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Wednesday, June 20th, 2018
| Time | Event |
| 12:00a | How to control robots with brainwaves and hand gestures Getting robots to do things isn’t easy: Usually, scientists have to either explicitly program them or get them to understand how humans communicate via language. But what if we could control robots more intuitively, using just hand gestures and brainwaves? A new system spearheaded by researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) aims to do exactly that, allowing users to instantly correct robot mistakes with nothing more than brain signals and the flick of a finger. Building off the team’s past work focused on simple binary-choice activities, the new work expands the scope to multiple-choice tasks, opening up new possibilities for how human workers could manage teams of robots. By monitoring brain activity, the system can detect in real-time if a person notices an error as a robot does a task. Using an interface that measures muscle activity, the person can then make hand gestures to scroll through and select the correct option for the robot to execute. The team demonstrated the system on a task in which a robot moves a power drill to one of three possible targets on the body of a mock plane. Importantly, they showed that the system works on people it’s never seen before, meaning that organizations could deploy it in real-world settings without needing to train it on users. “This work combining EEG and EMG feedback enables natural human-robot interactions for a broader set of applications than we've been able to do before using only EEG feedback,” says CSAIL Director Daniela Rus, who supervised the work. “By including muscle feedback, we can use gestures to command the robot spatially, with much more nuance and specificity.” PhD candidate Joseph DelPreto was lead author on a paper about the project alongside Rus, former CSAIL postdoc Andres F. Salazar-Gomez, former CSAIL research scientist Stephanie Gil, research scholar Ramin M. Hasani, and Boston University Professor Frank H. Guenther. The paper will be presented at the Robotics: Science and Systems (RSS) conference taking place in Pittsburgh next week. In most previous work, systems could generally only recognize brain signals when people trained themselves to “think” in very specific but arbitrary ways and when the system was trained on such signals. For instance, a human operator might have to look at different light displays that correspond to different robot tasks during a training session. Not surprisingly, such approaches are difficult for people to handle reliably, especially if they work in fields like construction or navigation that already require intense concentration. Meanwhile, Rus’ team harnessed the power of brain signals called “error-related potentials” (ErrPs), which researchers have found to naturally occur when people notice mistakes. If there’s an ErrP, the system stops so the user can correct it; if not, it carries on. “What’s great about this approach is that there’s no need to train users to think in a prescribed way,” says DelPreto. “The machine adapts to you, and not the other way around.” For the project the team used “Baxter,” a humanoid robot from Rethink Robotics. With human supervision, the robot went from choosing the correct target 70 percent of the time to more than 97 percent of the time. To create the system the team harnessed the power of electroencephalography (EEG) for brain activity and electromyography (EMG) for muscle activity, putting a series of electrodes on the users’ scalp and forearm. Both metrics have some individual shortcomings: EEG signals are not always reliably detectable, while EMG signals can sometimes be difficult to map to motions that are any more specific than “move left or right.” Merging the two, however, allows for more robust bio-sensing and makes it possible for the system to work on new users without training. “By looking at both muscle and brain signals, we can start to pick up on a person's natural gestures along with their snap decisions about whether something is going wrong,” says DelPreto. “This helps make communicating with a robot more like communicating with another person.” The team says that they could imagine the system one day being useful for the elderly, or workers with language disorders or limited mobility. “We’d like to move away from a world where people have to adapt to the constraints of machines,” says Rus. “Approaches like this show that it’s very much possible to develop robotic systems that are a more natural and intuitive extension of us.” |
