With exams behind him [Adam Greig] had time to make a Nerf sentry gun. It’s actually quite easy to pull everything together. He’s got a netbook running Motion, an open source motion sensing program for use with a webcam. When movement is detected an Arduino, connected via a USB cable, actuates a servo to pull the trigger of the gun. The turret itself has seen a battery upgrade that increases the firing speed. It’s fun to see hardware prototyping done with a few pencils and a fist full of cable ties. Check it out after the break.
There are cars that increase the radio volume as you drive faster, and video games that ramp up the music as your gameplay improves (we’re looking at you SSX Tricky). Now you can add that feature to your workout with [Polymithic’s] Motion Feedback MP3 Player. It uses a passive infrared sensor to detect motion so there’s no need to wear any electronics. But if you used some Bluetooth headphones you could bring the system with you to the gym, just don’t exercise so hard that you blow your eardrums out.
We’re not 100% sure the usefulness of this hack, but it is extremely interesting regardless and will probably make a lot of furries happy. WolfTronix presents their method for creating a realistic animatronic wolf tail. It uses an Atmel MCU controlling two servos alongside a mess of Klixx toys and paper clips to produce a nice wag motion. The guide is extremely detailed and looks to be fun, so long as you don’t mind the monotonous task of shaving off potentially hundreds of ‘nubs’ as they call them. Either way, you’ll definitely have the best (and only…) tail on the block.
People tend not to think about the non-Newtonian properties of foodstuffs, but we’re glad at least one person did. When it comes to cornstarch, it’s indeterminate viscosity when mixed with water made it the perfect solution for a pretty neat trick: making a liquid move in reaction to a subwoofer. The unique motion can be attributed to the physical properties of the solution: when enough force is applied quickly, it acts as a solid. Otherwise, it flows like a liquid. The erratic bouncing of the sound waves combined with a little tactile manipulation create varying degrees and speeds of applied pressure, which in turn create a mass of flowing shapes that almost appear to be alive.
We’ve covered weird fluids before, but this is perhaps most similar to SnOil, a game that uses ferrofluids to achieve a similar result. SnOil, however, does not depend of vibrations to create shapes in the fluid, it uses small electromagnets and magnetically charges liquid instead. We love the ordered appearance of the SnOil unit, but the chaotic motion of the cornstarch and it’s non-Newtonian properties make it appear almost otherworldly. We wonder how ferrofluids would react in a situation similar to the cornstarch above, since it would respond to both the vibration and the voice coil’s magnetic field.
Our friend [Johnny Lee] has been quite busy traveling and moving to a new city. He hasn’t had time to put together any new videos because of this. He’s been doing more Wiimote research though and has put together an extensive post about what he’s working on and thinking about.
Right before the move, he put together a demo for throwable displays. The square pieces of foamcore have retro-reflective tape added to each of the corners. The Wiimote sees the orientation of the square and adjusts the projected image to fit perfectly; even when you pick it up and throw it. He used it to add a trail to an airhockey puck. Embedded above is an earlier project where he used the Wiimote to track a foldable display and project accordingly.
[Johnny] has also been working on 3D tracking with two or more Wiimotes. Since the Wiimote is camera based, stereo triangulation is simple. Check out the video below from the University of Cambridge that uses two Wiimotes for motion capture.
Have a look at [Johnny Lee]’s full post for even more Wiimote ideas.