perform some small range of tasks. Some have a fixed manipulator which cannot be replaced, while a few have one very general purpose manipulator, for example a humanoid hand.
A simple gripper
Grippers: A common effector is the gripper. In its simplest manifestation it consists of just two fingers which can open and close to pick up and let go of a range of small objects. See End effectors [1].
Vacuum Grippers: Pick and place robots for electronic components and for large objects like car windscreens, will often use very simple vacuum grippers. These are very simple astrictive devices, but can hold very large loads provided the prehension surface is smooth enough to ensure suction.
General purpose effectors: Some advanced robots are beginning to use fully humanoid hands, like the Shadow Hand (right), or the Schunk hand.[19] These highly dexterous manipulators, with as many as 20 degrees of freedom and hundreds of tactile sensors[20] can be difficult to control. The computer must consider a great deal of information, and decide on the best way to manipulate an object from many possibilities.
For the definitive guide to all forms of robot endeffectors, their design and usage consult the book "Robot Grippers" [21].
Locomotion
[edit] Rolling Robots
Segway in the Robot museum in Nagoya.
For simplicity, most mobile robots have four wheels. However, some researchers have tried to create more complex wheeled robots, with only one or two wheels.
Two-wheeled balancing: While the Segway is not commonly thought of as a robot, it can be thought of as a component of a robot. Several real robots do use a similar dynamic balancing algorithm, and NASA's Robonaut has been mounted on a Segway.[22]
Ballbot: Carnegie Mellon University researchers have developed a new type of mobile robot that balances on a ball instead of legs or wheels. "Ballbot" is a self-contained, battery-operated, omnidirectional robot that balances dynamically on a single urethane-coated metal sphere. It weighs 95 pounds and is the approximate height and width of a person. Because of its long, thin shape and ability to maneuver in tight spaces, it has the potential to function better than current robots can in environments with people.[23]
Track Robot: Another type of rolling robot is one that has tracks, like NASA's Urban Robot, Urbie. [24]
[edit] Walking Robots
iCub robot, designed by the RobotCub Consortium
Walking is a difficult and dynamic problem to solve. Several robots have been made which can walk reliably on two legs, however none have yet been made which are as robust as a human. Typically, these robots can walk well on flat floors, and can occasionally walk up stairs. None can walk over rocky, uneven terrain. Some of the methods which have been tried are:
Zero Moment Point (ZMP) Technique: is the algorithm used by robots such as Honda's ASIMO. The robot's onboard computer tries to the keep the total inertial forces (the combination of earth's gravity and the acceleration and deceleration of walking), exactly opposed by the floor reaction force (the force of the floor pushing back on the robot's foot). In this way, the two forces cancel out, leaving no moment (force causing the robot to rotate and fall over).[25] However, this is not exactly how a human walks, and the difference is quite apparent to human observers, some of whom have pointed out that ASIMO walks as if it needs the lavatory.[26][27][28] ASIMO's walking algorithm is not static, and some dynamic balancing is used (See below). However, it still requires a smooth surface to walk on.
Hopping: Several robots, built in the 1980s by Marc Raibert at the MIT Leg Laboratory, successfully demonstrated very dynamic walking. Initially, a robot with only one leg, and a very small foot, could stay upright simply by hopping. The movement is the same as that of a person on a pogo stick. As the robot falls to one side, it would jump slightly in that direction, in order to catch itself.[29] Soon, the algorithm was generalised to two and four legs. A bipedal robot was demonstrated running and even performing somersaults.[30] A quadruped was also demonstrated which could trot, run, pace and bound.[31] For a full list of these robots, see the MIT Leg Lab Robots page.