| 12:00a | Chip upgrade helps miniature drones navigate Researchers at MIT, who last year designed a tiny computer chip tailored to help honeybee-sized drones navigate, have now shrunk their chip design even further, in both size and power consumption. The team, co-led by Vivienne Sze, associate professor in MIT's Department of Electrical Engineering and Computer Science (EECS), and Sertac Karaman, the Class of 1948 Career Development Associate Professor of Aeronautics and Astronautics, built a fully customized chip from the ground up, with a focus on reducing power consumption and size while also increasing processing speed. The new computer chip, named “Navion,” which they are presenting this week at the Symposia on VLSI Technology and Circuits, is just 20 square millimeters — about the size of a LEGO minifigure’s footprint — and consumes just 24 milliwatts of power, or about 1 one-thousandth the energy required to power a lightbulb. Using this tiny amount of power, the chip is able to process in real-time camera images at up to 171 frames per second, as well as inertial measurements, both of which it uses to determine where it is in space. The researchers say the chip can be integrated into “nanodrones” as small as a fingernail, to help the vehicles navigate, particularly in remote or inaccessible places where global positioning satellite data is unavailable. The chip design can also be run on any small robot or device that needs to navigate over long stretches of time on a limited power supply. “I can imagine applying this chip to low-energy robotics, like flapping-wing vehicles the size of your fingernail, or lighter-than-air vehicles like weather balloons, that have to go for months on one battery,” says Karaman, who is a member of the Laboratory for Information and Decision Systems and the Institute for Data, Systems, and Society at MIT. “Or imagine medical devices like a little pill you swallow, that can navigate in an intelligent way on very little battery so it doesn’t overheat in your body. The chips we are building can help with all of these.” Sze and Karaman’s co-authors are EECS graduate student Amr Suleiman, who is the lead author; EECS graduate student Zhengdong Zhang; and Luca Carlone, who was a research scientist during the project and is now an assistant professor in MIT’s Department of Aeronautics and Astronautics. A flexible chip In the past few years, multiple research groups have engineered miniature drones small enough to fit in the palm of your hand. Scientists envision that such tiny vehicles can fly around and snap pictures of your surroundings, like mosquito-sized photographers or surveyors, before landing back in your palm, where they can then be easily stored away. But a palm-sized drone can only carry so much battery power, most of which is used to make its motors fly, leaving very little energy for other essential operations, such as navigation, and, in particular, state estimation, or a robot’s ability to determine where it is in space. “In traditional robotics, we take existing off-the-shelf computers and implement [state estimation] algorithms on them, because we don’t usually have to worry about power consumption,” Karaman says. “But in every project that requires us to miniaturize low-power applications, we have to now think about the challenges of programming in a very different way.” In their previous work, Sze and Karaman began to address such issues by combining algorithms and hardware in a single chip. Their initial design was implemented on a field-programmable gate array, or FPGA, a commercial hardware platform that can be configured to a given application. The chip was able to perform state estimation using 2 watts of power, compared to larger, standard drones that typically require 10 to 30 watts to perform the same tasks. Still, the chip’s power consumption was greater than the total amount of power that miniature drones can typically carry, which researchers estimate to be about 100 milliwatts. To shrink the chip further, in both size and power consumption, the team decided to build a chip from the ground up rather than reconfigure an existing design. “This gave us a lot more flexibility in the design of the chip,” Sze says. Running in the world To reduce the chip’s power consumption, the group came up with a design to minimize the amount of data — in the form of camera images and inertial measurements — that is stored on the chip at any given time. The design also optimizes the way this data flows across the chip. “Any of the images we would’ve temporarily stored on the chip, we actually compressed so it required less memory,” says Sze, who is a member of the Research Laboratory of Electronics at MIT. The team also cut down on extraneous operations, such as the computation of zeros, which results in a zero. The researchers found a way to skip those computational steps involving any zeros in the data. “This allowed us to avoid having to process and store all those zeros, so we can cut out a lot of unnecessary storage and compute cycles, which reduces the chip size and power, and increases the processing speed of the chip,” Sze says. Through their design, the team was able to reduce the chip’s memory from its previous 2 megabytes, to about 0.8 megabytes. The team tested the chip on previously collected datasets generated by drones flying through multiple environments, such as office and warehouse-type spaces. “While we customized the chip for low power and high speed processing, we also made it sufficiently