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By Jennifer Chu

When it comes to processing power, the human brain just can’t be beat.

Packed within the squishy, football-sized organ are somewhere around 100 billion neurons. At any given moment, a single neuron can relay instructions to thousands of other neurons via synapses — the spaces between neurons, across which neurotransmitters are exchanged. There are more than 100 trillion synapses that mediate neuron signaling in the brain, strengthening some connections while pruning others, in a process that enables the brain to recognize patterns, remember facts, and carry out other learning tasks, at lightning speeds.

Researchers in the emerging field of “neuromorphic computing” have attempted to design computer chips that work like the human brain. Instead of carrying out computations based on binary, on/off signaling, like digital chips do today, the elements of a “brain on a chip” would work in an analog fashion, exchanging a gradient of signals, or “weights,” much like neurons that activate in various ways depending on the type and number of ions that flow across a synapse.

In this way, small neuromorphic chips could, like the brain, efficiently process millions of streams of parallel computations that are currently only possible with large banks of supercomputers. But one significant hangup on the way to such portable artificial intelligence has been the neural synapse, which has been particularly tricky to reproduce in hardware.

Now engineers at MIT have designed an artificial synapse in such a way that they can precisely control the strength of an electric current flowing across it, similar to the way ions flow between neurons. The team has built a small chip with artificial synapses, made from silicon germanium. In simulations, the researchers found that the chip and its synapses could be used to recognize samples of handwriting, with 95 percent accuracy.

The design, published today in the journal Nature Materials, is a major step toward building portable, low-power neuromorphic chips for use in pattern recognition and other learning tasks.

The research was led by Jeehwan Kim, the Class of 1947 Career Development Assistant Professor in the departments of Mechanical Engineering and Materials Science and Engineering, and a principal investigator in MIT’s Research Laboratory of Electronics and Microsystems Technology Laboratories. His co-authors are Shinhyun Choi (first author), Scott Tan (co-first author), Zefan Li, Yunjo Kim, Chanyeol Choi, and Hanwool Yeon of MIT, along with Pai-Yu Chen and Shimeng Yu of Arizona State University.

Too many paths

Most neuromorphic chip designs attempt to emulate the synaptic connection between neurons using two conductive layers separated by a “switching medium,” or synapse-like space. When a voltage is applied, ions should move in the switching medium to create conductive filaments, similarly to how the “weight” of a synapse changes.

But it’s been difficult to control the flow of ions in existing designs. Kim says that’s because most switching mediums, made of amorphous materials, have unlimited possible paths through which ions can travel — a bit like Pachinko, a mechanical arcade game that funnels small steel balls down through a series of pins and levers, which act to either divert or direct the balls out of the machine.

Like Pachinko, existing switching mediums contain multiple paths that make it difficult to predict where ions will make it through. Kim says that can create unwanted nonuniformity in a synapse’s performance.

“Once you apply some voltage to represent some data with your artificial neuron, you have to erase and be able to write it again in the exact same way,” Kim says. “But in an amorphous solid, when you write again, the ions go in different directions because there are lots of defects. This stream is changing, and it’s hard to control. That’s the biggest problem — nonuniformity of the artificial synapse.”

A perfect mismatch

Instead of using amorphous materials as an artificial synapse, Kim and his colleagues looked to single-crystalline silicon, a defect-free conducting material made from atoms arranged in a continuously ordered alignment. The team sought to create a precise, one-dimensional line defect, or dislocation, through the silicon, through which ions could predictably flow.

To do so, the researchers started with a wafer of silicon, resembling, at microscopic resolution, a chicken-wire pattern. They then grew a similar pattern of silicon germanium — a material also used commonly in transistors — on top of the silicon wafer. Silicon germanium’s lattice is slightly larger than that of silicon, and Kim found that together, the two perfectly mismatched materials can form a funnel-like dislocation, creating a single path through which ions can flow. 

The researchers fabricated a neuromorphic chip consisting of artificial synapses made from silicon germanium, each synapse measuring about 25 nanometers across. They applied voltage to each synapse and found that all synapses exhibited more or less the same current, or flow of ions, with about a 4 percent variation between synapses — a much more uniform performance compared with synapses made from amorphous material.

They also tested a single synapse over multiple trials, applying the same voltage over 700 cycles, and found the synapse exhibited the same current, with just 1 percent variation from cycle to cycle.

“This is the most uniform device we could achieve, which is the key to demonstrating artificial neural networks,” Kim says.

Writing, recognized

As a final test, Kim’s team explored how its device would perform if it were to carry out actual learning tasks — specifically, recognizing samples of handwriting, which researchers consider to be a first practical test for neuromorphic chips. Such chips would consist of “input/hidden/output neurons,” each connected to other “neurons” via filament-based artificial synapses.

Scientists believe such stacks of neural nets can be made to “learn.” For instance, when fed an input that is a handwritten ‘1,’ with an output that labels it as ‘1,’ certain output neurons will be activated by input neurons and weights from an artificial synapse. When more examples of handwritten ‘1s’ are fed into the same chip, the same output neurons may be activated when they sense similar features between different samples of the same letter, thus “learning” in a fashion similar to what the brain does.

Kim and his colleagues ran a computer simulation of an artificial neural network consisting of three sheets of neural layers connected via two layers of artificial synapses, the properties of which they based on measurements from their actual neuromorphic chip. They fed into their simulation tens of thousands of samples from a handwritten recognition dataset commonly used by neuromorphic designers, and found that their neural network hardware recognized handwritten samples 95 percent of the time, compared to the 97 percent accuracy of existing software algorithms.

The team is in the process of fabricating a working neuromorphic chip that can carry out handwriting-recognition tasks, not in simulation but in reality. Looking beyond handwriting, Kim says the team’s artificial synapse design will enable much smaller, portable neural network devices that can perform complex computations that currently are only possible with large supercomputers.

“Ultimately we want a chip as big as a fingernail to replace one big supercomputer,” Kim says. “This opens a stepping stone to produce real artificial hardware.”

This research was supported in part by the National Science Foundation.

Josh Tenenbaum, a professor of brain and cognitive sciences at MIT, directs research on the development of intelligence at the Center for Brains, Minds, and Machines, a multiuniversity, multidisciplinary project based at MIT that seeks to explain and replicate human intelligence.

Presenting their work at this year’s Conference on Neural Information Processing Systems, Tenenbaum and one of his students, Jiajun Wu, are co-authors on four papers that examine the fundamental cognitive abilities that an intelligent agent requires to navigate the world: discerning distinct objects and inferring how they respond to physical forces.

By building computer systems that begin to approximate these capacities, the researchers believe they can help answer questions about what information-processing resources human beings use at what stages of development. Along the way, the researchers might also generate some insights useful for robotic vision systems.

“The common theme here is really learning to perceive physics,” Tenenbaum says. “That starts with seeing the full 3-D shapes of objects, and multiple objects in a scene, along with their physical properties, like mass and friction, then reasoning about how these objects will move over time. Jiajun’s four papers address this whole space. Taken together, we’re starting to be able to build machines that capture more and more of people’s basic understanding of the physical world.”

Three of the papers deal with inferring information about the physical structure of objects, from both visual and aural data. The fourth deals with predicting how objects will behave on the basis of that data.

Two-way street

Something else that unites all four papers is their unusual approach to machine learning, a technique in which computers learn to perform computational tasks by analyzing huge sets of training data. In a typical machine-learning system, the training data are labeled: Human analysts will have, say, identified the objects in a visual scene or transcribed the words of a spoken sentence. The system attempts to learn what features of the data correlate with what labels, and it’s judged on how well it labels previously unseen data.

In Wu and Tenenbaum’s new papers, the system is trained to infer a physical model of the world — the 3-D shapes of objects that are mostly hidden from view, for instance. But then it works backward, using the model to resynthesize the input data, and its performance is judged on how well the reconstructed data matches the original data.

For instance, using visual images to build a 3-D model of an object in a scene requires stripping away any occluding objects; filtering out confounding visual textures, reflections, and shadows; and inferring the shape of unseen surfaces. Once Wu and Tenenbaum’s system has built such a model, however, it rotates it in space and adds visual textures back in until it can approximate the input data.

Indeed, two of the researchers’ four papers address the complex problem of inferring 3-D models from visual data. On those papers, they’re joined by four other MIT researchers, including William Freeman, the Perkins Professor of Electrical Engineering and Computer Science, and by colleagues at DeepMind, ShanghaiTech University, and Shanghai Jiao Tong University.