Dynamic Balancing: A more advanced way for a robot to walk is by using a dynamic balancing algorithm, which is potentially more robust than the Zero Moment Point technique, as it constantly monitors the robot's motion, and places the feet in order to main stability.[32] This technique was recently demonstrated by Anybots' Dexter Robot,[33] which is so stable, it can even jump.[34]
Passive Dynamics: Perhaps the most promising approach being taken is to use the momentum of swinging limbs for greater efficiency. It has been shown that totally unpowered humanoid mechanisms can walk down a gentle slope, using only gravity to propel themselves. Using this technique, a robot need only supply a small amount of motor power to walk along a flat surface or a little more to walk up a hill. This technique promises to make walking robots at least ten times more efficient than ZMP walkers, like ASIMO.[35][36]
Other methods of locomotion
RQ-4 Global Hawk Unmanned Aerial Vehicle. No pilot means no windows.
Flying: A modern passenger airliner is essentially a flying robot, with two humans to attend it. The autopilot can control the plane for each stage of the journey, including takeoff, normal flight and even landing.[citation needed] Other flying robots are completely automated, and are known as Unmanned Aerial Vehicles (UAVs). They can be smaller and lighter without a human pilot, and fly into dangerous territory for military surveillance missions. Some can even fire on targets under command. UAVs are also being developed which can fire on targets automatically, without the need for a command from a human. Other flying robots include cruise missiles, the Entomopter and the Epson micro helicopter robot.
Two robot snakes. Left one has 32 motors, the right one 10.
Snake: Several snake robots have been successfully developed. Mimicking the way real snakes move, these robots can navigate very confined spaces, meaning they may one day be used to search for people trapped in collapsed buildings.[37] The Japanese ACM-R5 snake robot [38] can even navigate both on land and in water.[39]
Skating: A small number of skating robots have been developed, one of which is a multi-mode walking and skating device, Titan VIII. It has four legs, with unpowered wheels, which can either step or roll[40]. Another robot, Plen, can use a miniature skateboard or rollerskates, and skate across a desktop.[41]
Swimming: It is calculated that some fish can achieve a propulsive efficiency greater than 90%. [42] Furthermore, they can accelerate and manoeuver far better than any man-made boat or submarine, and produce less noise and water disturbance. Therefore, many researchers studying underwater robots would like to copy this type of locomotion.[43] Notable examples are the Essex University Computer Science Robotic Fish[44], and the Robot Tuna built by the Institute of Field Robotics, to analyse and mathematically model thunniform motion.[45]
Human interaction
Kismet (robot) can produce a range of facial expressions
If robots are to work effectively in homes and other non-industrial environments, the way they are instructed to perform their jobs, and especially how they will be told to stop will be of critical importance. The people who interact with them may have little or no training in robotics, and so any interface will need to be extremely intuitive. Science fiction authors also typically assume that robots will eventually communicate with humans by talking, gestures and facial expressions, rather than a command-line interface. Although speech would be the most natural way for the human to communicate, it is quite unnatural for the robot. It will be quite a while before robots interact as naturally as the fictional C3P0.
Speech Recognition: Interpreting the continuous flow of sounds coming from a human, in real time, is a difficult task for a computer, mostly because of the great variability of speech. The same word, spoken by the same person may sound different depending on local acoustics, volume, the previous word, whether or not the speaker has a cold, etc.. It becomes even harder when the speaker has a different accent.[46] Nevertheless, great strides have been made in the field since Davis, Biddulph, and Balashek designed the first "voice input system" which recognized "ten digits spoken by a single user with 100% accuracy" in 1952.[47] Currently, the best systems can recognise continuous, natural speech, up to 160 words per minute, with an accuracy of 95%.[48]
Gestures: One can imagine, in the future, explaining to a robot chef how to make a pastry, or asking directions from a robot police officer. On both of these occasions, making hand gestures would aid the verbal descriptions. In the first case, the robot would be recognising gestures made by the human, and perhaps repeating them for confirmation. In the second case, the robot police officer would gesture to indicate "down the road, then turn right". It is quite likely that gestures will make up a part of the interaction between humans and robots.[49] A great many systems have been developed to recognise human hand gestures.[50]
Facial expression: Facial expressions can provide rapid feedback on the progress of a dialog between two humans, and soon it may be able to do the same for humans and robots. A robot should know how to approach a human, judging by their facial expression and body language. Whether the person is happy, frightened or crazy-looking affects the type of interaction expected of the robot. Likewise, a robot like Kismet can produce a range of facial expressions, allowing it to have meaningful social exchanges with humans.[51]
Personality: Many of the robots of science fiction have personality, and that is something which may or may not be desirable in the commercial robots of the future.[52] Nevertheless, researchers are trying to create robots which appear to have a personality[53][54]: i.e. they use sounds, facial expressions and body language to try to convey an internal state, which may be joy, sadness or fear. One commercial example is Pleo, a toy robot dinosaur, which can exhibit several apparent emotions.[55]
Control
The mechanical structure of a robot must be controlled to perform tasks. The control of a robot involves three distinct phases - perception, processing and action (robotic paradigms). Sensors give information about the environment or the robot itself (e.g. the position of its joints or its end effector). Using strategies from the field of control theory, this information is processed to calculate the appropriate signals to the actuators (motors) which move the mechanical structure. The control of a robot involves path planning, pattern recognition, obstacle avoidance, etc. More complex and adaptable control strategies can be referred to as artificial intelligence.