flexible so that it can adapt to these different environments for additional energy savings,” Sze says. “The key is finding the balance between flexibility and efficiency.” The chip can also be reconfigured to support different cameras and inertial measurement unit (IMU) sensors. From these tests, the researchers found they were able to bring down the chip’s power consumption from 2 watts to 24 milliwatts, and that this was enough to power the chip to process images at 171 frames per second — a rate that was even faster than what the datasets projected. The team plans to demonstrate its design by implementing its chip on a miniature race car. While a screen displays an onboard camera’s live video, the researchers also hope to show the chip determining where it is in space, in real-time, as well as the amount of power that it uses to perform this task. Eventually, the team plans to test the chip on an actual drone, and ultimately on a miniature drone. This research was supported, in part, by the Air Force Office of Scientific Research, and by the National Science Foundation. |
| 12:50p | MIT researchers release evaluation of low-cost cooling devices in Mali Across the Sahel, a semiarid region of western and north-central Africa extending from Senegal to Sudan, many small-scale farmers, market vendors, and families lack an affordable and effective solution for storing and preserving vegetables. As a result, harvested vegetables are at risk of spoiling before they can be sold or eaten. That means loss of income for farmers and vendors, reduced availability of nutritious foods for local communities, and an increase in the time spent traveling to purchase fresh produce. The problem is particularly acute in off-grid areas, and for anyone facing financial or technical barriers to refrigeration. Yet, as described in a recently released report “Evaporative Cooling Technologies for Improved Vegetable Storage in Mali” from MIT’s Comprehensive Initiative on Technology Evaluation (CITE) and the MIT D-Lab, there are low-cost, low-tech solutions for communities in need of produce refrigeration that rely on an age-old method exploiting the air-cooling properties of water evaporation. Made from simple materials such as bricks or clay pots, burlap sack or straw, these devices have the potential to address many of the challenges that face rural households and farmers in need of improved post-harvest vegetable storage. The study was undertaken by a team of researchers led by Eric Verploegen of the D-Lab and Ousmane Sanogo and Takemore Chagomoka from the World Vegetable Center, which is engaged in ongoing work with horticulture cooperatives and farmers in Mali. To gain insight into evaporative cooling device use and preferences, the team conducted interviews in Mali with users of the cooling and storage systems and with stakeholders along the vegetable supply chain. They also deployed sensors to monitor product performance parameters. A great idea in need of a spotlight Despite the potential for evaporative cooling technologies to fill a critical technological need, scant consumer information is available about the range of solutions available. “Evaporative cooling devices for improved vegetable storage have been around for centuries, and we want to provide the kind of information about these technologies that will help consumers decide which products are right for them given their local climate and specific needs,” says Verploegen, the evaluation lead. The simple chambers cool vegetables through the evaporation of water, in the same way that the evaporation of perspiration cools the human body. When water (or perspiration) evaporates, it takes the heat with it. And in less humid climates like Mali, where it is hot and dry, technologies that take advantage of this cooling process show promise for effectively preserving vegetables. The team studied two different categories of vegetable cooling technologies: large-scale vegetable cooling chambers constructed from brick, straw, and sack suitable for farming cooperatives, and devices made from clay pots for individuals and small-scale farmers. Over time, they monitored changes in temperature and humidity inside the devices to understand when they were most effective. “As predicted,” says Verploegen, “the real-world performance of these technologies was stronger in the dry season. We knew this was true in a lab-testing environment, but we now have data that documents that a drop in temperature of greater than 8 degrees Celsius can be achieved in a real-world usage scenario.” The decrease of temperature, along with the increased humidity and protection from pests provided by the devices, resulted in significant increases in shelf life for commonly stored vegetables including tomatoes, cucumbers, eggplant, cabbage, and hot peppers. “The large-scale vegetable cooling devices made of brick performed significantly better than those made out of straw or sacks, both from a technical performance perspective and also from an ease-of-use perspective,” notes Verploegen. “For the small-scale