Divide and conquer

The researchers’ system is based on the influential theories of the MIT neuroscientist David Marr, who died in 1980 at the tragically young age of 35. Marr hypothesized that in interpreting a visual scene, the brain first creates what he called a 2.5-D sketch of the objects it contained — a representation of just those surfaces of the objects facing the viewer. Then, on the basis of the 2.5-D sketch — not the raw visual information about the scene — the brain infers the full, three-dimensional shapes of the objects.

“Both problems are very hard, but there’s a nice way to disentangle them,” Wu says. “You can do them one at a time, so you don’t have to deal with both of them at the same time, which is even harder.”

Wu and his colleagues’ system needs to be trained on data that include both visual images and 3-D models of the objects the images depict. Constructing accurate 3-D models of the objects depicted in real photographs would be prohibitively time consuming, so initially, the researchers train their system using synthetic data, in which the visual image is generated from the 3-D model, rather than vice versa. The process of creating the data is like that of creating a computer-animated film.

Once the system has been trained on synthetic data, however, it can be fine-tuned using real data. That’s because its ultimate performance criterion is the accuracy with which it reconstructs the input data. It’s still building 3-D models, but they don’t need to be compared to human-constructed models for performance assessment.

In evaluating their system, the researchers used a measure called intersection over union, which is common in the field. On that measure, their system outperforms its predecessors. But a given intersection-over-union score leaves a lot of room for local variation in the smoothness and shape of a 3-D model. So Wu and his colleagues also conducted a qualitative study of the models’ fidelity to the source images. Of the study’s participants, 74 percent preferred the new system’s reconstructions to those of its predecessors.

All that fall

In another of Wu and Tenenbaum’s papers, on which they’re joined again by Freeman and by researchers at MIT, Cambridge University, and ShanghaiTech University, they train a system to analyze audio recordings of an object being dropped, to infer properties such as the object’s shape, its composition, and the height from which it fell. Again, the system is trained to produce an abstract representation of the object, which, in turn, it uses to synthesize the sound the object would make when dropped from a particular height. The system’s performance is judged on the similarity between the synthesized sound and the source sound.

Finally, in their fourth paper, Wu, Tenenbaum, Freeman, and colleagues at DeepMind and Oxford University describe a system that begins to model humans’ intuitive understanding of the physical forces acting on objects in the world. This paper picks up where the previous papers leave off: It assumes that the system has already deduced objects’ 3-D shapes.

Those shapes are simple: balls and cubes. The researchers trained their system to perform two tasks. The first is to estimate the velocities of balls traveling on a billiard table and, on that basis, to predict how they will behave after a collision. The second is to analyze a static image of stacked cubes and determine whether they will fall and, if so, where the cubes will land.

Wu developed a representational language he calls scene XML that can quantitatively characterize the relative positions of objects in a visual scene. The system first learns to describe input data in that language. It then feeds that description to something called a physics engine, which models the physical forces acting on the represented objects. Physics engines are a staple of both computer animation, where they generate the movement of clothing, falling objects, and the like, and of scientific computing, where they’re used for large-scale physical simulations.

After the physics engine has predicted the motions of the balls and boxes, that information is fed to a graphics engine, whose output is, again, compared with the source images. As with the work on visual discrimination, the researchers train their system on synthetic data before refining it with real data.

In tests, the researchers’ system again outperformed its predecessors. In fact, in some of the tests involving billiard balls, it frequently outperformed human observers as well.

By Larry Hardesty

Neural networks, which learn to perform computational tasks by analyzing huge sets of training data, have been responsible for the most impressive recent advances in artificial intelligence, including speech-recognition and automatic-translation systems.

During training, however, a neural net continually adjusts its internal settings in ways that even its creators can’t interpret. Much recent work in computer science has focused on clever techniques for determining just how neural nets do what they do.

In several recent papers, researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) and the Qatar Computing Research Institute have used a recently developed interpretive technique, which had been applied in other areas, to analyze neural networks trained to do machine translation and speech recognition.

They find empirical support for some common intuitions about how the networks probably work. For example, the systems seem to concentrate on lower-level tasks, such as sound recognition or part-of-speech recognition, before moving on to higher-level tasks, such as transcription or semantic interpretation.

But the researchers also find a surprising omission in the type of data the translation network considers, and they show that correcting that omission improves the network’s performance. The improvement is modest, but it points toward the possibility that analysis of neural networks could help improve the accuracy of artificial intelligence systems.

“In machine translation, historically, there was sort of a pyramid with different layers,” says Jim Glass, a CSAIL senior research scientist who worked on the project with Yonatan Belinkov, an MIT graduate student in electrical engineering and computer science. “At the lowest level there was the word, the surface forms, and the top of the pyramid was some kind of interlingual representation, and you’d have different layers where you were doing syntax, semantics. This was a very abstract notion, but the idea was the higher up you went in the pyramid, the easier it would be to translate to a new language, and then you’d go down again. So part of what Yonatan is doing is trying to figure out what aspects of this notion are being encoded in the network.”

The work on machine translation was presented recently in two papers at the International Joint Conference on Natural Language Processing. On one, Belinkov is first author, and Glass is senior author, and on the other, Belinkov is a co-author. On both, they’re joined by researchers from the Qatar Computing Research Institute (QCRI), including Lluís Màrquez, Hassan Sajjad, Nadir Durrani, Fahim Dalvi, and Stephan Vogel. Belinkov and Glass are sole authors on the paper analyzing speech recognition systems, which Belinkov presented at the Neural Information Processing Symposium last week.

Leveling down

Neural nets are so named because they roughly approximate the structure of the human brain. Typically, they’re arranged into layers, and each layer consists of many simple processing units — nodes — each of which is connected to several nodes in the layers above and below. Data are fed into the lowest layer, whose nodes process it and pass it to the next layer. The connections between layers have different “weights,” which determine how much the output of any one node figures into the calculation performed by the next.

During training, the weights between nodes are constantly readjusted. After the network is trained, its creators can determine the weights of all the connections, but with thousands or even millions of nodes, and even more connections between them, deducing what algorithm those weights encode is nigh impossible.

The MIT and QCRI researchers’ technique consists of taking a trained network and using the output of each of its layers, in response to individual training examples, to train another neural network to perform a particular task. This enables them to determine what task each layer is optimized for.

In the case of the speech recognition network, Belinkov and Glass used individual layers’ outputs to train a system to identify “phones,” distinct phonetic units particular to a spoken language. The “t” sounds in the words “tea,” “tree,” and “but,” for instance, might be classified as separate phones, but a speech recognition system has to transcribe all of them using the letter “t.” And indeed, Belinkov and Glass found that lower levels of the network were better at recognizing phones than higher levels, where, presumably, the distinction is less important.

Similarly, in an earlier paper, presented last summer at the Annual Meeting of the Association for Computational Linguistics, Glass, Belinkov, and their QCRI colleagues showed that the lower levels of a machine-translation network were particularly good at recognizing parts of speech and morphology — features such as tense, number, and conjugation.

Making meaning

But in the new paper, they show that higher levels of the network are better at something called semantic tagging. As Belinkov explains, a part-of-speech tagger will recognize that “herself” is a pronoun, but the meaning of that pronoun — its semantic sense — is very different in the sentences “she bought the book herself” and “she herself bought the book.” A semantic tagger would assign different tags to those two instances of “herself,” just as a machine translation system might find different translations for them in a given target language.

The best-performing machine-translation networks use so-called encoding-decoding models, so the MIT and QCRI researchers’ network uses it as well. In such systems, the input, in the source language, passes through several layers of the network — known as the encoder — to produce a vector, a string of numbers that somehow represent the semantic content of the input. That vector passes through several more layers of the network — the decoder — to yield a translation in the target language.

Although the encoder and decoder are trained together, they can be thought of as separate networks. The researchers discovered that, curiously, the lower layers of the encoder are good at distinguishing morphology, but the higher layers of the decoder are not. So Belinkov and the QCRI researchers retrained the network, scoring its performance according to not only accuracy of translation but also analysis of morphology in the target language. In essence, they forced the decoder to get better at distinguishing morphology.

Using this technique, they retrained the network to translate English into German and found that its accuracy increased by 3 percent. That’s not an overwhelming improvement, but it’s an indication that looking under the hood of neural networks could be more than an academic exercise.

Just in time for Halloween, a research team from the MIT Media Lab’s Scalable Cooperation group has introduced Shelley: the world’s first artificial intelligence-human horror story collaboration.

