[Sergii] has been learning about robot simulation and wrote up a basic simulator for a robodog platform: the Unitree A1. It only took about 800 lines of code to do so, which probably makes it a good place to start if one is headed in a similar direction.
Right now, [Sergii]’s simulator is an interactive physics model than runs in the browser. Software-wise, once the model of the robot exists the Rapier JavaScript physics engine takes care of the physics simulation. The robot’s physical layout comes from the manufacturer’s repository, so it doesn’t need to be created from scratch.
To make the tool useful, the application has two models of the robot, side by side. The one on the left is the control model, and has interactive sliders for limb positions. All movements on the control model are transmitted to the model on the right, which is the simulation model, setting the pose. The simulation model is the one that actually models the physics and gravity of all the desired motions and positions. [Sergii]’s next step is to use the simulator to design and implement a simple walking gait controller, and we look forward to how that turns out.
If Unitree sounds familiar to you, it might be because we recently covered how an unofficial SDK was able to open up some otherwise-unavailable features on the robodogs, so check that out if you want to get a little more out of what you paid for.
A report released this week suggests that 50 flights into its five-flight schedule, the Mars helicopter might be starting to show its age. The report details a protracted communications outageIngenuity’s flight controllers struggled with for six sols after flight 49 back in April. At first attributed to a “communications shadow” caused by the helicopter’s robotic buddy, Perseverance, moving behind a rocky outcrop and denying line of sight, things got a little dicey once the rover repositioned and there was still no joy. Since the helicopter has now graduated from “technology demonstration” to a full-fledged member of the team tasked with scouting locations for the rover while respecting the no-fly zone around it, it was essential to get it flying again. Several attempts to upload a flight plan failed with nothing but an acknowledgment signal from the helicopter, but a final attempt got the program uploaded and flight 50 was a complete if belated success. So that’s good, but the worrying news is that since Sol 685, the helicopter has been switching in and out of nighttime survival mode. What that portends is unclear, but no matter how amazing the engineering is, there’s only so much that can be asked on Ingenuity before something finally gives.
They say a picture is worth a thousand words, but an animation, then, must be worth a million. Make that animation interactive, and… well, we don’t know how many words it is worth, but it is plenty! That’s the idea behind [Bartosz Ciechanowski’s] blog where he uses clever interactive animations to explain the surprisingly complex physics of riding a bicycle.
The first animation lets you view a rider from any angle and control the rider’s pose. Later ones show you how forces act on the rider and bicycle, starting with example wooden boxes and working back up to the original bike rider with force vectors visible. As you move the rider or the bike, the arrows show you the direction and magnitude of force.
Although neutrinos are exceedingly common, their near-massless configuration means that their presence is rather ephemeral. Despite billions of them radiating every second towards Earth from sources like our Sun, most of them zip through our bodies and this very planet without ever interacting with either. This property is also what makes studying these particles that are so fundamental to our understanding so complicated. Fortunately recently published results by researchers behind the SNO+ neutrino detector project shows that we may see a significant bump in our neutrino detection sensitivity.
The Sudbury Neutrino Detector (Courtesy of SNO)
In their paper (preprint) in APS Physical Review Letters, the researchers describe how during the initial run of the new SNO+ neutrino detector they were able to detect anti-neutrinos originating from nuclear fission reactors over 240 kilometers away, including Canadian CANDU and US LWR types. This demonstrated the low detection threshold of the SNO+ detector even in its still incomplete state between 2017 and 2019. Filled with just heavy water and during the second run with the addition of nitrogen to keep out radioactive radon gas from the surrounding rock of the deep mine shaft, SNO+ as a Cherenkov detector accomplished a threshold of 1.4 MeV at its core, more than sufficient to detect the 2.2 MeV gamma radiation from the inverse beta decays (IBD) that the detector is set up for.
