We nearly passed over this tip from [xoxu] which was just a few links to some AliExpress pages. However, when we dug a bit into the pages we found something pretty surprising. Somewhere out there in the wild we…east of China there’s a company not only reverse engineering the Mini Cheetah, but improving it too.
We cover a lot of Mini Cheetah projects; it’s a small robot that can do a back-flip after all. When compared to the servo quadruped of not so many years ago it’s definitely exciting magic. Many of the projects go into detail about the control boards and motor modifications required to build a Mini Cheetah of your own. So we were especially interested to discover that this AliExpress seller has gone through the trouble of not just reverse engineering the design, but also improving on it. Claiming their motors are thinner and more dust resistant than what they’ve seen from MIT.
To be honest, we’re not sure what we’re looking at. It’s kind of cool that we live in a world where a video of a research project and some papers can turn into a $12k robot you can buy right now. Let us know what you think after the break.
It seems like modern roboticists have decided to have a competition to see which group can develop the most terrifying robot ever invented. As of this writing the leading candidate seems to be the robot that can fuel itself by “eating” organic matter. We can only hope that the engineers involved will decide not to flesh that one out completely. Anyway, if we can get past the horrifying and/or uncanny valley-type situations we find ourselves in when looking at these robots, it turns out they have a lot to teach us about the theories behind a lot of complicated electric motors.
This research paper (gigantic PDF warning) focuses on the construction methods behind MIT’s cheetah robot. It has twelve degrees of freedom and uses a number of exceptionally low-cost modular actuators as motors to control its four legs. Compared to other robots of this type, this helps them jump a major hurdle of cost while still retaining an impressive amount of mobility and control. They were able to integrate a brushless motor, a smart ESC system with feedback, and a planetary gearbox all into the motor itself. That alone is worth the price of admission!
Computer games have been around about as long as computers have. And though it may be hard to believe, Zork, a text-based adventure game, was the Fortnite of its time. But Zork is more than that. For portability and size reasons, Zork itself is written in Zork Implementation Language (ZIL), makes heavy use of the brand-new concept of object-oriented programming, and runs on a virtual machine. All this back in 1979. They used every trick in the book to pack as much of the Underground Empire into computers that had only 32 kB of RAM. But more even more than a technological tour de force, Zork is an unmissable milestone in the history of computer gaming. But it didn’t spring up out of nowhere.
The computer revolution had just taken a fierce hold during the second World War, and showed no sign of subsiding during the 1950s and 1960s. More affordable computer systems were becoming available for purchase by businesses as well as universities. MIT’s Laboratory for Computer Science (LCS) was fortunate to have ties to ARPA, which gave MIT’s LCS and AI labs (formerly part of Project MAC) access to considerable computing resources, mostly in the form of DEC PDP systems.
The result: students at the MIT Dynamic Modeling Group (part of LCS) having access to a PDP-10 KA10 mainframe — heavy iron at the time. Though this PDP-10 was the original 1968 model with discrete transistor Flip Chip modules and wire-wrapping, it had been heavily modified, adding virtual memory and paging support to expand the original 1,152 kB of core memory. Running the MIT-developed Incompatible Timesharing System (ITS) OS, it was a highly capable multi-user system.
Recycling is on paper at least, a wonderful thing. Taking waste and converting it into new usable material is generally more efficient than digging up more raw materials. Unfortunately though, sorting this waste material is a labor-intensive process. With China implementing bans on waste imports, suddenly the world is finding it difficult to find anywhere to accept its waste for reprocessing. In an attempt to help solve this problem, MIT’s CSAIL group have developed a recycling robot.
The robot aims to reduce the reliance on human sorters and thus improve the viability of recycling operations. This is achieved through a novel approach of using special actuators that sort by material stiffness and conductivity. The actuators are known as handed shearing auxetics – a type of actuator that expands in width when stretched. By having two of these oppose each other, they can grip a variety of objects without having to worry about orientation or grip strength like conventional rigid grippers. With pressure sensors to determine how much a material squishes, and a capacitive sensor to determine conductivity, it’s possible to sort materials into paper, plastic, and metal bins.
The research paper outlines the development of the gripper in detail. Care was taken to build something that is robust enough to deal with the recycling environment, as well as capable of handling the sorting tasks. There’s a long way to go to take this proof of concept to the commercially viable stage, but it’s a promising start to a difficult resource problem.
MIT is well known for rigorous courses, but they also have a special four-week term at the start of each year called the IAP — Independent Activities Period. This year, the MIT Radio Society had several interesting presentations on both the history and application of radio. You weren’t there? No problem, as the nine lecture were all recorded for you to watch at your leisure. You can see one of the nine, below.
These aren’t some five minute quicky videos, either. They are basically live captures that run anywhere from an hour to almost two hours in length. The topics are a great mix including radio history, software-defined radio, propagation, radio astronomy, RADAR, and even 5G.
You might have to pick and choose. Some of the lectures are suitable for just about anyone. Some assume a bit more radio expertise in electronics or math. Still, they are all worth at least a cursory skim to see if you want to really sit and watch in detail. The only nitpick is that some presenters used a laser pointer that doesn’t show up on the inset slide graphics in the video. That makes sense because the inset slides are not really in the room, but it can make it a little difficult to understand what the speaker is pointing to on a crowded slide.
Of course, if you want to dive deep and you need more background, MIT — along with many other institutions — will let you use their learning material for free. We were especially fans of the circuits class but there are many others including just raw materials from OCW.
What if I told you that you can get rid of your headphones and still listen to music privately, just by shooting lasers at your ears?
The trick here is something called the photoacoustic effect. When certain materials absorb light — or any electromagnetic radiation — that is either pulsed or modulated in intensity, the material will give off a sound. Sometimes not much of a sound, but a sound. This effect is useful for spectroscopy, biomedical imaging, and the study of photosynthesis. MIT researchers are using this effect to beam sound directly into people’s ears. It could lead to devices that deliver an audio message to specific people with no hardware on the receiving end. But for now, ditching those AirPods for LaserPods remains science fiction.
There are a few mechanisms that explain the photoacoustic effect, but the simple explanation is the energy causes localized heating and cooling, the material microscopically expands and contracts, and that causes pressure changes in the sample and the surrounding air. Saying pressure waves in air is just a fancy way of explaining sound.
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.