Shelley, named for English writer Mary Shelley — best known as the author of “Frankenstein: or, the Modern Prometheus” — is a deep-learning powered artificial intelligence (AI) system that was trained on over 140,000 horror stories on Reddit’s infamous r/nosleep subreddit. She lives on Twitter, where every hour, @shelley_ai tweets out the beginning of a new horror story and the hashtag #yourturn to invite a human collaborator. Anyone is welcome to reply to the tweet with the next part of the story, then Shelley will reply again with the next part, and so on. The results are weird, fun, and unpredictable horror stories that represent both creativity and collaboration — traits that explore the limits of artificial intelligence and machine learning.

“Shelley is a combination of a multi-layer recurrent neural network and an online learning algorithm that learns from crowd’s feedback over time,” explains Pinar Yanardhag, the project’s lead researcher. “The more collaboration Shelley gets from people, the more and scarier stories she will write.”

Shelley starts stories based on the AI’s own learning dataset, but she responds directly to additions to the story from human contributors — which, in turn, adds to her knowledge base. Each completed story is then collected on the Shelley project website.

“Shelley’s creative mind has no boundaries,” the research team says. “She writes stories about a pregnant man who woke up in a hospital, a mouth on the floor with a calm smile, an entire haunted town, a faceless man on the mirror anything is possible!”

One final note on Shelley: The AI was trained on a subreddit filled with adult content, and the researchers have limited control over her — so parents beware.

Certain industries have traditionally not had the luxury of telecommuting. Many manufacturing jobs, for example, require a physical presence to operate machinery.

But what if such jobs could be done remotely? Last week researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) presented a virtual reality (VR) system that lets you teleoperate a robot using an Oculus Rift headset.

The system embeds the user in a VR control room with multiple sensor displays, making it feel like they’re inside the robot’s head. By using hand controllers, users can match their movements to the robot’s movements to complete various tasks.

“A system like this could eventually help humans supervise robots from a distance,” says CSAIL postdoc Jeffrey Lipton, who was the lead author on a related paper about the system. “By teleoperating robots from home, blue-collar workers would be able to tele-commute and benefit from the IT revolution just as white-collars workers do now.”  

The researchers even imagine that such a system could help employ increasing numbers of jobless video-gamers by “gameifying” manufacturing positions.

The team used the Baxter humanoid robot from Rethink Robotics, but said that it can work on other robot platforms and is also compatible with the HTC Vive headset.

Lipton co-wrote the paper with CSAIL Director Daniela Rus and researcher Aidan Fay. They presented the paper at the recent IEEE/RSJ International Conference on Intelligent Robots and Systems in Vancouver.

There have traditionally been two main approaches to using VR for teleoperation.

In a direct model, the user’s vision is directly coupled to the robot’s state. With these systems, a delayed signal could lead to nausea and headaches, and the user’s viewpoint is limited to one perspective.

In a cyber-physical model, the user is separate from the robot. The user interacts with a virtual copy of the robot and the environment. This requires much more data, and specialized spaces.

The CSAIL team’s system is halfway between these two methods. It solves the delay problem, since the user is constantly receiving visual feedback from the virtual world. It also solves the the cyber-physical issue of being distinct from the robot: Once a user puts on the headset and logs into the system, they’ll feel as if they’re inside Baxter’s head.

The system mimics the homunculus model of the mind — the idea that there’s a small human inside our brains controlling our actions, viewing the images we see, and understanding them for us. While it’s a peculiar idea for humans, for robots it fits: Inside the robot is a human in a virtual control room, seeing through its eyes and controlling its actions.

Using Oculus’ controllers, users can interact with controls that appear in the virtual space to open and close the hand grippers to pick up, move, and retrieve items. A user can plan movements based on the distance between the arm’s location marker and their hand while looking at the live display of the arm.

To make these movements possible, the human’s space is mapped into the virtual space, and the virtual space is then mapped into the robot space to provide a sense of co-location.

The system is also more flexible compared to previous systems that require many resources. Other systems might extract 2-D information from each camera, build out a full 3-D model of the environment, and then process and redisplay the data. In contrast, the CSAIL team’s approach bypasses all of that by simply taking the 2-D images that are displayed to each eye. (The human brain does the rest by automatically inferring the 3-D information.) 

To test the system, the team first teleoperated Baxter to do simple tasks like picking up screws or stapling wires. They then had the test users teleoperate the robot to pick up and stack blocks.

Users successfully completed the tasks at a much higher rate compared to the direct model. Unsurprisingly, users with gaming experience had much more ease with the system.

Tested against current state-of-the-art systems, CSAIL’s system was better at grasping objects 95 percent of the time and 57 percent faster at doing tasks. The team also showed that the system could pilot the robot from hundreds of miles away; testing included controling Baxter at MIT from a hotel’s wireless network in Washington.

“This contribution represents a major milestone in the effort to connect the user with the robot’s space in an intuitive, natural, and effective manner.” says Oussama Khatib, a computer science professor at Stanford University who was not involved in the paper.

The team eventually wants to focus on making the system more scalable, with many users and different types of robots that can be compatible with current automation technologies.

The project was funded, in part, by the Boeing Company and the National Science Foundation.

From butterflies that sprout wings to hermit crabs that switch their shells, many animals must adapt their exterior features in order to survive. While humans don’t undergo that kind of metamorphosis, we often try to create functional objects that are similarly adaptive — including our robots.

Despite what you might have seen in “Transformers” movies, though, today’s robots are still pretty inflexible. Each of their parts usually has a fixed structure and a single defined purpose, making it difficult for them to perform a wide variety of actions.

Researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) are aiming to change that with a new shape-shifting robot that’s something of a superhero: It can transform itself with different “outfits” that allow it to perform different tasks.

Dubbed “Primer,” the cube-shaped robot can be controlled via magnets to make it walk, roll, sail, and glide. It carries out these actions by wearing different exoskeletons, which start out as sheets of plastic that fold into specific shapes when heated. After Primer finishes its task, it can shed its “skin” by immersing itself in water, which dissolves the exoskeleton.

“If we want robots to help us do things, it’s not very efficient to have a different one for each task,” says Daniela Rus, CSAIL director and principal investigator on the project. “With this metamorphosis-inspired approach, we can extend the capabilities of a single robot by giving it different ‘accessories’ to use in different situations.”

Primer’s various forms have a range of advantages. For example, “Wheel-bot” has wheels that allow it to move twice as fast as “Walk-bot.” “Boat-bot” can float on water and carry nearly twice its weight. “Glider-bot” can soar across longer distances, which could be useful for deploying robots or switching environments.

Primer can even wear multiple outfits at once, like a Russian nesting doll. It can add one exoskeleton to become “Walk-bot,” and then interface with another, larger exoskeleton that allows it to carry objects and move two body lengths per second. To deploy the second exoskeleton, “Walk-bot” steps onto the sheet, which then blankets the bot with its four self-folding arms.

“Imagine future applications for space exploration, where you could send a single robot with a stack of exoskeletons to Mars,” says postdoc Shuguang Li, one of the co-authors of the study. “The robot could then perform different tasks by wearing different ‘outfits.’”

The project was led by Rus and Shuhei Miyashita, a former CSAIL postdoc who is now director of the Microrobotics Group at the University of York. Their co-authors include Li and graduate student Steven Guitron. An article about the work appears in the journal Science Robotics on Sept. 27.

Robot metamorphosis

Primer builds on several previous projects from Rus’ team, including magnetic blocks that can assemble themselves into different shapes and centimeter-long microrobots that can be precisely customized from sheets of plastic.

While robots that can change their form or function have been developed at larger sizes, it’s generally been difficult to build such structures at much smaller scales.

“This work represents an advance over the authors’ previous work in that they have now demonstrated a scheme that allows for the creation of five different functionalities,” says Eric Diller, a microrobotics expert and assistant professor of mechanical engineering at the University of Toronto, who was not involved in the paper. “Previous work at most shifted between only two functionalities, such as ‘open’ or ‘closed’ shapes.”

The team outlines many potential applications for robots that can perform multiple actions with just a quick costume change. For example, say some equipment needs to be moved across a stream. A single robot with multiple exoskeletons could potentially sail across the stream and then carry objects on the other side.

“Our approach shows that origami-inspired manufacturing allows us to have robotic components that are versatile, accessible, and reusable,” says Rus, the Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science at MIT.

Designed in a matter of hours, the exoskeletons fold into shape after being heated for just a few seconds, suggesting a new approach to rapid fabrication of robots.

“I could envision devices like these being used in ‘microfactories’ where prefabricated parts and tools would enable a single microrobot to do many complex tasks on demand,” Diller says.

