The Formica project was our favorite presentation at 25C3. The goal is to build open source swarm robots as cheaply as possible. The team ended up building 25 robots in an assembly line fashion. With enough lead time, the price could get as low as £15 each. Each bot has two direct drive cellphone vibration motors with tiny neoprene wheels. They’re controlled by an MSP430 microcontroller. The only really specialized chip is a charge controller so the bots can charge without any intervention. They have copper skis on the front that touch the ground plane plus antennas to contact Vcc. On top of the bot are three IR detectors for both navigation and for transferring firmware updates between bots. A reflective sensor is on the underside for detecting “food”. It looks like a great design and any easy way for anyone to start researching swarm robotics.
In our Dev Phone 1 excitement last week, we somehow overlooked phoneWreck’s teardown of the T-Mobile G1. The complex slider mechanism is certainly worth looking out. One of the major oddities they point out is the inclusion of two vibration motors. One is mounted next to the SIM on the mainboard. While the other is mounted in the frame next to the earpiece. We wonder what was gained/solved by using two. The phone also includes a digital compass module. We’d like a more detailed explanation of how the Xilinx CPLD is used. From this article in 2006, it seems HTC uses them to generate custom clock signals and switching off devices for power management.
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.