It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Friday, October 29, 2021
Amount of information in visible universe quantified
Estimate measures information encoded in particles, opens door to practical experiments
WASHINGTON, October 19, 2021 -- Researchers have long suspected a connection between information and the physical universe, with various paradoxes and thought experiments used to explore how or why information could be encoded in physical matter. The digital age propelled this field of study, suggesting that solving these research questions could have tangible applications across multiple branches of physics and computing.
In AIP Advances, from AIP Publishing, a University of Portsmouth researcher attempts to shed light on exactly how much of this information is out there and presents a numerical estimate for the amount of encoded information in all the visible matter in the universe -- approximately 6 times 10 to the power of 80 bits of information. While not the first estimate of its kind, this study's approach relies on information theory.
"The information capacity of the universe has been a topic of debate for over half a century," said author Melvin M. Vopson. "There have been various attempts to estimate the information content of the universe, but in this paper, I describe a unique approach that additionally postulates how much information could be compressed into a single elementary particle."
To produce the estimate, the author used Shannon's information theory to quantify the amount of information encoded in each elementary particle in the observable universe as 1.509 bits of information. Mathematician Claude Shannon, called the Father of the Digital Age because of his work in information theory, defined this method for quantifying information in 1948.
"It is the first time this approach has been taken in measuring the information content of the universe, and it provides a clear numerical prediction," said Vopson. "Even if not entirely accurate, the numerical prediction offers a potential avenue toward experimental testing."
Recent research sheds light on the ways information and physics interact, such as how information exits a black hole. However, the precise physical significance of information remains elusive, but multiple radical theories contend information is physical and can be measured.
In previous studies, Vopson postulated information is a fifth state of matter alongside solid, liquid, gas, and plasma, and that elusive dark matter could be information. Vopson's study also included derivation of a formula that reproduces accurately the well-known Eddington number, the total number of protons in the observable universe.
While the approach in this study ignored antiparticles and neutrinos and made certain assumptions about information transfer and storage, it offers a unique tool for estimating the information content per elementary particle. Practical experiments can now be used to test and refine these predictions, including research to prove or disprove the hypothesis that information is the fifth state of matter in the universe.
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The article "Estimation of the information contained in the visible matter of the universe" is authored by Melvin M. Vopson. The article will appear in AIP Advances on Oct. 19, 2021 (DOI: 10.1063/5.0064475). After that date, it can be accessed at https://aip.scitation.org/doi/full/10.1063/5.0064475.
ABOUT THE JOURNAL
AIP Advances is an open access journal publishing in all areas of physical sciences—applied, theoretical, and experimental. The inclusive scope of AIP Advances makes it an essential outlet for scientists across the physical sciences. See https://aip.scitation.org/journal/adv.
Very young children learn words at a tremendous rate. Now researchers at the Center for Mind and Brain at the University of California, Davis, have for the first time seen how specific brain regions activate as two-year-olds remember newly learned words — while the children were sleeping. The work is published Oct. 19 in Current Biology.
“We can now leverage sleep to look at basic mechanisms of learning new words,” said Simona Ghetti, professor at the Center for Mind and Brain and UC Davis Department of Psychology.
At two to three years old, children enter a unique age in memory development, Ghetti said. But young children are challenging to study, and they especially dislike being in a functional MRI scanner.
“The scariest things to small children are darkness and loud noises, and that’s what it’s like during an MRI scan,” Ghetti said.
Ghetti’s team had previously found that if children fell asleep in a scanner while it wasn’t working, they could later start the scan and see brain activation in response to songs the children had heard earlier.
In the new study, they looked at how toddlers retained memories of words.
Graduate student Elliott Johnson and Ghetti created a series of made-up, but realistic sounding words as names for a series of objects and puppets. In the first session, two-year-olds were introduced to two objects and two puppets, then tested on their memory of the names after a few minutes. A week later, they returned and were tested on whether they remembered the names of the objects and puppets. Soon after the second test, they slept overnight in an MRI scanner. The researchers played back the words the children had learned, as well as other words, as they slept.
Activation of the hippocampus in learning
The researchers found activation of the hippocampus and the anterior medial temporal lobe when the sleeping children were played words they had previously learned. This activation correlated with how well they had performed when they initially learned the words a week earlier.
“This suggests that the hippocampus is particularly important for laying down the initial memory for words,” Ghetti said. “This compares quite well with findings from older children and adults, where the hippocampus is associated with learning and with recalling recent memories” Johnson added.
