A Simple Posture Sensor

ChairPosture

If you are on the computer for a large part of the day, posture becomes a serious issue that can negatively impact your health. [Wingman] saw this problem, and created a hack to help solve it. His simple posture sensor will monitor the position of your head relative to the chair, and reminds you to sit up straight.

The posture sensor is built around the HC-SR04 ultrasonic distance sensor, an Attiny85, and a piezo speaker. We’ve seen this distance sensor used in the past for a few projects. Rather than going down the wearable route, which has its own drawbacks, [Wingman] decided to attach his sensor on the back of his chair. The best part is that the sensor is not mounted directly on the chair, but rather on a piece of fabric allowing it to be easily moved when needed.

Given how low-cost and small the sensor is, the project can be easily expanded by adding multiple sensors in different locations. This would allow the angle of the back and possibly the neck to be determined, giving a more accurate indicator of poor posture. There are very few hacks out there that address bad posture. Do you have a project that helps address bad posture? Have you used video processing or a wearable device to monitor your posture? Let us know in the comments an don’t forget to send post links about them to our tips line.

[Frank] builds a chair from a sequoia

chair[Frank Howarth] is a very competent woodworker known on the YouTubes for his wonderful stop-motion videos of turned wood bowls. Lately, though, he’s put some effort into building furniture, this time a beautiful lawn chair made from a gigantic sequoia log.

A few years ago, [Frank] and a friend acquired a gigantic sequoia log and milled it themselves with a chainsaw. After two summers, the huge boards were finally dry enough to be used and [Frank] decided a lawn chair would be a fine project.

The sides of the chair are a single monolithic piece of wood. Of course [Frank] needed to cut the sides in half and join them together again for the decorative holes, but it’s still an impressively solid piece of woodworking. The back and seat of the chair are also made out of the same sequoia board, cut into slats held together with three very large dowel rods.

This project probably wouldn’t be possible if it weren’t for the awesome equipment and tools [Frank] has in his shop. He has a great tour of his shop available for your viewing. We should all be so lucky.

DRM Chair only works 8 times

chair

Download a song from iTunes, and you can only add that song to the music library of five other computers. Grab a copy of the latest Microsoft Office, and you’d better hope you won’t be upgrading your computer any time soon. Obviously DRM is a great tool for companies to make sure we only use software and data as intended, but outside planned obsolescence, there isn’t much in the way of DRM for physical objects.

This is where a team from the University of Art and Design in Lausanne, Switzerland comes in. They designed a chair that can only be sat upon eight times. After that, the chair falls apart necessitating the purchase of a new chair. Somewhere in the flat-pack furniture industry, someone is kicking themselves for not thinking of this sooner while another is wondering how they made a chair last so long.

The design of the chair is fairly simple; all the joints of the chair are cast in wax with a piece of nichrome wire embedded in the wax. An Arduino with a small switch keeps track of how many times the chair has been used, while a solenoid taps out how many uses are left in the chair every time the user gets up. When the internal counter reaches zero, a relay sends power through the nichrome wire, melting the wax, and returning the chair to its native dowel rod and wooden board form.

Melting wax wasn’t the team’s first choice to rapidly disassemble a chair; their first experiments used gunpowder. This idea nearly worked, but it was soon realized no one on the team wanted to sit on a primed and loaded chair. You can see the videos of the wax model failing after the break.

[Read more...]

Motorized binocular chair has you stargazing in comfort

motorized-binocular-chair-for-stargazing-in-comfort

It seems like something out of The Red Green Show but this motorized stargazing chair is a serious piece of astronomical hardware. It has a shelf that places a set of high-power binoculars directly in the user’s line of sight. The elevation is easy to adjust. And a power drill lets you take the whole thing for a spin.

The base has been outfitted with cogs and a chain from an old bicycle. The gear reduction lets a power drill rotate the platform. This worked well enough but [Gary] found that making fine adjustments was rather difficult and more often than not he ended up moving the binoculars to avoid overshooting when adjusting the platform with the drill. Luckily he didn’t give up on the idea. On the eighth and final page of his build log he refines the rotating setup with the help of an ice cream maker. It’s gear box is used as a speed reducer so that a very slow drill speed results in an extremely small heading correction. Now he can view the stars in peace, freed from frustration by a well-refined hack.

Hackaday Links: July 24, 2011

Plasma speakers

Apparently if you run AC and DC currents through a welding torch flame you can use the resulting plasma as a loudspeaker. [Thanks Cody]

Power metering

The Google Power Meter API is no longer in development but that didn’t stop [Pyrofer] from finishing his metering hardware. It uses a reflectance sensor to read the meter instead of using clamp-based current sensing.

Music videos from inside the instrument

Filming from inside of a guitar creates the camera effect seen above which looks like the waveform you’d see on an oscilloscope. [Thanks Philleb]

Hidden messages in audio files

GhostCoder lets you encrypt and hide audio files within other audio files. The thought is, you can piggyback your own data into Torrents that are circling the interwebs.

2×4 Chair

If you’re skilled with a Skill saw you can make a chair out of one 2 by 4. You can see the pattern you’ll have to cut out from the board in the image above, wow!

Rapid furniture prototyping

SketchChair is a piece of software that takes the engineer out of engineering furniture. In a child’s-dream-come-true you draw the outlines you’d like to have, add some legs, and the software pops out a design ready to be laser-cut. The finishing touch of adding palm fiber and felt produces what we imagine is a moderately comfortable place to sit. Now the hard part will be convincing your spouse that you should spend the money building an industrial grade laser cutter because of all the money you’ll save on furniture.

We’re still holding out for furniture that is 3d-printed from rock to match our Flintstone’s motif.

Oh, and as always, video after the break.

[Read more...]

Did that table just move?

A table and chair that can move around by themselves? What’s next, suicide boothsself-replicating robots, and Star Trek styled tablet computers? It seems that [Adam Lassy] is moving in that direction. He took this furniture from Ikea and made some neat modifications to give it mobility. Each of the four legs has wheels on them and the legs themselves rotate in unison to change the direction of travel. We could see the table as a more practical drink delivery system than the Bar2d2. It certainly would make for some great late-night pranks but the chair motors need to be silenced before that can happen.

[Thanks Balbor via Ikea Hacker]

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