impact

5 Articles

A Look Inside The Space Shuttle’s First Printer

August 6, 2024 by 23 Comments

There was even a day not too long ago when printers appeared to be going the way of the dodo; remember the “paperless office” craze? But then, printer manufacturers invented printers so cheap they could give them away while charging $12,000 a gallon for the ink, and the paperless office suddenly suffered an extinction-level event of its own. You’d think space would be the one place where computer users would be spared the travails of printing, but as [Ken Shirriff] outlines, there were printers aboard the Space Shuttle, and the story behind them is fascinating.

The push for printers in space came from the combined forces of NASA’s love for checklists and the need for astronauts in the early programs to tediously copy them to paper; Apollo 13, anyone? According to [Ken], NASA had always planned for the ability to print on the Shuttle, but when their fancy fax machine wasn’t ready in time, they kludged together an interim solution from a US military teleprinter, the AN/UG-74C. [Ken] got a hold of one of these beasts for a look inside, and it holds some wonders. Based on a Motorola MC6800, the teleprinter sported both a keyboard, a current loop digital interface, and even a rudimentary word processor, none of which were of much use aboard the Shuttle. All that stuff was stripped out, leaving mostly just the spinning 80-character-wide print drum and the array of 80 solenoid-powered hammers, to bang out complete lines of text at a time. To make the printer Shuttle-worthy, a 600-baud frequency-shift keying (FSK) interface was added, which patched into the spaceplane’s comms system.

[Ken] does his usual meticulous analysis of the engineering of this wonderful bit of retro space gear, which you can read all about in the linked article. We hope this portends a video by his merry band of Apollo-centric collaborators, for a look at some delicious 1970s space hardware.

Quadcopter With Tensegrity Shell Takes A Beating And Gets Back Up

November 5, 2020 by 11 Comments

Many of us have become familiar with the distinctive sound of multirotor toys, a sound frequently punctuated by sharp sounds of crashes. We’d then have to pick it up and repair any damage before flying fun can resume. This is fine for a toy, but autonomous fliers will need to shake it off and get back to work without human intervention. [Zha et al.] of UC Berkeley’s HiPeRLab have invented a resilient design to do so.

We’ve seen increased durability from flexible frames, but that left the propellers largely exposed. Protective bumpers and cages are not new, either, but this icosahedron (twenty sided) tensegrity structure is far more durable than the norm. Tests verified it can survive impact with a concrete wall at speed of 6.5 meters per second. Tensegrity is a lot of fun to play with, letting us build intuition-defying structures and here tensegrity elements dissipate impact energy, preventing damage to fragile components like propellers and electronics.

But surviving an impact and falling to the ground in one piece is not enough. For independent operation, it needs to be able to get itself back in the air. Fortunately the brains of this quadcopter has been taught the geometry of an icosahedron. Starting from the face it landed on, it can autonomously devise a plan to flip itself upright by applying bursts of power to select propeller motors. Rotating itself face by face, working its way to an upright orientation for takeoff, at which point it is back in business.

We have a long way to go before autonomous drone robots can operate safely and reliably. Right now the easy answer is to fly slowly, but that also drastically cuts into efficiency and effectiveness. Having flying robots that are resilient against flying mistakes at speed, and can also recover from those mistakes, will be very useful in exploration of aerial autonomy.

[IROS 2020 Presentation video (duration 14:16) requires free registration, available until at least Nov. 25th 2020. One-minute summary embedded below]

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Screen Shake In VR, Minus The Throwing Up

January 22, 2019 by 5 Comments

In first-person games, an effective way to heighten immersion is to give the player a sense of impact and force by figuratively shaking the camera. That’s a tried and true practice for FPS games played on a monitor, but to [Zulubo]’s knowledge, no one has implemented traditional screen shake in a VR title because it would be a sure way to trigger motion sickness. Unsatisfied with that limitation, some clever experimentation led [Zulubo] to a method of doing screen shake in VR that doesn’t cause any of the usual problems.

Screen shake doesn’t translate well to VR because the traditional method is to shake the player’s entire view. This works fine when viewed on a monitor, but in VR the brain interprets the visual cue as evidence that one’s head and eyeballs are physically shaking while the vestibular system is reporting nothing of the sort. This kind of sensory mismatch leads to motion sickness in most people.

The key to getting the essence of a screen shake without any of the motion sickness baggage turned out to be a mix of two things. First, the shake is restricted to peripheral vision only. Second, it is restricted to an “in and out” motion, with no tilting or twisting. The result is a conveyance of concussion and impact that doesn’t rely on shaking the player’s view, at least not in a way that leads to motion sickness. It’s the product of some clever experimentation to solve a problem, and freely downloadable for use by anyone who may be interested.

Speaking of fooling one’s senses in VR environments, here is a fascinating method of simulating zero gravity: waterproof the VR headset and go underwater.

[via Reddit]

Rainy Day Fun By Calculating Pi

August 24, 2016 by 14 Comments

If you need a truly random event generator, just wait till your next rainstorm. Whether any given spot on the ground is hit by a drop at a particular time is anyone’s guess, and such randomness is key to this simple rig that estimates the value of pi using raindrop sensors.

You may recall [AlphaPhoenix]’s recent electroshock Settlers of Catan expeditor. The idea with this less shocking build is to estimate the value of pi using the ratio of the area of a square sensor to a circular one. Simple piezo transducers serve as impact sensors that feed an Arduino and count the relative number of raindrops hitting the sensors. In the first video below, we see that as more data accumulates, the Arduino’s estimate of pi eventually converges on the well-known 3.14159 value. The second video has details of the math behind the method, plus a discussion of the real-world problems that cropped up during testing — turns out that waterproofing and grounding were both key to noise-free data from the sensor pads.

In the end, [AlphaPhoenix] isn’t proving anything new, but we like the method here and can see applications for it. What about using such sensors to detect individual popcorn kernels popping to demonstrate the Gaussian distribution? We also can’t help but think of other ways to measure raindrops; how about strain gauges that weigh the rainwater as it accumulates differentially in square and circular containers? Share your ideas in the comments below.

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Beauty In Destruction

October 9, 2009 by 49 Comments

[youtube=http://www.youtube.com/watch?v=QfDoQwIAaXg]

This is not a hack. In fact it’s a promotional montage for a collection of scientific equipment that few of us could likely afford. But like yesterday’s giant marionettes over Berlin, sometimes even a costly and delicately-orchestrated achievement transcends its own not-a-hack-ness, fulfilling our brains’ lust for wonderment all the same.

Kurzzeit of Germany produces ballistics measurement equipment. The video depicts various combinations of projectiles and targets at up to one million frames per second, revealing unexpected beauty in hitherto unseen phenomena, and is the best damn ten minutes you will waste on the internet all day!