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Mars Base

Physicist creates scale model of LHC ATLAS experiment of out LEGO blocks - 0 views

www.physorg.com/...cist-scale-lhc-atlas-lego.html

scibyte27

shared by Mars Base on 30 Dec 11 - No Cached
  • The Large Hadron Collider at the European Organization for Nuclear Research (CERN) in Switzerland has generated a lot of news of late, e.g. the announcement that a team had found what it believes to be a particle that traveled faster than he speed of light, an actual new particle, and of course the seemingly never-ending storyline associated with the hopeful discovery of the elusive Higgs Boson, now a physicist not associated with the project, has built a scale model replica of the ATLAS experiment; a particle detector that will likely serve as ground zero should the so-called “god particle” ever be observed.
  • a physicist with the Niels Bohr Institute took almost thirty five hours to build and cost two thousand Euros (paid for by the high energy physics group at the university). The point of building the replica, he says, is to incite interest in physics. Plus, no doubt, it was sort of fun.
  • The real ATLAS project is 44 meters long and 22 meters wide and weighs 7000 tonnes. Mehlhase’s model, at approximately 1:50 scale is approximately 1 meter long by a half meter wide. And while the real deal has millions of parts, the model has 9500 pieces, mostly LEGO blocks.
  • ...4 more annotations...
  • first tried to model the ATLAS on computer, but then apparently found the undertaking untenable
  • Abandoning that approach, he set to work replicating the ATLAS by simply mimicking what it looked like
  • Mehlhase says he’s contacted LEGO (a Danish company) in hopes of having his model included as one of the model kits sold by the company, though he hasn’t yet made a manual. He’d like to see similar models constructed in schools all over the world.
  • To give some perspective, he modeled some tiny physicists as well.
Mars Base

Double Dispatch: Self-Balancing Electric Unicycle - 0 views

www.stephanboyer.com/...lancing-electric-unicycle.html

scibyte27

shared by Mars Base on 30 Dec 11 - No Cached
  • A custom MIG-welded steel chassisA 450 Watt electric motorTwo 7 Ah 12 Volt batteriesA 5DOF intertial measurement unitThe OSMC H-bridgeAn ATmega328P microcontroller
  • operates much like a Segway -- you lean forward to accelerate, and lean back to brake
  • holding in my right hand (in the video at the bottom) is a "kill switch" -- if I let go of it, the unicycle deactivates the motor,
  • ...3 more annotations...
  • Bullet integrates readings from the gyro and accelerometer using a complementary filter. To balance, the angle estimate is fed through a PID loop (with no integral term). The loop runs at 625 Hz. The output from this stage determines the duty cycle of a 1.22 kHz PWM signal, which is connected to the H-bridge. The code was written in C, and is in the public domain.
  • It took me several hours to be able to ride in a straight line without crashing, and it took several days to learn how to turn in a controlled manner. Many of my friends have tried riding it, usually with little success (including some actual unicyclers).
  • I am certainly not the first person to build an electric unicycle. Perhaps the most well-known self-balancing unicycle is Trevor Blackwell's Eunicycle, which also uses the OSMC. His design is similar to mine, but uses a much more expensive battery pack ($218 for his vs $44 for mine). Also, the Eunicycle's motor and gearbox cost a grand total of $644, whereas Bullet's drive system (including the wheel itself) was $195. Finally, the IMU he uses is about $100 more than mine. Overall, Bullet is several hundred dollars cheaper than the Eunicycle, but this comes at a price (mostly weight).
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