Although young children are rapidly forming memories of new words, they are also losing a lot of memories. When we form a memory, it includes the context: where, when, what else was going on. But if we just learned the name of an object, we don’t need to remember the context to use the word again. That extra detail can go.
It’s not clear how children remember some things, such as names, while losing the rest. Ghetti suspects that overlapping learning experiences interfere with each other and cancel out the unneeded details. Future research will focus on the memory processes that support these changes.
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Additional authors on the paper are: graduate student Lindsey Mooney, Center for Mind and Brain; Katharine Graf Estes, associate professor at the Center for Mind and Brain and Department of Psychology; and Christine Nordahl, Department of Psychiatry and Behavioral Sciences and MIND Institute. The work was funded by the NIH.
Oct. 29 (UPI) -- Dogs interpret words from speech using computations and brain regions similar to human infants, a study published Friday by Current Biology found.
Based on measurements of electrical activity and changes in blood flow in the brain, dogs appear to be able to track words and syllables spoken by humans the same way humans do, the researchers said.
Electroencephalograms, which measure electrical activity in the brain, and functional magnetic resonance imaging, or fMRI, scans, which detect changes in blood flow in the brain, performed on dogs suggests that the animals use similar brain regions to interpret speech.
"We know that in humans both general learning-related and language-related brain regions participate in this process -- and we found the same duality in dogs," study co-author Marianna Boros said in a press release.
"Both a generalist and a specialist brain region seemed to be involved in statistical learning from speech, but the activation patterns were different in the two," said Boros, a postdoctoral researcher at Eötvös Loránd University in Hungary.
In dogs, the "generalist" brain region -- the basal ganglia -- responded more to a random speech stream, where no specific words could be detected using syllables, than to a structured speech stream in which words were easy to spot just by computing syllables.
Meanwhile, in dogs, the specialist brain region -- the auditory cortex -- responded more to the structured speech stream.
In humans, the auditory cortex plays a key role in statistical learning from speech, Boros said.
"We believe that this activity increase is the trace word learning leaves on the auditory cortex" in dogs, she said.
A study published in August by Scientific Reports suggested that dogs process speech hierarchically, just like humans, meaning they process intonations first, at lower stages, and word meanings at higher stages.
Similarly, human infants can spot new words in a speech stream before they learn what those words mean, according to the researchers.
To learn new words from continuous speech, infants must not only count how often certain syllables occur together, they need to also calculate how likely it is that these syllables occur together.
To tell where a word ends and another one begins, they make complex calculations to keep track of syllable patterns, in essence learning that syllables that usually appear together are probably words, and those that do not probably are not words.
This is how infants solve the seemingly difficult task of word segmentation -- "they calculate complex statistics about the probability of one syllable following the other," Boros said.
The new findings suggest dogs may also recognize such complex regularities in speech, according to the researchers.
For this study, Boros and her colleagues measured their electrical brain activity using electroencephalogram, or EEG, readings, as well as fMRI scans, which revealed the brain regions responsible for the complex computational capacity in dogs.
The tests were performed on awake, cooperating, unrestrained animals previously trained to lay motionless during the time of the measurements, the researchers said.
The researchers observed differences in dogs' brain waves with frequent versus rare words, as well as brain wave differences for syllables that frequently occur together compared with syllables that only occasionally do.
This indicates dogs keep track not only of simple statistics, or the number of times a word occurs, but also of complex statistics, or the probability that a word's syllables occur together, which has never been seen in other non-human mammals, according to the researchers.
However, how these human-analogue brain mechanisms for word learning emerged in dogs remains unknown, the researchers said.
"Until now we did not know if any other mammal can also use such complex computations to extract words from speech," Boros said.
"Dogs are the earliest domesticated animal species and probably the one we speak most often to, [but] we know very little about the neural processes underlying their word learning capacities," she said.
The surprising marine biodiversity in the Barcelona Forum beach
A study identified 514 marine species in the bathing areas of the Barcelona Forum, an artificial beach affected by different anthropogenic impacts. This high biodiversity –which includes the presence of exotic species– is a shocking finding in such an altered marine habitat like this city beach in Barcelona (Catalonia, Spain).
