Not that we don’t love Star Trek, but the writers could never decide if ion propulsion was super high tech (Spock’s Brain) or something they used every day (The Menagerie). Regardless, ion propulsion is real and we have it today on more than one spacecraft. However, MIT recently demonstrated an ion-powered airplane. How exciting! An airplane with no moving parts that runs on electricity. Air travel will change forever, right? According to [Real Engineering], ion-propelled (full-sized) aircraft run into problems with the laws of physics. You can see the video explaining that, below.
To understand why, you need to know two things: how ion drive works and how the engines differ when using them in an atmosphere. Let’s start with a space-based ion engine, a topic we’ve covered before. Atoms are turned into ions which are accelerated electrically. So the ion engine is just using electricity to create thrust exhaust instead of burning rocket fuel.
If you think about 3D printing, the ultimate goal would be to lay down specific atoms or molecule and build anything. Despite a few lab demonstrations at that scale, generally, it is easier to print in the macro scale than the micro. While it won’t get down to the molecule level, implosion fabrication is a new technique researchers hope will allow you to print large things and then shrink them. The paper describing the process appeared in Science. If you don’t want to pay your way through the paywall, you can read a summary on NewScientist or C&EN. Or you can scour the usual sources.
The team at MIT uses the same material that is found in disposable diapers. A laser traces patterns and the light reacts to a chemical implanted in the diaper material (sodium polyacrylate). That material can swell to many times its normal size which is why it is used in diapers. In this case, though, the material is swollen first and then reduced back to normal size.
Neural networks use electronic analogs of the neurons in our brains. But it doesn’t seem likely that just making enough electronic neurons would create a human-brain-like thinking machine. Consider that animal brains are sometimes larger than ours — a sperm whale’s brain weighs 17 pounds — yet we don’t think they are as smart as humans or even dogs who have a much smaller brain. MIT researchers have discovered differences between human brain cells and animal ones that might help clear up some of that mystery. You can see a video about the work they’ve done below.
Neurons have long finger-like structures known as dendrites. These act like comparators, taking input from other neurons and firing if the inputs exceed a threshold. Like any kind of conductor, the longer the dendrite, the weaker the signal. Naively, this seems bad for humans. To understand why, consider a rat. A rat’s cortex has six layers, just like ours. However, whereas the rat’s brain is tiny and 30% cortex, our brains are much larger and 75% cortex. So a dendrite reaching from layer 5 to layer 1 has to be much longer than the analogous neuron in the rat’s brain.
These longer dendrites do lead to more loss in human brains and the MIT study confirmed this by using human brain cells — healthy ones removed to get access to diseased brain cells during surgery. The researchers think that this greater loss, however, is actually a benefit to humans because it helps isolate neurons from other neurons leading to increased computing capability of a single neuron. One of the researchers called this “electrical compartmentalization.” Dig into the conclusions found in the research paper.
We couldn’t help but wonder if this research would offer new insights into neural network computing. We already use numeric weights to simulate dendrite threshold action, so presumably learning algorithms are making weaker links if that helps. However, maybe something to take away from this is that less interaction between neurons and groups of neurons may be more helpful than more interaction.
Watching them probe neurons under the microscope reminded us of probing on an IC die. There’s a close tie between understanding the brain and building better machines so we try to keep an eye on the research going on in that area.
If someone suggests you spend time working on boring projects, would you take that advice? In this case, I think Kipp Bradford is spot on. We sat down together at the Hackaday Superconference last fall and talked about medical device engineering, the infrastructure in your home, applying Sci-Fi to engineering, and yes, we spoke about boring projects.
Kipp presented a talk on Devices for Controlling Climates at Supercon last year. It could be argued that this is one of those boring topics, but very quickly you begin to grasp how vitally important it is. Think about how many buildings on your street have a heating or cooling system in them. Now zoom out in your mind several times to neighborhood, city, state, and country level. How much impact will a small leap forward have when multiplied up?
The next Hackaday Superconference is just around the corner. Before you join us below for the interview with Kipp, make sure you grab your 2018 Hackaday Superconference ticket to be there for great talks like Kipp’s!
Let’s face it, one of the challenges of wearable electronics is that people are filthy. Anything you wear is going to get dirty. If it touches you, it is going to get sweat and oil and who knows what else? And on the other side it’s going to get spills and dirt and all sorts of things we don’t want to think about on it. For regular clothes, that’s not a problem, you just pop them in the washer, but you can’t say the same for wearable electronics. Now researchers at MIT have embedded diodes like LEDs and photodetectors, into a soft fabric that is washable.
Traditionally, fibers start as a larger preform that is drawn into the fiber while heated. The researchers added tiny diodes and very tiny copper wires to the preform. As the preform is drawn, the fiber’s polymer keeps the solid materials connected and in the center. The polymer protects the electronics from water and the team was able to successfully launder fabric made with these fibers ten times.
Stand up right now and walk around for a minute. We’re pretty sure you didn’t see everywhere you stepped nor did you plan each step meticulously according to visual input. So why should robots do the same? Wouldn’t your robot be more versatile if it could use its vision to plan a path, but leave most of the walking to the legs with the help of various sensors and knowledge of joint positions?
That’s the approach [Sangbae Kim] and a team of researchers at MIT are taking with their Cheetah 3. They’ve given it cameras but aren’t using them yet. Instead, they’re making sure it can move around blind first. So far they have it walking, running, jumping and even going up stairs cluttered with loose blocks and rolls of tape.
Jumping 30 inches onto a desk
Two algorithms are at the heart of its being able to move around blind.
The first is a contact detection algorithm which decides if the legs should transition between a swing or a step based on knowledge of the joint positions and data from gyroscopes and accelerometers. If it tilted unexpectedly due to stepping on a loose block then this is the algorithm which decides what the legs should do.
The second is a model-predictive algorithm. This predicts what force a leg should apply once the decision has been made to take a step. It does this by calculating the multiplicative positions of the robot’s body and legs a half second into the future. These calculations are done 20 times a second. They’re what help it handle situations such as when someone shoves it or tugs it on a leash. The calculations enabled it to regain its balance or continue in the direction it was headed.
There are a number of other awesome features of this quadruped robot which we haven’t seen in others such as Boston Dynamics’ SpotMini like invertible knee joints and walking on three legs. Check out those features and more in the video below.
Most of us take it for granted that water is as close as your kitchen tap. But that’s not true everywhere. Two scientists at MIT have a new method for harvesting water from fog, especially fog released from cooling towers such as those found from power plants. It turns out, harvesting water from fog isn’t a new idea. You typically insert a mesh into the air and collect water droplets from the fog. The problem is with a typical diameter of 10 microns, the water droplets mostly miss the mesh, meaning they typically extract no more than 2% of the water content in the air.
The team found two reasons for the low efficiency. Water clogs the mesh openings which can be somewhat mitigated by using coated meshes that shed water quickly. Even in the lab that only increases the yield to about 10%. The bigger problem, though, is basically only some of the droplets hit the mesh, and even those that do may not stick because of drag. Fine meshes can help but are harder to make and have low structural integrity. Their solution? Inject ions into the fog to charge the water droplets and impart the opposite charge on the mesh.