The SNO+ detector is the evolution of the original Sudbury Neutrino Observatory (SNO), located 2.1 km below the surface in the Creighton Mine. SNO ran from 1999 to 2006, and was part of the effort to solve the solar neutrino problem, which ultimately revealed the shifting nature of neutrinos via neutrino oscillation. Once fully filled with 780 tons of linear alkylbenzene as a scintillator, SNO+ will investigate a number of topics, including neutrinoless double beta decay (Majorana fermion), specifically the confounding question regarding whether neutrinos are its own antiparticle or not
The focus of SNO+ on nearby nuclear fission reactors is due to the constant beta decay that occurs in their nuclear fuel, which not only produces a lot of electron anti-neutrinos. This production happens in a very predictable manner due to the careful composition of nuclear fuel. As the researchers noted in their paper, SNO+ is accurate enough to detect when a specific reactor is due for refueling, on account of its change in anti-neutrino emissions. This is a property that does not however affect Canadian CANDU PHWRs, as these are constantly refueled, making their neutrino production highly constant.
Each experiment by SNO+ produces immense amounts of data (hundreds of terabytes per year) that takes a while to process, but if these early results are anything to judge by, then SNO+ may progress neutrino research as much as SNO and kin have previously.
Going to the movies is an experience. But how popular do you think they’d be if you went in, bought your popcorn, picked your seat, and the curtain would rise on a large still photograph? Probably not a great business model. If a picture is worth 1,000 words, then a video is worth at least a million, and that’s why we thought it was awesome that Tinkercad now has a physics simulator built right in.
Look for this icon on the top right toolbar.
It all starts with your 3D model or models, of course. Then there’s an apple icon. (Like Newton, not like Steve Jobs.) Once you click it, you are in simulation mode. You can select objects and make them fixed or movable. You can change the material of each part, too, which varies its friction, density, and mass. There is a play button at the bottom. Press it, and you’ll see what happens. You can also share and you have the option of making an MP4 video like the ones below.
We, of course, couldn’t resist. We started with a half-sphere and made it larger. We also rotated it so the flat side was up. We then made a copy that would become the inside of our bowl. Using the ruler tool, we shaved about 2 mm off the length and width (X and Y) of the inner sphere. We also moved it 2 mm up without changing the size.
Using the alignment tools, you can then center the inner piece in the X and Y axis. Change the inner color to a hole and group the objects. This forms a simple bowl shape. Then we moved the workplane to a random part of the inner surface of our bowl and dropped a sphere. Nothing complicated.
For those of us who like to crawl over complex systems, spending hours or even days getting hardware and software to work in concert, working at places like NASA or CERN seems like a dream job. Imagine having the opportunity to turn a wrench on the Space Shuttle or the Large Hadron Collider (LHC) — not only do you get to spend some quality time with some of the most advanced machines ever produced, you can be secure in the knowledge that your work will further humanity’s scientific understanding of the universe around us.
Or at least, that’s what we assume it must feel like as outsiders. But what about somebody who’s actually lived it? What does an actual employee, somebody who’s had to wake up in the middle of the night because some obscure system has gone haywire and stalled a machine that cost taxpayers $4.75 billion to build, think about working at the European Organization for Nuclear Research? Continue reading “Daniel Valuch Chats About CERN’s High Caliber Hacking”→
One of the great things about the Hackaday community is how quickly you find out what you don’t know. That’s not a bad thing, of course; after all, everyone is here to get smarter, right? So let’s work together to get our heads around this paper (PDF) by [Zerina Kapetanovic], [Miguel Morales], and [Joshua R. Smith] from the University of Washington, which purports to construct a low-throughput RF transmitter from little more than a resistor.
This witchcraft is made possible thanks to Johnson noise, also known as Johnson-Nyquist noise, which is the white noise generated by charge carriers in a conductor. In effect, the movement of electrons in a material thanks to thermal energy produces noise across the spectrum. Reducing interference from Johnson noise is why telescopes often have their sensors cooled to cryogenic temperatures. Rather than trying to eliminate Johnson noise, these experiments use it to build an RF transmitter, and with easily available and relatively cheap equipment. Continue reading “A Single-Resistor Radio Transmitter, Thanks To The Power Of Noise”→