The authors of the study are the experts Manuel Ballesteros and Àlex Parera, from the Faculty of Biology of the University of Barcelona (UB), together with Miquel Pontes, from the Marine Life Study Group (VIMAR); Xavier Salvador, from the Institute of Marine Sciences (ICM-CSIC), and Guillermo Álvarez, from the Catalan Federation of Underwater Activities (FECDAS). The paper was published in Monografies de la Institució Catalana d’Història Natural –a subsidiary of the Institute for Catalan Studies–, whose editor in chief is Professor Juli Pujade-Villar, from the Faculty of Biology of the UB.
Citizen science to uncover the hidden marine biodiversity
The beach in Forum, located between the mouth of the Besòs River and the harbour of the Forum, is a small area, which is enclosed but connected to the open sea. A large part of the studied area is for nautical sports activities –it features a number of small recreational boats– and for bathing.
From 2017 to 2019, after more than 250 hours of diving, UB-IRBio experts and teams of citizen science volunteer collaborators from FECDAS and VIMAR analysed the marine life of the Fòrum beach. Molluscs, fish, crustaceans, and algae are the most abundant groups identified in the study, according to the subsequent analysis of photographs and specimens examined in the laboratory.
The marine habitat of this artificial environment is quite stable "and that could be one of the factors that explain this great biodiversity", says lecturer Manuel Ballesteros, from the Department of Evolutionary Biology, Ecology and Environmental Sciences at the University of Barcelona. "The high specific diversity found in the bathing area –514 marine species– is surprising, since it is an area that is quite polluted anthropically, with remains from the construction of the pier itself, effluents from the Fòrum wastewater treatment plant and other waste (towelettes, pieces of metal plate, plastic containers, beverage cans, etc.)".
Apart from the exotic species, the organisms that have benefited most from the urban transformation of the Fòrum line are algae, sponges, bryozoans and colonial tunicates and fish typical of rocky substrates, i.e. benthic species that settle on a hard substrate.
Some species of algae and benthic invertebrates are able to settle on the surface of the vertical walls of the urban beach –and also on the stairs at the bottom of the bathing area and on the concrete base of the piles.
"The stones that are in the shallows create a good habitat for infralapidicolar invertebrate species, both mobile and sedentary. At the muddy bottom, beyond the central pylons, species capable of burying themselves find their ideal habitat. It is also a good spawning ground for cuttlefish and sea hares, and some fish species find shelter there during their juvenile phase", explains Àlex Parera, an expert from the Department of Evolutionary Biology, Ecology and Environmental Sciences at the University of Barcelona.
CAPTION
The exotic polychaete 'Branchiomma luctuosum'.
CREDIT
Manuel Ballesteros (UB)
Exotic species in an artificial environment
The findings of fifteen exotic marine species in the Forum beach confirms the hypothesis of the tropicalization phenomenon that is taking place in some areas of the Mediterranean according to some research studies. “With the water temperature risings, especially in the interior of harbours and marinas, these coastal habitats are more and more favourable to the settlement of species from warmer waters”, notes the expert Miquel Pontes (VIMAR).
Regarding the sea hare Bursatella leachii, an invertebrate that appears only in the beach in Forum sporadically, everything suggests that it does not have a negative impact on other marine species. Since it eats diatoms, this mollusc does not compete with other native species of sea hares, which are macroherbivorous.
"However, the polychaete Branchiomma luctuosum is a more abundant exotic species than Bursatella leachii and it is present on this beach almost all year round. Therefore, it could compete against other filter-feeding and suspension-feeding species", says Xavier Salvador (ICM-CSIC).
Goodbye to the fan mussel in the Forum city beach
According to the study, the fan mussel (Pinna nobilis) –the largest bivalve mollusc endemic to the Mediterranean– has disappeared from this urban beach. In 2018, at a depth of two metres in the bathing area, four live specimens could be counted, apart from some empty shells of the same species.
“Unfortunately, in previous dives, it was found that all specimens were dead, many probably due to the infection caused by the protozoan Haplosporidium pinnae, which has decimated the populations of fan mussels in almost the whole Mediterranean”, says Guillermo Álvarez (FECDAS).
Waste and marine biodiversity
The deterioration of the quality of water –especially due to inputs from the Besòs river and effluents from the Fòrum wastewater treatment plant– is one of the main factors that endanger the conservation of marine species populations along the urban coastline. The behaviour of some bathers or visitors does not help, since many throw rubbish on the urban beach and threaten marine biodiversity.
