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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).
Mars Base

NASA's Morpheus lander in fiery crash at Cape Canaveral | Reuters - 0 views

in.reuters.com/...accident-idINBRE8781A220120810

scibyte58 Morpheus

shared by Mars Base on 10 Aug 12 - No Cached
  • The insect-like vehicle, designed and built by engineers at NASA's Johnson Space Center in Houston, had made several flights attached to a crane before Thursday's attempted free-flight
  • Morpheus' engines, which burn liquid oxygen and methane, appeared to ignite as planned, lifting the 1,750-pound (794 kg) vehicle into the air. But a few seconds later, Morpheus rolled over on its side and plummeted to the ground.
  • An investigation is under way
  • ...3 more annotations...
  • an example of what the former project manager called "“Home Depot engineering" - low-budget projects that use existing resources and partner with non-traditional aerospace companies.
  • Instead of building some elaborate test structure, you go to Home Depot and build something very quickly that gets you 80 percent of the answer and allows you to keep moving forward
  • designed to deliver about 1,100 pounds (500 kg) of cargo to the moon
Mars Base

Study: Old flu drug speeds brain injury recovery - 0 views

medicalxpress.com/...rug-brain-injury-recovery.html

scibyte36

shared by Mars Base on 01 Mar 12 - No Cached
  • reporting the first treatment to speed recovery from severe brain injuries caused by falls and car crashes: a cheap flu medicine whose side benefits were discovered by accident decades ago
Mars Base

May 28 - Today in Science History - Scientists born on May 28th, died, and events - 0 views

www.todayinsci.com/...5_28.htm

scibyte132 LookingBackMay

shared by Mars Base on 25 May 14 - No Cached
  • Mars landing
  • In 1971, the U.S.S.R. Mars 3 was launched. It arrived at Mars on December 2, 1971. The lander was released from the Mars 3 orbiter and became the first spacecraft to land successfully on Mars. It failed after relaying 20 seconds of video data to the orbiter. The Mars 3 orbiter returned data until Aug 1972, sending measurements of surface temperature and atmospheric composition. The first USSR Mars probe was launched 10 Oct 1960, but it failed to reach earth orbit. The next four USSR probes, including Mars 1, also failed. The USA Mariner 3 Mars Flyby attempt in 1964 failed when its solar panels did not open. USA's Mariners 4, 6, and 7 successfully returned Mars photos. Also in 1971, the USSR Mars 2 lander crashed.
  • Animals in space
  • ...1 more annotation...
  • In 1959, Rhesus monkey Abel and squirrel monkey Baker, both female, were launched for a brief suborbital space flight in the nose cone of Jupiter Missile AM-18. They reached 300 miles altitude, and travelled 1500 miles at speeds over 10,000 mph. Heart rate and sounds, body temperature, blood pressure and radiation were monitored, plus muscle performance by electromyogram. Abel was trained to tap a switch when a red light flashed, to collect data on performance. After the mission, their successful recovery was the first for living beings. The monkeys survived the flight. Afterwards Able died during anesthesia as doctors were about to remove an electrode from under her skin. Baker died of kidney failure in 1984 at age 27.
Mars Base

Hulk Smash! Collision That Formed Our Moon Shows Up In Lunar Rocks, Study Says - 0 views

www.universetoday.com/...s-up-in-lunar-rocks-study-says

scibyte134 LunarFormation

shared by Mars Base on 07 Jun 14 - No Cached
  • theory
  • Billions of years ago
  • , a Mars-sized body (sometimes called “Theia”) smashed into our young planet
  • ...14 more annotations...
  • Earth fortunately survived
  • and the fragments from the crash gradually coalesced into the Moon that we see today
  • scientists believe they have found traces of Theia in lunar rocks pulled from the Apollo missions
  • The isotopes or types of oxygen revealed in the new research appear to be different between the Earth and the Moon
  • implies that a body of different composition caused the changes
  • Before, the “resolution” of these microscopes couldn’t find any significant differences
  • the new data reveals the moon rocks have 12 parts per million more oxygen-17 than the Earth rocks
  • “The differences are small and difficult to detect, but they are there,” stated lead researcher Daniel Herwartz
  • means two things
  • first
  • can now be reasonably sure that the giant collision took place
  • Second
  • it gives us an idea of the geochemistry of Theia
  • The work was published in Science and will also be presented at the Goldschmidt geochemistry conference in California on June 11.
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