MIT News: Sustainability

June 20, 2018

  • Daniel E. Hastings, the Cecil and Ida Green Education Professor at MIT, has been named head of the Department of Aeronautics and Astronautics, effective Jan. 1, 2019.

    “Dan has a remarkable depth of knowledge about MIT, and has served the Institute in a wide range of capacities,” says Anantha Chandrakasan, dean of the School of Engineering. “He has been a staunch advocate for students, for research, and for MIT’s international activities. We are fortunate to have him join the School of Engineering’s leadership team, and I look forward to working with him.”

    Hastings, whose contributions to spacecraft and space system-environment interactions, space system architecture, and leadership in aerospace research and education earned him election to the National Academy of Engineering in 2017, has held a range of roles involving research, education, and administration at MIT.

    Hastings has taught courses in space environment interactions, rocket propulsion, advanced space power and propulsion systems, space policy and space systems engineering since he first joined the faculty in 1985. He became director of the MIT Technology and Policy Program in 2000 and was named director of the Engineering Systems Division in 2004. He served as dean for undergraduate education from 2006 to 2013, and from 2014 to 2018 he has been director of the Singapore-MIT Alliance for Research and Technology (SMART).

    Hastings has also had an active career of service outside MIT. His many external appointments include serving as chief scientist from 1997 to 1999 for the U.S. Air Force, where he led influential studies of Air Force investments in space and of preparations for a 21st-century science and technology workforce. He was also the chair of the Air Force Scientific Advisory Board from 2002 to 2005; from 2002 to 2008, he was a member of the National Science Board.

    A fellow of the American Institute of Aeronautics and Astronautics (AIAA), Hastings was also awarded the Losey Atmospheric Sciences Award from the AIAA in 2002. He is a fellow (academician) of the International Astronautical Federation and the International Council in System Engineering. The U.S Air Force granted him its Exceptional Service Award in 2008, and in both 1997 and 1999 gave him the Air Force Distinguished Civilian Award. He received the National Reconnaissance Office Distinguished Civilian Award in 2003. He was also the recipient of MIT’s Gordon Billard Award for “special service of outstanding merit performed for the Institute” in 2013.

    Hastings received his bachelor’s degree from Oxford University in 1976, and MS and PhD degrees in aeronautics and astronautics from MIT in 1978 and 1980, respectively. 

    Edward M. Greitzer, the H.N. Slater Professor of Aeronautics and Astronautics, will serve as interim department head from July 1 to Dec. 31, 2018.  

    Hastings will replace Jaime Peraire, the H. N. Slater Professor in Aeronautics and Astronautics, who has been department head since July 1, 2011. “I am grateful to Jaime for his excellent work over the last seven years,” Chandrakasan noted. “During his tenure as department head, he led the creation of a new strategic plan and made significant steps in its implementation. He addressed the department's facilities challenges, strengthened student capstone- and research-project experience, and led the 2014 AeroAstro centennial celebrations, which highlighted the tremendous contributions MIT has made to aerospace and national service.”

  • 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.

  • 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.”

  • 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.

June 19, 2018

  • MIT and the Southern University of Science and Technology (SUSTech) in Shenzhen, China, have announced the launch of the Centers for Mechanical Engineering Research and Education at MIT and SUSTech. The two centers, which will be located at MIT and SUSTech, aim to foster research collaborations and inspire new approaches to engineering education.

    At a ceremony on June 15, Anantha P. Chandrakasan, dean of engineering at MIT and the Vannevar Bush Professor of Electrical Engineering and Computer Science, and Zhenghe Xu, dean of engineering at SUSTech, signed an agreement establishing the two centers. They were joined by faculty from both MIT’s Department of Mechanical Engineering and SUSTech as well as representatives from the local Shenzhen government.

    “This research and educational collaboration will give MIT’s faculty and students the opportunity to benefit from a wider range of research and engage in a discussion on how to best train mechanical engineers,” says Gang Chen, the Carl Richard Soderberg Professor of Power Engineering and head of the Department of Mechanical Engineering, who will serve as faculty director for the MIT center. Professor Zhenghe Xu will serve as faculty director of the SUSTech center.

    “Launching these new centers will help support research on some of the world’s most pressing problems,” Chen says.

    “The Centers for Mechanical Engineering Research and Education at MIT and SUSTech aim to inspire intellectual dialogue, innovative research and development, and new approaches to teaching and learning between experts in China and at MIT,” says MIT Associate Provost Richard Lester.

    Each year, one or two faculty members from SUSTech will visit MIT for a semester. In addition to conducting research at the MIT center, the SUSTech faculty will be invited to observe MIT’s approach to mechanical engineering education firsthand.

    Students from SUSTech will also have the opportunity to conduct research and take courses at MIT. Roughly a dozen graduate and undergraduate students from SUSTech will spend time at the MIT center each year.

    Meanwhile, faculty and students from MIT will be invited to travel to Shenzhen and observe developments in the area’s innovation ecosystem, through a number of programs supported by the Centers for Mechanical Engineering Research and Education at MIT and SUSTech.

    “Our collaboration with SUSTech on launching these two new centers can help us make a positive impact on research and education both in the U.S. and in China,” Chen says.