As a next step, the team plans to explore giving the robots an even wider range of capabilities, from driving through water and burrowing in sand to camouflaging their color. Guitron pictures a future robotics community that shares open-source designs for parts much the way 3-D-printing enthusiasts trade ideas on sites such as Thingiverse.

“I can imagine one day being able to customize robots with different arms and appendages,” says Rus. “Why update a whole robot when you can just update one part of it?”

This project was supported, in part, by the National Science Foundation.

Researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have developed a new system that allows programmers to transplant code from one program into another. The programmer can select the code from one program and an insertion point in a second program, and the system will automatically make modifications necessary — such as changing variable names — to integrate the code into its new context.

Crucially, the system is able to translate between “data representations” used by the donor and recipient programs. An image-processing program, for instance, needs to be able to handle files in a range of formats, such as jpeg, tiff, or png. But internally, it will represent all such images using a single standardized scheme. Different programs, however, may use different internal schemes. The CSAIL researchers’ system automatically maps the donor program’s scheme onto that of the recipient, to import code seamlessly.

The researchers presented the new system, dubbed CodeCarbonCopy, at the Association for Computing Machinery’s Symposium on the Foundations of Software Engineering.

“CodeCarbonCopy enables one of the holy grails of software engineering: automatic code reuse,” says Stelios Sidiroglou-Douskos, a research scientist at CSAIL and first author on the paper. “It’s another step toward automating the human away from the development cycle. Our view is that perhaps we have written most of the software that we’ll ever need — we now just need to reuse it.”

The researchers conducted eight experiments in which they used CodeCarbonCopy to transplant code between six popular open-source image-processing programs. Seven of the eight transplants were successful, with the recipient program properly executing the new functionality.

Joining Sidiroglou-Douskos on the paper are Martin Rinard, a professor of electrical engineering and computer science; Fan Long, an MIT graduate student in electrical engineering and computer science; and Eric Lahtinen and Anthony Eden, who were contract programmers at MIT when the work was done.

Mutatis mutandis

With CodeCarbonCopy, the first step in transplanting code from one program to another is to feed both of them the same input file. The system then compares how the two programs process the file.

If, for instance, the donor program performs a series of operations on a particular piece of data and loads the result into a variable named “mem_clip->width,” and the recipient performs the same operations on the same piece of data and loads the result into a variable named “picture.width,” the system will infer that the variables are playing the same roles in their respective programs.

Once it has identified correspondences between variables, CodeCarbonCopy presents them to the user. It also presents all the variables in the donor for which it could not find matches in the recipient, together with those variables’ initial definitions. Frequently, those variables are playing some role in the donor that’s irrelevant to the recipient. The user can flag those variables as unnecessary, and CodeCarbonCopy will automatically excise any operations that make use of them from the transplanted code.

New order

To map the data representations from one program onto those of the other, CodeCarbonCopy looks at the precise values that both programs store in memory. Every pixel in a digital image, for instance, is governed by three color values: red, green, and blue. Some programs, however, store those triplets of values in the order red, green, blue, and others store them in the order blue, green, red.

If CodeCarbonCopy finds a systematic relationship between the values stored by one program and those stored by the other, it generates a set of operations for translating between representations.

CodeCarbonCopy works well with file formats, such as images, whose data is rigidly organized, and with programs, such as image processors, that store data representations in arrays, which are essentially rows of identically sized memory units. In ongoing work, the researchers are looking to generalize their approach to file formats that permit more flexible data organization and programs that use data structures other than arrays, such as trees or linked lists.

“In general, code quoting is where a lot of problems in software come from,” says Vitaly Shmatikov, a professor of computer science at Cornell Tech, a joint academic venture between Cornell University and Israel’s Technion. “Both bugs and security vulnerabilities — a lot of them occur when there is functionality in one place, and someone tries to either cut and paste or reimplement this functionality in another place. They make a small mistake, and that’s how things break. So having an automated way of moving code from one place to another would be a huge, huge deal, and this is a very solid step toward having it.”

“Recognizing irrelevant code that’s not important for the functionality that they’re quoting, that’s another technical innovation that’s important,” Shmatikov adds. “That’s the kind of thing that was an obstacle for a lot of previous approaches — that you know the right code is there, but it’s mixed up with a lot of code that is not relevant to what you’re trying to do. So being able to separate that out is a fairly significant technical contribution.”

As 3-D printing has become a mainstream technology, industry and academic researchers have been investigating printable structures that will fold themselves into useful three-dimensional shapes when heated or immersed in water.

In a paper appearing in the American Chemical Society’s journal Applied Materials and Interfaces, researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) and colleagues report something new: a printable structure that begins to fold itself up as soon as it’s peeled off the printing platform.

One of the big advantages of devices that self-fold without any outside stimulus, the researchers say, is that they can involve a wider range of materials and more delicate structures.

“If you want to add printed electronics, you’re generally going to be using some organic materials, because a majority of printed electronics rely on them,” says Subramanian Sundaram, an MIT graduate student in electrical engineering and computer science and first author on the paper. “These materials are often very, very sensitive to moisture and temperature. So if you have these electronics and parts, and you want to initiate folds in them, you wouldn’t want to dunk them in water or heat them, because then your electronics are going to degrade.”

To illustrate this idea, the researchers built a prototype self-folding printable device that includes electrical leads and a polymer “pixel” that changes from transparent to opaque when a voltage is applied to it. The device, which is a variation on the “printable goldbug” that Sundaram and his colleagues announced earlier this year, starts out looking something like the letter “H.” But each of the legs of the H folds itself in two different directions, producing a tabletop shape.

The researchers also built several different versions of the same basic hinge design, which show that they can control the precise angle at which a joint folds. In tests, they forcibly straightened the hinges by attaching them to a weight, but when the weight was removed, the hinges resumed their original folds.

In the short term, the technique could enable the custom manufacture of sensors, displays, or antennas whose functionality depends on their three-dimensional shape. Longer term, the researchers envision the possibility of printable robots.

Sundaram is joined on the paper by his advisor, Wojciech Matusik, an associate professor of electrical engineering and computer science (EECS) at MIT; Marc Baldo, also an associate professor of EECS, who specializes in organic electronics; David Kim, a technical assistant in Matusik’s Computational Fabrication Group; and Ryan Hayward, a professor of polymer science and engineering at the University of Massachusetts at Amherst.

This clip shows an example of an accelerated fold. (Image: Tom Buehler/CSAIL)

Stress relief

The key to the researchers’ design is a new printer-ink material that expands after it solidifies, which is unusual. Most printer-ink materials contract slightly as they solidify, a technical limitation that designers frequently have to work around.

Printed devices are built up in layers, and in their prototypes the MIT researchers deposit their expanding material at precise locations in either the top or bottom few layers. The bottom layer adheres slightly to the printer platform, and that adhesion is enough to hold the device flat as the layers are built up. But as soon as the finished device is peeled off the platform, the joints made from the new material begin to expand, bending the device in the opposite direction.

Like many technological breakthroughs, the CSAIL researchers’ discovery of the material was an accident. Most of the printer materials used by Matusik’s Computational Fabrication Group are combinations of polymers, long molecules that consist of chainlike repetitions of single molecular components, or monomers. Mixing these components is one method for creating printer inks with specific physical properties.

While trying to develop an ink that yielded more flexible printed components, the CSAIL researchers inadvertently hit upon one that expanded slightly after it hardened. They immediately recognized the potential utility of expanding polymers and began experimenting with modifications of the mixture, until they arrived at a recipe that let them build joints that would expand enough to fold a printed device in half.

Whys and wherefores

Hayward’s contribution to the paper was to help the MIT team explain the material’s expansion. The ink that produces the most forceful expansion includes several long molecular chains and one much shorter chain, made up of the monomer isooctyl acrylate. When a layer of the ink is exposed to ultraviolet light — or “cured,” a process commonly used in 3-D printing to harden materials deposited as liquids — the long chains connect to each other, producing a rigid thicket of tangled molecules.

When another layer of the material is deposited on top of the first, the small chains of isooctyl acrylate in the top, liquid layer sink down into the lower, more rigid layer. There, they interact with the longer chains to exert an expansive force, which the adhesion to the printing platform temporarily resists.

The researchers hope that a better theoretical understanding of the reason for the material’s expansion will enable them to design material tailored to specific applications — including materials that resist the 1–3 percent contraction typical of many printed polymers after curing.