devices, we found fairly similar performance across differing designs, indicating that the design constraints are not very rigid; if the basic principles of evaporative cooling are applied, a reasonably effective device can be made using locally available materials. This is an exciting result. It means that to scale use of this process for keeping vegetables fresh, we are looking at ways to disseminate information and designs rather than developing and distributing physical products.” The research results indicate that evaporative cooling devices would provide great benefit to small-scale farmers, vendors selling vegetables in a market, and individual consumers, who due to financial or energy constraints, don’t have other options. However, evaporative cooling devices are not appropriate for all settings: they are best suited to communities where there is access to water and vegetable storage is needed during hot and dry weather. And, users must be committed to tending the devices. Sensor data used in the study revealed that users were more inclined to water the cooling devices in the dry season and reduce their usage of the devices as the rainy season started. Resources for development researchers and practitioners In addition to the evaluation report, Verploegen has developed two practitioner resources, the “Evaporative Cooling Decision Making Tool” (which is interactive) and the “Evaporative Cooling Best Practices Guide,” to support the determination of evaporative cooler suitability and facilitate the devices’ proper construction and use. The intended audience for these resources includes government agencies, nongovernmental organizations, civil society organizations, and businesses that could produce, distribute, and/or promote these technologies. Both resources are available online. As part of an ongoing project, the MIT D-Lab and the World Vegetable Center are using the results of this research to test various approaches to increase dissemination of these technologies in the communities that can most benefit from them. “This study provided us with the evidence that convinced us to use only the efficient types of vegetable cooling technologies — the larger brick chambers,” says World Vegetable Center plant health scientist Wubetu Bihon Legesse. “And, the decision support tool helped us evaluate the suitability of evaporative cooling systems before installing them.” Launched at MIT in 2012, CITE is a pioneering program dedicated to developing methods for product evaluation in global development. Currently based at MIT D-Lab, CITE’s research is funded by the USAID U.S. Global Development Lab. CITE is led by Professor Dan Frey of the Department of Mechanical Engineering and MIT D-Lab, and additionally supported by MIT faculty and staff from the Priscilla King Gray Public Service Center, the Sociotechnical Systems Research Center, the Center for Transportation and Logistics, the School of Engineering, and the Sloan School of Management. |
| 1:00p | Biologists discover how pancreatic tumors lead to weight loss Patients with pancreatic cancer usually experience significant weight loss, which can begin very early in the disease. A new study from MIT and Dana-Farber Cancer Institute offers insight into how this happens, and suggests that the weight loss may not necessarily affect patients’ survival. In a study of mice, the researchers found that weight loss occurs due to a reduction in key pancreatic enzymes that normally help digest food. When the researchers treated these mice with replacement enzymes, they were surprised to find that while the mice did regain weight, they did not survive any longer than untreated mice. Pancreatic cancer patients are sometimes given replacement enzymes to help them gain weight, but the new findings suggest that more study is needed to determine whether that actually benefits patients, says Matt Vander Heiden, an associate professor of biology at MIT and a member of the Koch Institute for Integrative Cancer Research. “We have to be very careful not to draw medical advice from a mouse study and apply it to humans,” Vander Heiden says. “The study does raise the question of whether enzyme replacement is good or bad for patients, which needs to be studied in a clinical trial.” Vander Heiden and Brian Wolpin, an associate professor of medicine at Harvard Medical School and Dana-Farber Cancer Institute, are the senior authors of the study, which appears in the June 20 issue of Nature. The paper’s lead authors are Laura Danai, a former MIT postdoc, and Ana Babic, an instructor in medicine at Dana-Farber. Starvation mode In a 2014 study, Vander Heiden and his colleagues found that muscle starts breaking down very early in pancreatic cancer patients, usually long before any other signs of the disease appear. Still unknown was how this tissue wasting process occurs. One hypothesis was that pancreatic tumors overproduce some kind of signaling factor, such as a hormone, that circulates in the bloodstream and promotes breakdown of muscle and fat. However, in their new study, the MIT and