"Algae and invertebrate species have been found living on or under metal plates, or empty cans", authors say. "It seems a contradiction, but despite the deplorable appearance of some areas due to the accumulation of marine litter, some species can take advantage of the substrate created by these materials”.
"In the future, it would be important to promote regular cleanings of the urban beach, promote environmental education for visitors –with a special emphasis on school groups and young students–, ban people from throwing objects into the water and place ecological containers as priority actions to preserve the ecological values of the marine environment in the bathing area of the Barcelona Forum", the authors conclude.
An MIT study suggests our brains are not optimized to calculate the shortest possible route when navigating on foot. In this figure, pedestrian paths are shown in red while the shortest path is in blue. Credit: MIT
Everyone knows the shortest distance between two points is a straight line. However, when you're walking along city streets, a straight line may not be possible. How do you decide which way to go?
A new MIT study suggests that our brains are actually not optimized to calculate the so-called "shortest path" when navigating on foot. Based on a dataset of more than 14,000 people going about their daily lives, the MIT team found that instead, pedestrians appear to choose paths that seem to point most directly toward their destination, even if those routes end up being longer. They call this the "pointiest path."
This strategy, known as vector-based navigation, has also been seen in studies of animals, from insects to primates. The MIT team suggests vector-based navigation, which requires less brainpower than actually calculating the shortest route, may have evolved to let the brain devote more power to other tasks.
"There appears to be a tradeoff that allows computational power in our brain to be used for other things—30,000 years ago, to avoid a lion, or now, to avoid a perilious SUV," says Carlo Ratti, a professor of urban technologies in MIT's Department of Urban Studies and Planning and director of the Senseable City Laboratory. "Vector-based navigation does not produce the shortest path, but it's close enough to the shortest path, and it's very simple to compute it."
Ratti is the senior author of the study, which appears today in Nature Computational Science. Christian Bongiorno, an associate professor at Université Paris-Saclay and a member of MIT's Senseable City Laboratory, is the study's lead author. Joshua Tenenbaum, a professor of computational cognitive science at MIT and a member of the Center for Brains, Minds, and Machines and the Computer Science and Artificial Intelligence Laboratory (CSAIL), is also an author of the paper. A preprint version of this study was posted to arXiv.org earlier this year.
Vector-based navigation
Twenty years ago, while a graduate student at Cambridge University, Ratti walked the route between his residential college and his departmental office nearly every day. One day, he realized that he was actually taking two different routes—one on to the way to the office and a slightly different one on the way back.
"Surely one route was more efficient than the other, but I had drifted into adapting two, one for each direction," Ratti says. "I was consistently inconsistent, a small but frustrating realization for a student devoting his life to rational thinking."
At the Senseable City Laboratory, one of Ratti's research interests is using large datasets from mobile devices to study how people behave in urban environments. Several years ago, the lab acquired a dataset of anonymized GPS signals from cell phones of pedestrians as they walked through Boston and Cambridge, Massachusetts, over a period of one year. Ratti thought that these data, which included more than 550,000 paths taken by more than 14,000 people, could help to answer the question of how people choose their routes when navigating a city on foot.
The research team's analysis of the data showed that instead of choosing the shortest routes, pedestrians chose routes that were slightly longer but minimized their angular deviation from the destination. That is, they choose paths that allow them to more directly face their endpoint as they start the route, even if a path that began by heading more to the left or right might actually end up being shorter.
"Instead of calculating minimal distances, we found that the most predictive model was not one that found the shortest path, but instead one that tried to minimize angular displacement—pointing directly toward the destination as much as possible, even if traveling at larger angles would actually be more efficient," says Paolo Santi, a principal research scientist in the Senseable City Lab and at the Italian National Research Council, and a corresponding author of the paper. "We have proposed to call this the pointiest path."
This was true for pedestrians in Boston and Cambridge, which have a convoluted network of streets, and in San Francisco, which has a grid-style street layout. In both cities, the researchers also observed that people tended to choose different routes when making a round trip between two destinations, just as Ratti did back in his graduate school days.
"When we make decisions based on angle to destination, the street network will lead you to an asymmetrical path," Ratti says. "Based on thousands of walkers, it is very clear that I am not the only one: Human beings are not optimal navigators."