“This work is exciting because it provides a way to create functional electronics on 3-D objects,” says Michael Dickey, a professor of chemical engineering at North Carolina State University. “Typically, electronic processing is done in a planar, 2-D fashion and thus needs a flat surface. The work here provides a route to create electronics using more conventional planar techniques on a 2-D surface and then transform them into a 3-D shape, while retaining the function of the electronics. The transformation happens by a clever trick to build stress into the materials during printing.”

This summer, a survey released by the American Automobile Association showed that 78 percent of Americans feared riding in a self-driving car, with just 19 percent trusting the technology. What might it take to alter public opinion on the issue? Iyad Rahwan, the AT&T Career Development Professor in the MIT Media Lab, has studied the issue at length, and, along with Jean-Francois Bonnefon of the Toulouse School of Economics and Azim Shariff of the University of California at Irvine, has authored a new commentary on the subject, titled, “Psychological roadblocks to the adoption of self-driving vehicles,” published today in Nature Human Behavior. Rahwan spoke to MIT News about the hurdles automakers face if they want greater public buy-in for autonomous vehicles.  

Q: Your new paper states that when it comes to autonomous vehicles, trust “will determine how widely they are adopted by consumers, and how tolerated they are by everyone else.” Why is this?

A: It’s a new kind of agent in the world. We’ve always built tools and had to trust that technology will function in the way it was intended. We’ve had to trust that the materials are reliable and don’t have health hazards, and that there are consumer protection entities that promote the interests of consumers. But these are passive products that we choose to use. For the first time in history we are building objects that are proactive and have autonomy and are even adaptive. They are learning behaviors that may be different from the ones they were originally programmed for. We don’t really know how to get people to trust such entities, because humans don’t have mental models of what these entities are, what they’re capable of, how they learn.

Before we can trust machines like autonomous vehicles, we have a number of challenges. The first is technical: the challenge of building an AI [artificial intelligence] system that can drive a car. The second is legal and regulatory: Who is liable for different kinds of faults? A third class of challenges is psychological. Unless people are comfortable putting their lives in the hands of AI, then none of this will matter. People won’t buy the product, the economics won’t work, and that’s the end of the story. What we’re trying to highlight in this paper is that these psychological challenges have to be taken seriously, even if [people] are irrational in the way they assess risk, even if the technology is safe and the legal framework is reliable.

Q: What are the specific psychological issues people have with autonomous vehicles?

A: We classify three psychological challenges that we think are fairly big. One of them is dilemmas: A lot of people are concerned about how autonomous vehicles will resolve ethical dilemmas. How will they decide, for example, whether to prioritize safety for the passenger or safety for pedestrians? Should this influence the way in which the car makes a decision about relative risk? And what we’re finding is that people have an idea about how to solve this dilemma: The car should just minimize harm. But the problem is that people are not willing to buy such cars, because they want to buy cars that will always prioritize themselves.

A second one is that people don’t always reason about risk in an unbiased way. People may overplay the risk of dying in a car crash caused by an autonomous vehicle even if autonomous vehicles are, on the average, safer. We’ve seen this kind of overreaction in other fields. Many people are afraid of flying even though you’re incredibly less likely to die from a plane crash than a car crash. So people don’t always reason about risk.

The third class of psychological challenges is this idea that we don’t always have transparency about what the car is thinking and why it’s doing what it’s doing. The carmaker has better knowledge of what the car thinks and how it behaves … which makes it more difficult for people to predict the behavior of autonomous vehicles, which can also dimish trust. One of the preconditions of trust is predictability: If I can trust that you will behave in a particular way, I can behave according to that expectation.

Q: In the paper you state that autonomous vehicles are better depicted “as being perfected, not as perfect.” In essence, is that your advice to the auto industry?

A: Yes, I think setting up very high expectations can be a recipe for disaster, because if you overpromise and underdeliver, you get in trouble. That is not to say that we should underpromise. We should just be a bit realistic about what we promise. If the promise is an improvement on the current status quo, that is, a reduction in risk to everyone, both pedestrians as well as passengers in cars, that’s an admirable goal. Even if we achieve it in a small way, that’s already progress that we should take seriously. I think being transparent about that, and being transparent about the progress being made toward that goal, is crucial.

IBM and MIT today announced that IBM plans to make a 10-year, $240 million investment to create the MIT–IBM Watson AI Lab in partnership with MIT. The lab will carry out fundamental artificial intelligence (AI) research and seek to propel scientific breakthroughs that unlock the potential of AI. The collaboration aims to advance AI hardware, software, and algorithms related to deep learning and other areas; increase AI’s impact on industries, such as health care and cybersecurity; and explore the economic and ethical implications of AI on society. IBM’s $240 million investment in the lab will support research by IBM and MIT scientists.

The new lab will be one of the largest long-term university-industry AI collaborations to date, mobilizing the talent of more than 100 AI scientists, professors, and students to pursue joint research at IBM’s Research Lab in Cambridge, Massachusetts — co-located with the IBM Watson Health and IBM Security headquarters in Kendall Square — and on the neighboring MIT campus.

The lab will be co-chaired by Dario Gil, IBM Research VP of AI and IBM Q, and Anantha P. Chandrakasan, dean of MIT’s School of Engineering. (Read a related Q&A with Chandrakasan.) IBM and MIT plan to issue a call for proposals to MIT researchers and IBM scientists to submit their ideas for joint research to push the boundaries in AI science and technology in several areas, including:

• AI algorithms: Developing advanced algorithms to expand capabilities in machine learning and reasoning. Researchers will create AI systems that move beyond specialized tasks to tackle more complex problems and benefit from robust, continuous learning. Researchers will invent new algorithms that can not only leverage big data when available, but also learn from limited data to augment human intelligence.

• Physics of AI: Investigating new AI hardware materials, devices, and architectures that will support future analog computational approaches to AI model training and deployment, as well as the intersection of quantum computing and machine learning. The latter involves using AI to help characterize and improve quantum devices, and researching the use of quantum computing to optimize and speed up machine-learning algorithms and other AI applications.

• Application of AI to industries: Given its location in IBM Watson Health and IBM Security headquarters in Kendall Square, a global hub of biomedical innovation, the lab will develop new applications of AI for professional use, including fields such as health care and cybersecurity. The collaboration will explore the use of AI in areas such as the security and privacy of medical data, personalization of health care, image analysis, and the optimum treatment paths for specific patients.

• Advancing shared prosperity through AI: The MIT–IBM Watson AI Lab will explore how AI can deliver economic and societal benefits to a broader range of people, nations, and enterprises. The lab will study the economic implications of AI and investigate how AI can improve prosperity and help individuals achieve more in their lives.

In addition to IBM’s plan to produce innovations that advance the frontiers of AI, a distinct objective of the new lab is to encourage MIT faculty and students to launch companies that will focus on commercializing AI inventions and technologies that are developed at the lab. The lab’s scientists also will publish their work, contribute to the release of open source material, and foster an adherence to the ethical application of AI.

“The field of artificial intelligence has experienced incredible growth and progress over the past decade. Yet today’s AI systems, as remarkable as they are, will require new innovations to tackle increasingly difficult real-world problems to improve our work and lives,” says John Kelly III, IBM senior vice president, Cognitive Solutions and Research. “The extremely broad and deep technical capabilities and talent at MIT and IBM are unmatched, and will lead the field of AI for at least the next decade.”

“I am delighted by this new collaboration,” MIT President L. Rafael Reif says. “True breakthroughs are often the result of fresh thinking inspired by new kinds of research teams. The combined MIT and IBM talent dedicated to this new effort will bring formidable power to a field with staggering potential to advance knowledge and help solve important challenges.”

Both MIT and IBM have been pioneers in artificial intelligence research, and the new AI lab builds on a decades-long research relationship between the two. In 2016, IBM Research announced a multiyear collaboration with MIT’s Department of Brain and Cognitive Sciences to advance the scientific field of machine vision, a core aspect of artificial intelligence. The collaboration has brought together leading brain, cognitive, and computer scientists to conduct research in the field of unsupervised machine understanding of audio-visual streams of data, using insights from next-generation models of the brain to inform advances in machine vision. In addition, IBM and the Broad Institute of MIT and Harvard have established a five-year, $50 million research collaboration on AI and genomics.

MIT researchers were among those who helped coin and popularize the very phrase “artificial intelligence” in the 1950s. MIT pushed several major advances in the subsequent decades, from neural networks to data encryption to quantum computing to crowdsourcing. Marvin Minsky, a founder of the discipline, collaborated on building the first artificial neural network and he, along with Seymour Papert, advanced learning algorithms. Currently, the Computer Science and Artificial Intelligence Laboratory, the Media Lab, the Department of Brain and Cognitive Sciences, and the MIT Institute for Data, Systems, and Society serve as connected hubs for AI and related research at MIT.