Dana-Farber researchers found that this was not the case. Instead, they discovered that even very tiny, early-stage pancreatic tumors can impair the production of key digestive enzymes. Mice with these early-stage tumors lost weight even though they ate the same amount of food as normal mice. These mice were unable to digest all of their food, so they went into a starvation mode where the body begins to break down other tissues, especially fat. The researchers found that when they implanted pancreatic tumor cells elsewhere in the body, this weight loss did not occur. That suggests the tumor cells are not secreting a weight-loss factor that circulates in the bloodstream; instead, they only stimulate tissue wasting when they are in the pancreas. The researchers then explored whether reversing this weight loss would improve survival. Treating the mice with pancreatic enzymes did reverse the weight loss. However, these mice actually survived for a shorter period of time than mice that had pancreatic tumors but did not receive the enzymes. That finding, while surprising, is consistent with studies in mice that have shown that calorie restriction can have a protective effect against cancer and other diseases. “It turns out that this mechanism of tissue wasting is actually protective, at least for the mice, in the same way that limiting calories can be protective for mice,” Vander Heiden says. Human connection The intriguing findings from the mouse study prompted the research team to see if they could find any connection between weight loss and survival in human patients. In an analysis of medical records and blood samples from 782 patients, they found no link between degree of tissue wasting at the time of diagnosis and length of survival. That finding is important because it could reassure patients that weight loss does not necessarily mean that the patient will do worse, Vander Heiden says. “Sometimes you can’t do anything about this weight loss, and this finding may mean that just because the patient is eating less and is losing weight, that doesn’t necessarily mean that they’re shortening their life,” he says. The researchers say that more study is needed to determine if the same mechanism they discovered in mice is also occurring in human cancer patients. Because the mechanism they found is very specific to pancreatic tumors, it may differ from the underlying causes behind tissue wasting seen in other types of cancer and diseases such as HIV. “From a mechanistic standpoint, this study reveals a very different way to think about what could be causing at least some weight loss in pancreatic cancer, suggesting that not all weight loss is the same across different cancers,” Vander Heiden says. “And it raises questions that we really need to study more, because some mechanisms may be protective and some mechanisms may be bad for you.” Clary Clish, director of the Metabolomics Platform at the Broad Institute, and members of his research group also contributed to this work. The research was funded, in part, by the Lustgarten Foundation, a National Institutes of Health Ruth Kirschstein Fellowship, Stand Up 2 Cancer, the Ludwig Center for Molecular Oncology at MIT, the Koch Institute Frontier Research Program through the Kathy and Curt Marble Cancer Research Fund, the MIT Center for Precision Cancer Medicine, and the National Institutes of Health. |
| 11:59p | Nearly 80 exoplanet candidates identified in record time Scientists at MIT and elsewhere have analyzed data from K2, the follow-up mission to NASA’s Kepler Space Telescope, and have discovered a trove of possible exoplanets amid some 50,000 stars. In a paper that appears online today in The Astronomical Journal, the scientists report the discovery of nearly 80 new planetary candidates, including a particular standout: a likely planet that orbits the star HD 73344, which would be the brightest planet host ever discovered by the K2 mission. The planet appears to orbit HD 73344 every 15 days, and based on the amount of light that it blocks each time it passes in front of its star, scientists estimate that the planet is about 2.5 times the size of the Earth and 10 times as massive. It is also likely incredibly hot, with a temperature somewhere in the range of 1,200 to 1,300 degrees Celsius, or around 2,000 degrees Fahrenheit — about the the temperature of lava from an erupting volcano. The planet lies at a relatively close distance of 35 parsecs, or about 114 light years from Earth. Given its proximity and the fact that it orbits a very bright star, scientists believe the planet is an ideal candidate for follow-up studies to determine its atmospheric composition and other characteristics. “We think it would probably be more like a smaller, hotter version of Uranus or Neptune,” says Ian Crossfield, an assistant professor of physics at MIT who co-led the study with graduate student Liang Yu. The new analysis is also noteworthy for the speed with which it was performed. The researchers were able to use existing tools developed at MIT to rapidly search through graphs