Moving around in the world
Studies of animal behavior and brain activity, particularly in the hippocampus, have also suggested that the brain's navigation strategies are based on calculating vectors. This type of navigation is very different from the computer algorithms used by your smartphone or GPS device, which can calculate the shortest route between any two points nearly flawlessly, based on the maps stored in their memory.
Without access to those kinds of maps, the animal brain has had to come up with alternative strategies to navigate between locations, Tenenbaum says.
"You can't have a detailed, distance-based map downloaded into the brain, so how else are you going to do it? The more natural thing might be use information that's more available to us from our experience," he says. "Thinking in terms of points of reference, landmarks, and angles is a very natural way to build algorithms for mapping and navigating space based on what you learn from your own experience moving around in the world."
"As smartphone and portable electronics increasingly couple human and artificial intelligence, it is becoming increasingly important to better understand the computational mechanisms used by our brain and how they relate to those used by machines," Ratti says.Communicating vehicles could ease through intersections more efficiently
Researchers suggest electric vehicles need to be made lighter
Credit: Pixabay/CC0 Public Domain
A pair of economists, one with the University of Calgary, the other, the University of California, along with a civil engineer from Carnegie Mellon University, is suggesting in a Comment piece in the journal Nature, that electric vehicles (EVs) need to be lighter if they are to replace gasoline-powered vehicles. In their paper, Blake Shaffer, Maximilian Auffhammer and Constantine Samaras suggest that the added weight of EVs makes them less safe and less efficient and therefore less economical.
In their paper, the authors note that climate change has put EVs on a path to replace cars powered by gasoline. But they also note that for the changeover to be successful EVs need to be made much lighter.
EVs are heavier than gasoline-powered vehicles because of their heavy battery packs. They are also heavier because engineers have to add strength to the vehicles to allow them to carry such heavy batteries. Therefore, the authors conclude, batteries need to be made lighter. They note that up until now, most of the engineering effort involved with batteries has been focused on making them hold more energy so that EVs can travel farther on a charge. But they suggest that focus now needs to include reducing weight. They point out that heavier EVs, in addition to being less efficient because of their weight, pose a danger in collisions with gasoline powered cars due to the weight differential. They note also that heavier vehicles produce more tread wear on tires, which means more roadside pollution.
The authors have several suggestions to help the EV industry reduce its weight problem. The first is to shrink the size of the batteries by using other materials that are more energy dense and removing those that are heavy, such as the liquid electrolytes. They also suggest it should be possible to lighten the frames of EVs that had been made heavier to hold the heavy batteries—again, by using other, lighter materials. They note also that adding technology to reduce crashes could help with acceptance of EVs. And they suggest that efforts could be made by communities to promote less driving. The pandemic, they point out, has shown that more people could be working at home.Why some electric car owners revert back to buying gasoline-powered vehicles
More information:Blake Shaffer et al, Make electric vehicles lighter to maximize climate and safety benefits,Nature(2021).DOI: 10.1038/d41586-021-02760-8
The variety of humble algae that cover the surface of ponds and seas could hold the key to boosting the efficiency of artificial photosynthesis, allowing scientists to produce more energy and lower waste in the process.
A study by Nanyang Technological University, Singapore (NTU Singapore) scientists showed how encasingalgaeprotein inliquid dropletscan dramatically enhance the algae'slight-harvesting and energy-conversion properties, making it up to three times more efficient. This energy is produced as the algae undergoes photosynthesis, which is the process used by plants, algae and certain bacteria to harness energy from sunlight and turn it into chemical energy.
By mimicking how plants convert sunlight into energy, artificial photosynthesis may be a sustainable way of generating electricity that does not rely on fossil fuels or natural gas, which are non-renewable. As the natural energy conversion rate from sunlight to electricity is low, boosting the overall electricity produced could make artificial photosynthesis commercially viable.
The study, led by Assistant Professor Chen Yu-Cheng from the School of Electrical and Electronic Engineering, looked at a particular type of protein found in red algae. These proteins, called phycobiliproteins, are responsible for absorbing light within algae cells to kick-start photosynthesis.
Phycobiliproteins harvest light energy from across the spectral range of light wavelengths, including those which chlorophylls absorb poorly, and convert it to electricity.
Asst Prof Chen said: "Due to their unique light-emitting and photosynthetic properties, phycobiliproteins have promising potential applications in biotechnology and solid-state devices. Boosting the energy from the light-harvesting apparatus has been at the center of development efforts for organic devices that use light as a power source."