For more than 20 years, IBM has explored the application of AI across many areas and industries. IBM researchers invented and built Watson, which is a cloud-based AI platform being used by businesses, developers, and universities to fight cancer, improve classroom learning, minimize pollution, enhance agriculture and oil and gas exploration, better manage financial investments, and much more. Today, IBM scientists across the globe are working on fundamental advances in AI algorithms, science and technology that will pave the way for the next generation of artificially intelligent systems.

For information about employment opportunities with IBM at the new AI Lab, please visit MITIBMWatsonAILab.mit.edu.

by Dara Farhadi

While working for the global management consulting company Accenture, Gregory Falco discovered just how vulnerable the technologies underlying smart cities and the “internet of things” — everyday devices that are connected to the internet or a network — are to cyberterrorism attacks.

“What happened was, I was telling sheiks and government officials all around the world about how amazing the internet of things is and how it’s going to solve all their problems and solve sustainability issues and social problems,” Falco says. “And then they asked me, ‘Is it secure?’ I looked at the security guys and they said, ‘There’s no problem.’ And then I looked under the hood myself, and there was nothing going on there.”

Falco is currently transitioning into the third and final year of his PhD within the Department of Urban Studies and Planning (DUSP). Currently, his is carrying out his research at the Computer Science and Artificial Intelligence Laboratory (CSAIL). His focus is on cybersecurity for urban critical infrastructure, and the internet of things, or IoT, is at the center of his work. A washing machine, for example, that is connected to an app on its owner’s smartphone is considered part of the IoT. There are billions of IoT devices that don’t have traditional security software because they’re built with small amounts of memory and low-power processors. This makes these devices susceptible to cyberattacks and may provide a gate for hackers to breach other devices on the same network.

Falco’s concentration is on industrial controls and embedded systems such as automatic switches found in subway systems.

“If someone decides to figure out how to access a switch by hacking another access point that is communicating with that switch, then that subway is not going to stop, and people are going to die,” Falco says. “We rely on these systems for our life functions — critical infrastructure like electric grids, water grids, or transportation systems, but also our health care systems. Insulin pumps, for example, are now connected to your smartphone.”

Citing real-world examples, Falco notes that Russian hackers were able to take down the Ukrainian capital city’s electric grid, and that Iranian hackers interfered with the computer-guided controls of a small dam in Rye Brook, New York.

Falco aims to help combat potential cyberattacks through his research. One arm of his dissertation, which he is working on with renown negotiation Professor Lawrence Susskind, is aimed at conflict negotiation, and looks at how best to negotiate with cyberterrorists. Also, with CSAIL Principal Research Scientist Howard Shrobe, Falco seeks to determine the possibility of predicting which control-systems vulnerabilities could be exploited in critical urban infrastructure. The final branch of Falco’s dissertation is in collaboration with NASA’s Jet Propulsion Laboratory. He has secured a contract to develop an artificial intelligence-powered automated attack generator that can identify all the possible ways someone could hack and destroy NASA’s systems.

“What I really intend to do for my PhD is something that is actionable to the communities I’m working with,” Falco says. “I don’t want to publish something in a book that will sit on a shelf where nobody would read it.”

“Not science fiction anymore”

Falco’s battle against cyberterrorism has also lead him to co-found NeuroMesh, a startup dedicated to protecting IoT devices by using the same techniques hackers use.

“The concept of my startup is, ‘Let’s use hacker tools to defeat hackers,’” Falco says. “If you don’t know how to break it, you don’t know how to fix it.”

One tool hackers use is called a botnet. Once botnets get on a device, they often kill off other malware on the device so that they use all the processing power on the device for themselves. Botnets also play “king of the hill” on the device, and don’t let other botnets latch on.

NeuroMesh uses a botnet’s features against itself to create a good botnet. By re-engineering the botnet, programmers can use them to defeat any kind of malware that comes onto a device.

“The benefit is also that when you look at securing IoT devices with low memory and low processing power, it’s impossible to put any security on them, but these botnets have no problem getting on there because they are so small,” Falco says.

Much like a vaccine protects against diseases, NeuroMesh applies a cyber vaccine to protect industrial devices from cyberattacks. And, by leveraging the bitcoin blockchain to update devices, NeuroMesh further fortifies the security system to block other malware from attacking vital IoT devices.

Recently, Falco and his team pitched their botnet vaccine at MIT’s $100K Accelerate competition and placed second. Falco’s infant son was in the audience while Falco was presenting how NeuroMesh’s technology could secure a baby monitor, as an example, from being hacked. The startup advanced to MIT’s prestigious 100K Launch startup competition, where they finished among the top eight competitors. NeuroMesh is now further developing its technology with the help of a grant from the Department of Energy, working with Stuart Madnick, who is the John Norris Maguire Professor at MIT, and Michael Siegel, a principal research scientist at MIT’s Sloan School of Management.

“Enemies are here. They are on our turf and in our wires. It’s not science fiction anymore,” Falco says. “We’re protecting against this. That’s what NeuroMesh is meant to do.”  

The human tornado

Falco’s abundant energy has led his family to call him “the tornado.”

“One-fourth of my mind is on my startup, one-fourth on finishing my dissertation, and other half is on my 11-month-old because he comes with me when my wife works,” Falco says. “He comes to all our venture capital meetings and my presentations. He’s always around and he’s generally very good.”

As a high school student, Falco’s energy and excitement for engineering drove him to discover a new physics wave theory. Applying this to the tennis racket, he invented a new, control-enhanced method of stringing, with which he won various science competitions (and tennis matches). He used this knowledge to start a small business for stringing rackets. The thrill of business took him on a path to Cornell University’s School of Hotel Administration. After graduating early, Falco transitioned into the field of sustainability technology and energy systems, and returned to his engineering roots by earning his LEED AP (Leadership in Energy and Environmental Design) accreditation and a master’s degree in sustainability management from Columbia University.

His excitement followed him to Accenture, where he founded the smart cities division and eventually learned about the vulnerability of IoT devices. For the past three years, Falco has also been sharing his newfound knowledge about sustainability and computer science as an adjunct professor at Columbia University.

“My challenge is always to find these interdisciplinary holes because my background is so messed up. You can’t say, this guy is a computer scientist or he’s a business person or an environmental scientist because I’m all over the place,” he says.

That’s part of the reason why Falco enjoys taking care of his son, Milo, so much.

“He’s the most awesome thing ever. I see him learning and it’s really amazing,” Falco says. “Spending so much time with him is very fun. He does things that my wife gets frustrated at because he’s a ball of energy and all over the place — just like me.”

Recording electrical signals from inside a neuron in the living brain can reveal a great deal of information about that neuron’s function and how it coordinates with other cells in the brain. However, performing this kind of recording is extremely difficult, so only a handful of neuroscience labs around the world do it.

To make this technique more widely available, MIT engineers have now devised a way to automate the process, using a computer algorithm that analyzes microscope images and guides a robotic arm to the target cell.

This technology could allow more scientists to study single neurons and learn how they interact with other cells to enable cognition, sensory perception, and other brain functions. Researchers could also use it to learn more about how neural circuits are affected by brain disorders.

“Knowing how neurons communicate is fundamental to basic and clinical neuroscience. Our hope is this technology will allow you to look at what’s happening inside a cell, in terms of neural computation, or in a disease state,” says Ed Boyden, an associate professor of biological engineering and brain and cognitive sciences at MIT, and a member of MIT’s Media Lab and McGovern Institute for Brain Research.

Boyden is the senior author of the paper, which appears in the Aug. 30 issue of Neuron. The paper’s lead author is MIT graduate student Ho-Jun Suk.

Precision guidance

For more than 30 years, neuroscientists have been using a technique known as patch clamping to record the electrical activity of cells. This method, which involves bringing a tiny, hollow glass pipette in contact with the cell membrane of a neuron, then opening up a small pore in the membrane, usually takes a graduate student or postdoc several months to learn. Learning to perform this on neurons in the living mammalian brain is even more difficult.

There are two types of patch clamping: a “blind” (not image-guided) method, which is limited because researchers cannot see where the cells are and can only record from whatever cell the pipette encounters first, and an image-guided version that allows a specific cell to be targeted.