of light intensity called “lightcurves” from each of the 50,000 stars that K2 monitored in its two recent observing campaigns. They quickly identified the planetary candidates and released the information to the astronomy community just weeks after the K2 mission made the spacecraft’s raw data available. A typical analysis of this kind takes between several months and a year. Crossfield says such a fast planet-search enables astronomers to follow up with ground-based telescopes much sooner than they otherwise would, giving them a chance to catch a glimpse of planetary candidates before the Earth passes by that particular patch of sky on its way around the sun. Such speed will also be a necessity when scientists start receiving data from NASA’s Transiting Exoplanet Survey Satellite, TESS, which is designed to monitor nearby stars in 30-day swaths and will ultimately cover nearly the entire sky. “When the TESS data come down, there’ll be a few months before all of the stars that TESS looked at for that month ‘set’ for the year,” Crossfield says. “If we get candidates out quickly to the community, everyone can start immediately observing systems discovered by TESS, and doing a lot of great planetary science. So this [analysis] was really a dress rehearsal for TESS.” Speed dips The team analyzed data from K2’s 16th and 17th observing campaigns, known as C16 and C17. During each campaign, K2 observes one patch of the sky for 80 days. The telescope is on an orbit that trails the Earth as it travels around the sun. For most other campaigns, K2 has been in a “rear-facing” orientation, in which the telescope observes those stars that are essentially in its rear-view mirror.
Since the telescope travels behind the Earth, those stars that it observes are typically not observable by scientists until the planet circles back around the sun to that particular patch of sky, nearly a year later. Thus, for rear-facing campaigns, Crossfield says there has been little motivation to analyze K2 data quickly. The C16 and C17 campaigns, on the other hand, were forward-facing; K2 observed those stars that were in front of the telescope and within Earth’s field of view, at least for the next several months. Crossfield, Yu, and their colleagues took this as an opportunity to speed up the usual analysis of K2 data, to give astronomers a chance to quickly observe planetary candidates before the Earth passed them by. During C16, K2 observed 20,647 stars over 80 days, between Dec. 7, 2017, and Feb. 25, 2018. On Feb. 28, the mission released the data, in the form of pixel-level images, to the astronomy community. Yu and Crossfield immediately began to sift through the data, using algorithms developed at MIT to winnow down the field from 20,000-some stars to 1,000 stars of interest. The team then worked around the clock, looking through these 1,000 stars by eye for signs of transits, or periodic dips in starlight that could signal a passing planet. In the end, they discovered 30 “highest-quality” planet candidates, whose periodic signatures are especially likely to be caused by transiting planets. “Our experience with four years of K2 data leads us to believe that most of these are indeed real planets, ready to be confirmed or statistically validated,” the researchers write in their paper. They also identified a similar number of planet candidates in the recent C17 analysis. In addition to these planetary candidates, the group also picked out hundreds of periodic signals that could be signatures of astrophysical phenomena, such as pulsating or rotating stars, and at least one supernova in another galaxy. Stars in spades While the nature of a star doesn’t typically change over the course of a year, Crossfield says the sooner researchers can follow up on a possible planetary transit, the better chance there is of confirming that a planet actually exists. “You want to observe [candidates] again relatively soon so you don’t lose the transit altogether,” Crossfield says. “You might be able to say, ‘I know there’s a planet around that star, but I’m no longer at all certain when the transits will happen.’ That’s another motivation for following these things up more quickly.” Since the team released its results, astronomers have validated four of the candidates as definite exoplanets. They have been observing other candidates that the study identified, including the possible planet orbiting HD 73344. Crossfield says the brightness of this star, combined with the speed with which its planetary candidate was identified, can help astronomers quickly zero in on even more specific features of this system. “We found one of the most exciting planets that K2 has found in its entire mission, and we did it more rapidly than any effort has done before,” Crossfield says. “This is showing the path forward for how the TESS mission is going to do the same thing in spades, all over the entire sky, for the next several years.” This research was supported, in part, by NASA and the National Science Foundation. |
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