Using algae as a source of biological energy is a popular topic of interest in sustainability and renewable energy, as algae usage potentially reduces the amount of toxic by-products created in the manufacturing of solar panels.
The study supports NTU's commitment to sustainability as part of its 2025 strategic plan, which seeks to understand, articulate, and address humanity's impact on the environment
The findings were published and selected as the cover of the scientific journal ACS Applied Materials Interfaces.
Tripling artificial photosynthesis efficiency
Microalgae absorb sunlight and convert it into energy. In order to amplify the amount of energy that algae can generate, the research team developed a method to encase red algae within small liquid crystal micro-droplets that are 20 to 40 microns in size and exposed them to light.
When light hits the droplet, an effect known as the "whispering-gallery mode" occurs, in which light waves travel around the curved edges of the droplet. Light is effectively trapped within the droplet for a longer period of time, giving more opportunity for photosynthesis to take place, hence generating more energy.
The energy generated during photosynthesis in the form of free electrons can then be captured through electrodes as an electrical current.
"The droplet behaves like a resonator that confines a lot of light," said Asst Prof Chen.
"This gives the algae more exposure to light, increasing the rate of photosynthesis. A similar result can be obtained by coating the outside of the droplet with the algae protein too."
"By exploiting microdroplets as a carrier for light-harvesting biomaterials, the strong local electric field enhancement and photon confinement inside the droplet resulted in significantly higher electricity generation," he said.
The droplets can be easily produced in bulk at low cost, making the research team's method widely applicable.
According to Asst Prof Chen, most algae-based solar cells produce an electrical power of 20–30 microwatts per square centimeter (µW/cm2). The NTU algae-droplet combination boosted this level of energy generation by at least two to three times, compared to the energy generation rate of the algae protein alone.
Converting 'bio-trash' to bio-energy
One of the challenges of artificial photosynthesis is generating energy as efficiently as other solar-powered energy sources, such as solar panels. On average, solar panels have an efficiency rating of 15 to 20 percent while artificial photosynthesis is currently estimated to be 4.5 percent efficient.
Asst Prof Chen said: "Artificial photosynthesis is not as efficient as solar cells in generating electricity. However, it is more renewable and sustainable. Due to increasing interest in environmentally-friendly and renewable technologies, extracting energy from light-harvesting proteins in algae has attracted substantial interest in the field of bio-energy."
Asst Prof Chen envisions one potential use case of "algae farms," where densely growing algae in bodies of water could eventually be combined with larger liquid crystal droplets to create floating power generators.
"The micro-droplets used in our experiments have the potential to be scaled up to larger droplets which can then be applied to algae outside of a laboratory environment to create energy. While some might consider algae growth to be unsightly, they play a very important role in the environment. Our findings show that there is a way to convert what some might view as 'bio-trash' into bio-power," said Asst Prof ChenEngineered cyanobacteria uses electricity to turn carbon dioxide into fuel
More information:Zhiyi Yuan et al, Light-Harvesting in Biophotonic Optofluidic Microcavities via Whispering-Gallery Modes,ACS Applied Materials & Interfaces(2021).DOI: 10.1021/acsami.1c09845
As a robotics engineer, Yasemin Ozkan-Aydin, assistant professor of electrical engineering at the University of Notre Dame, gets her inspiration from biological systems. The collective behaviors of ants, honeybees and birds to solve problems and overcome obstacles is something researchers have developed in aerial and underwater robotics. Developing small-scale swarm robots with the capability to traverse complex terrain, however, comes with a unique set of challenges.
In research published inScience Robotics, Ozkan-Aydin presents how she was able to build multi-legged robots capable of maneuvering in challenging environments and accomplishingdifficult taskscollectively, mimicking their natural-world counterparts.
"Legged robots can navigate challenging environments such as rough terrain and tight spaces, and the use of limbs offers effective body support, enables rapid maneuverability and facilitates obstacle crossing," Ozkan-Aydin said. "However, legged robots face unique mobility challenges in terrestrial environments, which results in reduced locomotor performance."
For the study, Ozkan-Aydin said, she hypothesized that a physical connection between individual robots could enhance the mobility of a terrestrial legged collective system. Individual robots performed simple or small tasks such as moving over a smooth surface or carrying a light object, but if the task was beyond the capability of the single unit, the robots physically connected to each other to form a larger multi-legged system and collectively overcome issues.