Five years ago, Boyden and colleagues at MIT and Georgia Tech, including co-author Craig Forest, devised a way to automate the blind version of patch clamping. They created a computer algorithm that could guide the pipette to a cell based on measurements of a property called electrical impedance — which reflects how difficult it is for electricity to flow out of the pipette. If there are no cells around, electricity flows and impedance is low. When the tip hits a cell, electricity can’t flow as well and impedance goes up.

Once the pipette detects a cell, it can stop moving instantly, preventing it from poking through the membrane. A vacuum pump then applies suction to form a seal with the cell’s membrane. Then, the electrode can break through the membrane to record the cell’s internal electrical activity.

The researchers achieved very high accuracy using this technique, but it still could not be used to target a specific cell. For most studies, neuroscientists have a particular cell type they would like to learn about, Boyden says.

“It might be a cell that is compromised in autism, or is altered in schizophrenia, or a cell that is active when a memory is stored. That’s the cell that you want to know about,” he says. “You don’t want to patch a thousand cells until you find the one that is interesting.”

To enable this kind of precise targeting, the researchers set out to automate image-guided patch clamping. This technique is difficult to perform manually because, although the scientist can see the target neuron and the pipette through a microscope, he or she must compensate for the fact that nearby cells will move as the pipette enters the brain.

“It’s almost like trying to hit a moving target inside the brain, which is a delicate tissue,” Suk says. “For machines it’s easier because they can keep track of where the cell is, they can automatically move the focus of the microscope, and they can automatically move the pipette.”

By combining several imaging processing techniques, the researchers came up with an algorithm that guides the pipette to within about 25 microns of the target cell. At that point, the system begins to rely on a combination of imagery and impedance, which is more accurate at detecting contact between the pipette and the target cell than either signal alone.

The researchers imaged the cells with two-photon microscopy, a commonly used technique that uses a pulsed laser to send infrared light into the brain, lighting up cells that have been engineered to express a fluorescent protein.

Using this automated approach, the researchers were able to successfully target and record from two types of cells — a class of interneurons, which relay messages between other neurons, and a set of excitatory neurons known as pyramidal cells. They achieved a success rate of about 20 percent, which is comparable to the performance of highly trained scientists performing the process manually.

Unraveling circuits

This technology paves the way for in-depth studies of the behavior of specific neurons, which could shed light on both their normal functions and how they go awry in diseases such as Alzheimer’s or schizophrenia. For example, the interneurons that the researchers studied in this paper have been previously linked with Alzheimer’s. In a recent study of mice, led by Li-Huei Tsai, director of MIT’s Picower Institute for Learning and Memory, and conducted in collaboration with Boyden, it was reported that inducing a specific frequency of brain wave oscillation in interneurons in the hippocampus could help to clear amyloid plaques similar to those found in Alzheimer’s patients.

“You really would love to know what’s happening in those cells,” Boyden says. “Are they signaling to specific downstream cells, which then contribute to the therapeutic result? The brain is a circuit, and to understand how a circuit works, you have to be able to monitor the components of the circuit while they are in action.”

This technique could also enable studies of fundamental questions in neuroscience, such as how individual neurons interact with each other as the brain makes a decision or recalls a memory.

Bernardo Sabatini, a professor of neurobiology at Harvard Medical School, says he is interested in adapting this technique to use in his lab, where students spend a great deal of time recording electrical activity from neurons growing in a lab dish.

“It’s silly to have amazingly intelligent students doing tedious tasks that could be done by robots,” says Sabatini, who was not involved in this study. “I would be happy to have robots do more of the experimentation so we can focus on the design and interpretation of the experiments.”

To help other labs adopt the new technology, the researchers plan to put the details of their approach on their web site, autopatcher.org.

Other co-authors include Ingrid van Welie, Suhasa Kodandaramaiah, and Brian Allen. The research was funded by Jeremy and Joyce Wertheimer, the National Institutes of Health (including the NIH Single Cell Initiative and the NIH Director’s Pioneer Award), the HHMI-Simons Faculty Scholars Program, and the New York Stem Cell Foundation-Robertson Award.

by Adam Conner-Simons & Rachel Gordon

Despite what you might see in movies, today’s robots are still very limited in what they can do. They can be great for many repetitive tasks, but their inability to understand the nuances of human language makes them mostly useless for more complicated requests.

For example, if you put a specific tool in a toolbox and ask a robot to “pick it up,” it would be completely lost. Picking it up means being able to see and identify objects, understand commands, recognize that the “it” in question is the tool you put down, go back in time to remember the moment when you put down the tool, and distinguish the tool you put down from other ones of similar shapes and sizes.

Recently researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have gotten closer to making this type of request easier: In a new paper, they present an Alexa-like system that allows robots to understand a wide range of commands that require contextual knowledge about objects and their environments. They’ve dubbed the system “ComText,” for “commands in context.”

The toolbox situation above was among the types of tasks that ComText can handle. If you tell the system that “the tool I put down is my tool,” it adds that fact to its knowledge base. You can then update the robot with more information about other objects and have it execute a range of tasks like picking up different sets of objects based on different commands.

“Where humans understand the world as a collection of objects and people and abstract concepts, machines view it as pixels, point-clouds, and 3-D maps generated from sensors,” says CSAIL postdoc Rohan Paul, one of the lead authors of the paper. “This semantic gap means that, for robots to understand what we want them to do, they need a much richer representation of what we do and say.”

The team tested ComText on Baxter, a two-armed humanoid robot developed for Rethink Robotics by former CSAIL director Rodney Brooks.

The project was co-led by research scientist Andrei Barbu, alongside research scientist Sue Felshin, senior research scientist Boris Katz, and Professor Nicholas Roy. They presented the paper at last week’s International Joint Conference on Artificial Intelligence (IJCAI) in Australia.

How it works

Things like dates, birthdays, and facts are forms of “declarative memory.” There are two kinds of declarative memory: semantic memory, which is based on general facts like the “sky is blue,” and episodic memory, which is based on personal facts, like remembering what happened at a party.

Most approaches to robot learning have focused only on semantic memory, which obviously leaves a big knowledge gap about events or facts that may be relevant context for future actions. ComText, meanwhile, can observe a range of visuals and natural language to glean “episodic memory” about an object’s size, shape, position, type and even if it belongs to somebody. From this knowledge base, it can then reason, infer meaning and respond to commands.

“The main contribution is this idea that robots should have different kinds of memory, just like people,” says Barbu. “We have the first mathematical formulation to address this issue, and we’re exploring how these two types of memory play and work off of each other.”

With ComText, Baxter was successful in executing the right command about 90 percent of the time. In the future, the team hopes to enable robots to understand more complicated information, such as multi-step commands, the intent of actions, and using properties about objects to interact with them more naturally.

For example, if you tell a robot that one box on a table has crackers, and one box has sugar, and then ask the robot to “pick up the snack,” the hope is that the robot could deduce that sugar is a raw material and therefore unlikely to be somebody’s “snack.”

By creating much less constrained interactions, this line of research could enable better communications for a range of robotic systems, from self-driving cars to household helpers.

“This work is a nice step towards building robots that can interact much more naturally with people,” says Luke Zettlemoyer, an associate professor of computer science at the University of Washington who was not involved in the research. “In particular, it will help robots better understand the names that are used to identify objects in the world, and interpret instructions that use those names to better do what users ask.”

The work was funded, in part, by the Toyota Research Institute, the National Science Foundation, the Robotics Collaborative Technology Alliance of the U.S. Army, and the Air Force Research Laboratory.

Just as drivers observe the rules of the road, most pedestrians follow certain social codes when navigating a hallway or a crowded thoroughfare: Keep to the right, pass on the left, maintain a respectable berth, and be ready to weave or change course to avoid oncoming obstacles while keeping up a steady walking pace.

Now engineers at MIT have designed an autonomous robot with “socially aware navigation,” that can keep pace with foot traffic while observing these general codes of pedestrian conduct.

In drive tests performed inside MIT’s Stata Center, the robot, which resembles a knee-high kiosk on wheels, successfully avoided collisions while keeping up with the average flow of pedestrians. The researchers have detailed their robotic design in a paper that they will present at the IEEE Conference on Intelligent Robots and Systems in September.

“Socially aware navigation is a central capability for mobile robots operating in environments that require frequent interactions with pedestrians,” says Yu Fan “Steven” Chen, who led the work as a former MIT graduate student and is the lead author of the study. “For instance, small robots could operate on sidewalks for package and food delivery. Similarly, personal mobility devices could transport people in large, crowded spaces, such as shopping malls, airports, and hospitals.”