Dynamics and kinematics
The study of motion can be divided into kinematics and dynamics. Direct kinematics refers to the calculation of end effector position, orientation, velocity and acceleration when the corresponding joint values are known. Inverse kinematics refers to the opposite case in which required joint values are calculated for given end effector values, as done in path planning. Some special aspects of kinematics include handling of redundancy (different possibilities of performing the same movement), collision avoidance and singularity avoidance. Once all relevant positions, velocities and accelerations have been calculated using kinematics, methods from the field of dynamics are used to study the effect of forces upon these movements. Direct dynamics refers to the calculation of accelerations in the robot once the applied forces are known. Direct dynamics is used in computer simulations of the robot. Inverse dynamics refers to the calculation of the actuator forces necessary to create a prescribed end effector acceleration. This information can be used to improve the control algorithms of a robot.
In each area mentioned above, researchers strive to develop new concepts and strategies, improve existing ones and improve the interaction between these areas. To do this, criteria for "optimal" performance and ways to optimize design, structure and control of robots must be developed and implemented.
Mechatronics Engineering
Mechatronics is the combination of mechanical engineering, electronic engineering and software engineering. The purpose of this interdisciplinary engineering field is the study of automata from an engineering perspective and serves the purposes of controlling advanced hybrid systems. The word itself is a portmanteau of 'Mechanics' and 'Electronics'.
Description
Aerial Venn diagram from RPI's website describes the various fields that make up Mechatronics
Mechatronics is centred on mechanics, electronics, control engineering, computing, molecular engineering (from nanochemistry and biology) which, combined, make possible the generation of simpler, more economical, reliable and versatile systems. The portmanteau "Mechatronics" was first coined by Mr. Tetsuro Mori, a senior engineer of the Japanese company Yaskawa, in 1969. Mechatronics may alternatively be referred to as "electromechanical systems" or less often as "control and automation engineering".
Engineering cybernetics deals with the question of control engineering of mechatronic systems. It is used to control or regulate such a system (see control theory). Through collaboration the mechatronic modules perform the production goals and inherit flexible and agile manufacturing properties in the production scheme. Modern production equipment consists of mechatronic modules that are integrated according to a control architecture. The most known architectures involve hierarchy, polyarchy, heterarchy and hybrid. The methods for achieving a technical effect are described by control algorithms, which may or may not utilize formal methods in their design. Hybrid-systems important to Mechatronics include production systems, synergy drives, planetary exploration rovers, automotive subsystems such as anti-lock braking systems, spin-assist and every day equipment such as autofocus cameras, video, hard disks, CD-players, washing machines.
A typical mechatronic engineering degree would involve classes in engineering mathematics, mechanics, machine component design, mechanical design, thermodynamics, circuits and systems, electronics and communications, control theory, programming, digital signal processing, power engineering, robotics and usually a final year thesis.
Variant of the field
An emerging variant of this field is biomechatronics, whose purpose is to integrate machine and man, usually in the form of removable gadgets such as exoskeleton. This is the “real-life” version of cyberware.