"When ants collect or transport objects, if one comes upon an obstacle, the group works collectively to overcome that obstacle. If there's a gap in the path, for example, they will form a bridge so the other ants can travel across—and that is the inspiration for this study," she said. "Through robotics we're able to gain a better understanding of the dynamics and collective behaviors of these biological systems and explore how we might be able to use this kind of technology in the future."
Using a 3D printer, Ozkan-Aydin built four-legged robots measuring 15 to 20 centimeters, or roughly 6 to 8 inches, in length. Each was equipped with a lithium polymer battery, microcontroller and three sensors—a light sensor at the front and two magnetic touch sensors at the front and back, allowing the robots to connect to one another. Four flexible legs reduced the need for additional sensors and parts and gave the robots a level of mechanical intelligence, which helped when interacting with rough or uneven terrain.
"You don't need additional sensors to detect obstacles because the flexibility in the legs helps therobotto move right past them," said Ozkan-Aydin. "They can test for gaps in a path, building a bridge with their bodies; move objects individually; or connect to move objects collectively in different types of environments, not dissimilar to ants."
Ozkan-Aydin began her research for the study in early 2020, when much of the country was shut down due to the COVID-19 pandemic. After printing each robot, she built each one and conducted her experiments at home, in her yard or at the playground with her son. The robots were tested over grass, mulch, leaves and acorns. Flat-ground experiments were conducted over particle board, and she built stairs using insulation foam. The robots were also tested over shag carpeting, and rectangular wooden blocks were glued to particle board to serve as rough terrain.
When an individual unit became stuck, a signal was sent to additional robots, which linked together to provide support to successfully traverse obstacles while working collectively.
Ozkan-Aydin says there are still improvements to be made on her design. But she expects the study's findings will inform the design of low-cost legged swarms that can adapt to unforeseen situations and perform real-world cooperative tasks such as search-and-rescue operations, collective object transport, space exploration and environmental monitoring. Her research will focus on improving the control, sensing and power capabilities of the system, which are essential for real-world locomotion and problem-solving—and she plans to use this system to explore the collective dynamics of insects such as ants and termites.
"For functional swarm systems, the battery technology needs to be improved," she said. "We need small batteries that can provide more power, ideally lasting more than 10 hours. Otherwise, using this type of system in the real world isn't sustainable." Additional limitations include the need for more sensors and more powerful motors—while keeping the size of the robots small.
"You need to think about how the robots would function in the real world, so you need to think about how much power is required, the size of the battery you use. Everything is limited so you need to make decisions with every part of the machine."
An online method to allocate tasks to robots on a team during natural disaster scenarios
by Ingrid Fadelli , Tech Xplore
Multi-robot task allocation for a 4-robot team performing a set of ~20 tasks – The top diagram shows the routes traced by 4 robots as they visited different tasks, as decided by simulated execution of our algorithm by each robot; each robot starts and ends at the same depot, marked by the yellow hexagon. The bottom diagram shows how our algorithm works at a particular task-planning instance of the robot R4 (marked by the yellow circle in the top diagram; the location of the peer robots at that instance are marked by the X symbol in the top diagram). Here, the bigraph on the left connects all robots with all available tasks, thus representing various potential allocation strategies. The bigraph on the right is the outcome of robot R4 executing our algorithm, which indicates that robot R4 has now selected to perform task-20 next. Credit: Dr. Payam Ghassemi.
Teams of robots could help users to complete numerous tasks more rapidly and efficiently, as well as keeping human agents out of harm's way during hazardous operations. In recent years, some studies have particularly explored the potential of robot swarms in assisting human agents during search-and-rescue missions; for instance, while seeking out survivors of natural disasters or delivering food and survival kits to them.
Researchers at University of Buffalo have recently developed a technique that could enhance the performance ofrobotteams during disaster response missions. This technique, introduced in a paper published in Elsevier's journalRobotics and Autonomous Systems, is designed to allocate tasks to different robots in a team, so that they can complete missions most effectively.
"Over the past three to four years, we have been exploring unique ways to coordinate large teams of ground robots and drones for assisting in hazard mapping and search-and-rescue operations that are critical to emergency and disaster response applications," Dr. Souma Chowdhury, one of the researchers who led the study, told Tech Xplore. "During these research explorations, we converged upon the need for an algorithm that can quickly (on the go) allocate tasks among robots in the team."