Chen’s co-authors are graduate student Michael Everett, former postdoc Miao Liu, and Jonathan How, the Richard Cockburn Maclaurin Professor of Aeronautics and Astronautics at MIT.

Social drive

In order for a robot to make its way autonomously through a heavily trafficked environment, it must solve four main challenges: localization (knowing where it is in the world), perception (recognizing its surroundings), motion planning (identifying the optimal path to a given destination), and control (physically executing its desired path).

Chen and his colleagues used standard approaches to solve the problems of localization and perception. For the latter, they outfitted the robot with off-the-shelf sensors, such as webcams, a depth sensor, and a high-resolution lidar sensor. For the problem of localization, they used open-source algorithms to map the robot’s environment and determine its position. To control the robot, they employed standard methods used to drive autonomous ground vehicles.

“The part of the field that we thought we needed to innovate on was motion planning,” Everett says. “Once you figure out where you are in the world, and know how to follow trajectories, which trajectories should you be following?”

That’s a tricky problem, particularly in pedestrian-heavy environments, where individual paths are often difficult to predict. As a solution, roboticists sometimes take a trajectory-based approach, in which they program a robot to compute an optimal path that accounts for everyone’s desired trajectories. These trajectories must be inferred from sensor data, because people don’t explicitly tell the robot where they are trying to go. 

“But this takes forever to compute. Your robot is just going to be parked, figuring out what to do next, and meanwhile the person’s already moved way past it before it decides ‘I should probably go to the right,’” Everett says. “So that approach is not very realistic, especially if you want to drive faster.”

Others have used faster, “reactive-based” approaches, in which a robot is programmed with a simple model, using geometry or physics, to quickly compute a path that avoids collisions.

The problem with reactive-based approaches, Everett says, is the unpredictability of human nature — people rarely stick to a straight, geometric path, but rather weave and wander, veering off to greet a friend or grab a coffee. In such an unpredictable environment, such robots tend to collide with people or look like they are being pushed around by avoiding people excessively.

 “The knock on robots in real situations is that they might be too cautious or aggressive,” Everett says. “People don’t find them to fit into the socially accepted rules, like giving people enough space or driving at acceptable speeds, and they get more in the way than they help.”

Training days

The team found a way around such limitations, enabling the robot to adapt to unpredictable pedestrian behavior while continuously moving with the flow and following typical social codes of pedestrian conduct.

They used reinforcement learning, a type of machine learning approach, in which they performed computer simulations to train a robot to take certain paths, given the speed and trajectory of other objects in the environment. The team also incorporated social norms into this offline training phase, in which they encouraged the robot in simulations to pass on the right, and penalized the robot when it passed on the left.

“We want it to be traveling naturally among people and not be intrusive,” Everett says. “We want it to be following the same rules as everyone else.”

The advantage to reinforcement learning is that the researchers can perform these training scenarios, which take extensive time and computing power, offline. Once the robot is trained in simulation, the researchers can program it to carry out the optimal paths, identified in the simulations, when the robot recognizes a similar scenario in the real world.

The researchers enabled the robot to assess its environment and adjust its path, every one-tenth of a second. In this way, the robot can continue rolling through a hallway at a typical walking speed of 1.2 meters per second, without pausing to reprogram its route.

“We’re not planning an entire path to the goal — it doesn’t make sense to do that anymore, especially if you’re assuming the world is changing,” Everett says. “We just look at what we see, choose a velocity, do that for a tenth of a second, then look at the world again, choose another velocity, and go again. This way, we think our robot looks more natural, and is anticipating what people are doing.”

Crowd control

Everett and his colleagues test-drove the robot in the busy, winding halls of MIT’s Stata Building, where the robot was able to drive autonomously for 20 minutes at a time. It rolled smoothly with the pedestrian flow, generally keeping to the right of hallways, occasionally passing people on the left, and avoiding any collisions.

“We wanted to bring it somewhere where people were doing their everyday things, going to class, getting food, and we showed we were pretty robust to all that,” Everett says. “One time there was even a tour group, and it perfectly avoided them.”

Everett says going forward, he plans to explore how robots might handle crowds in a pedestrian environment.

“Crowds have a different dynamic than individual people, and you may have to learn something totally different if you see five people walking together,” Everett says. “There may be a social rule of, ‘Don’t move through people, don’t split people up, treat them as one mass.’ That’s something we’re looking at in the future.”

This research was funded by Ford Motor Company.  

Even as robots become increasingly common, they remain incredibly difficult to make. From designing and modeling to fabricating and testing, the process is slow and costly: Even one small change can mean days or weeks of rethinking and revising important hardware.

But what if there were a way to let non-experts craft different robotic designs — in one sitting?

Researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) are getting closer to doing exactly that. In a new paper, they present a system called “Interactive Robogami” that lets you design a robot in minutes, and then 3-D print and assemble it in as little as four hours.
 

One of the key features of the system is that it allows designers to determine both the robot’s movement (“gait”) and shape (“geometry”), a capability that’s often separated in design systems.

“Designing robots usually requires expertise that only mechanical engineers and roboticists have,” says PhD student and co-lead author Adriana Schulz. “What’s exciting here is that we’ve created a tool that allows a casual user to design their own robot by giving them this expert knowledge.”

The paper, which is being published in the new issue of the International Journal of Robotics Research, was co-led by PhD graduate Cynthia Sung alongside MIT professors Wojciech Matusik and Daniela Rus.

The other co-authors include PhD student Andrew Spielberg, former master’s student Wei Zhao, former undergraduate Robin Cheng, and Columbia University professor Eitan Grinspun. (Sung is now an assistant professor at the University of Pennsylvania.)

How it works

3-D printing has transformed the way that people can turn ideas into real objects, allowing users to move away from more traditional manufacturing. Despite these developments, current design tools still have space and motion limitations, and there’s a steep learning curve to understanding the various nuances.

Interactive Robogami aims to be much more intuitive. It uses simulations and interactive feedback with algorithms for design composition, allowing users to focus on high-level conceptual design. Users can choose from a library of over 50 different bodies, wheels, legs, and “peripherals,” as well as a selection of different steps (“gaits”).

Importantly, the system is able to guarantee that a design is actually possible, analyzing factors such as speed and stability to make suggestions and ensure that, for example, the user doesn’t create a robot so top-heavy that it can’t move without tipping over.

Once designed, the robot is then fabricated. The team’s origami-inspired “3-D print and fold” technique involves printing the design as flat faces connected at joints, and then folding the design into the final shape, combining the most effective parts of 2-D and 3-D printing.  

“3-D printing lets you print complex, rigid structures, while 2-D fabrication gives you lightweight but strong structures that can be produced quickly,” Sung says. “By 3-D printing 2-D patterns, we can leverage these advantages to develop strong, complex designs with lightweight materials.”

Results

To test the system, the team used eight subjects who were given 20 minutes of training and asked to perform two tasks.

One task involved creating a mobile, stable car design in just 10 minutes. In a second task, users were given a robot design and asked to create a trajectory to navigate the robot through an obstacle course in the least amount of travel time.

The team fabricated a total of six robots, each of which took 10 to 15 minutes to design, three to seven hours to print and 30 to 90 minutes to assemble. The team found that their 3-D print-and-fold method reduced printing time by 73 percent and the amount of material used by 70 percent. The robots also demonstrated a wide range of movement, like using single legs to walk, using different step sequences, and using legs and wheels simultaneously.

“You can quickly design a robot that you can print out, and that will help you do these tasks very quickly, easily, and cheaply,” says Sung. “It’s lowering the barrier to have everyone design and create their own robots.”

Rus hopes people will be able to incorporate robots to help with everyday tasks, and that similar systems with rapid printing technologies will enable large-scale customization and production of robots.

“These tools enable new approaches to teaching computational thinking and creating,” says Rus. “Students can not only learn by coding and making their own robots, but by bringing to life conceptual ideas about what their robots can actually do.”

While the current version focuses on designs that can walk, the team hopes that in the future, the robots can take flight. Another goal is to have the user be able to go into the system and define the behavior of the robot in terms of tasks it can perform.

“This tool enables rapid exploration of dynamic robots at an early stage in the design process,” says Moritz Bächer, a research scientist and head of the computational design and manufacturing group at Disney Research. “The expert defines the building blocks, with constraints and composition rules, and paves the way for non-experts to make complex robotic systems. This system will likely inspire follow-up work targeting the computational design of even more intricate robots.”

This research was supported by the National Science Foundation’s Expeditions in Computing program.