When they reviewed previous research studies, the researchers found that very few of the existing methods for multi-robot task allocation were able to handle simultaneous tasks with strict time deadlines and adapt to new unexpected tasks that may arise during a mission, while also considering the flight range, payload capacity and onboard computing constraints of real-world robots. They thus set out to develop an approach that would successfully do all these things.
"A further objective of our study was to demonstrate the capabilities of this new method on an original flood response application, where a team of drones is employed to quickly deliver or drop survival kits at specified task locations during a simulated flood scenario over a 20x30 km2 area," Dr. Chowdhury said.
In their study, Dr. Chowdhury and his colleague Dr. Payam Ghassemi considered teams of robots and the tasks they are meant to complete as two distinct sets of data. This allowed them to reduce the task of allocating problems to them, so that it primarily entailed mapping or matching pairs of elements from these two sets (i.e., a robot in the team with the task it would complete). Essentially, at any point when the model is required to make a decision, it connects every idle robot in set 1 to one of the tasks remaining in set 2, via an "edge."
"Our technique then uses an incentive function to weight these edges, with a higher weight indicating a higher relative affinity of a robot to undertake the task connected by the concerned edge," Dr. Ghassemi, the other researcher involved in the study, said. "A weighted bigraph matching problem is then solved to produce a one-to-one mapping that yields the immediate next task to be assigned to each robot. By designing the incentive function to account for the robot's global state, the robot's state relative to a task and the remaining time to complete the task, our approach becomes uniquely cognizant of robot's constraints and task deadlines."
The technique has several advantages over alternative, existing optimization-based multi-robot task allocation methods. For instance, its execution times are significantly shorter, as it can make task allocation decisions within a few hundred milliseconds.
In addition to being faster than other existing methods, the researchers' technique alleviates the need for synchronous decision-making among robots. This means that its functioning has a lower dependence on the communication networks connecting robots in a team.
Drs. Chowdhury and Ghassemi evaluated their technique in a series of tests. Remarkably, they found that it could complete the same percentage of tasks as general optimization-based methods that provide provably optimal solutions, yet its computing times were almost 1,000 times lower.
"This observation, along with our technique's ability to make asynchronous decisions, implies that our method could be readily implemented on widely available and inexpensive ground robots and drones," Dr. Chowdhury said. "Such simple robots usually present frugal computing and communication capabilities."
Interestingly, the researchers showed that their method can also be scaled up to tackle highly complex problems that involve teams with up to 100 robots that are meant to complete 1,000 tasks, while retaining its sub-second computing time performance. So far, very few teams have tried to tackle these large-scale problems using existing task allocation tools.
"The outcome of our study represents an important step forward for the multi-robotics community in terms of providing tangible evidence for the vision that very large and scalable teams of robots could revolutionize disaster response and other time sensitive operations," Dr. Chowdhury said. "Lastly, by directly considering the realities of robot's range and payload constraints, task deadlines and appearance of new tasks on the go (the latter are ubiquitous to disaster response operations), our findings take us closer to transitioning multi-robot task allocation algorithms to practice in complex large-scale operations."
In the future, the online multi-robot task allocation technique developed by this team of researchers could facilitate the large-scale deployment of drone swarms or other robot teams during complex search and rescue missions. Meanwhile, Drs. Chowdhury and Ghassemi plan to conduct further experiments to evaluate their algorithm in more realistic simulations, created using contemporary gaming engines. This could finally allow them to deploy and test their technique on real teams of drones and four-wheeled ground robots.
"The University at Buffalo, School of Engineering and Applied Sciences, has recently unveiled a massive state-of-the-art outdoor drone testing facility, which would be a perfect setting for conducting these experiments in real-world conditions," Dr. Chowdhury added. "On a more fundamental level, we plan to alleviate the need for handcrafting the incentive function for different types of operations and robots, and further minimize inter-robot communication needs. To this end, under a new research grant from the National Science Foundation, we are exploring how machine learning approaches can be used to learn incentive functions that will allow our algorithm to generalize over a wide range of real-world scenarios with minimal human inputs."A framework for adaptive task allocation during multi-robot missions
More information:Payam Ghassemi and Souma Chowdhury, Multi-robot task allocation in disaster response: addressing dynamic tasks with deadlines and robots with range and payload constraints,Robotics and Autonomous Systems(2021).DOI: 10.1016/j.robot.2021.103905
