



SAN FRANCISCO – To gamers, $40 may seem like a steep price to replace a Wii remote controller, but to scientists, a hacked Wiimote is a steal compared to the pricey sensors needed for a lot of field research.

Inspired by videos of renowned hacker Johnny Chung Lee turning the Wiimote into a finger-tracking device and a touchscreen white board, physicist Rolf Hut of Delft University of Technology built a Wiimote wind sensor.

"It was just a bendy pole with an empty bottle on top with an LED light on the bottle," Hut said. "And it swayed in the wind."

The Wiimote can track just about anything: All that's needed is an LED light. Hydrologist Willem Luxemburg of Delft University of Technology in the Netherlands demonstrated a hacked water-level sensor made from a Wiimote and a plastic boat at the meeting of the American Geophysical Union here Monday.

"Just switch it on and make sure it doesn't get wet," Luxemburg said.

Luxemburg's team aimed the Wiimote at a problem that can be very tricky for hydrologists: measuring evaporation on a body of water. The easiest way to measure evaporation is to place pans of water near the lake, or whatever water is being studied, and put pressure sensors in them. The sensors record the drop in pressure as more and more water disappears. But this equipment can run $500 or more, and still the measurements aren't accurate because the water in the pan gets warmer on land than it would in the lake. Alternatively, measuring the level of water in a pan that is floating in a lake is also tricky because the pan will inevitably be moving.

The Wiimote could overcome the evaporation-measurement problems. It has a tri-axial accelerometer and a high-resolution, high-speed infrared camera, which can sense movement with better than 1 millimeter accuracy.

Luxemburg's team tested it in a floating evaporation pan, using a float with an LED. With a Wiimote aimed at the float, and some hacking and programming of the Wiimote's output, they were able to get highly accurate, real-time data on water level wirelessly sent to a laptop.

The IR camera can track up to four LED lights at once, so scientists can use several floats to calculate the water's plane. To be as accurate with pressure sensors, you'd need more and costlier units.

Luxemburg and Hut's goal was to show other scientists at the meeting that the videogame controller can be a legitimate piece of scientific equipment that they should consider deploying in all types of field experiments. They've gotten interest from colleagues who study building construction at Delft University because of the controller's accelerometer.

"If you have a structure that collapses and you have Wiimotes on the building, you could see how fast it falls," Luxemburg said.

And judging from the crowd at their demonstration, plenty of scientists are interested.

"I'm pretty sure within the next four to six weeks, some good ideas will come along," Hut said.

Of course, each experiment will have it's own challenges that require specific hacking of the Wiimote. It will need longer battery life and a way to store data so it can be left to work alone at a field site. But Hut is confident all that can be done, and more.

"I still want to do something to measure temperature with it," Hut said. "I just don't know how yet."

But the basics, he said, are easy. His original wind-sensor demo took him just a few hours to build and was a welcome break from the network and signal analysis he usually does.

"There are probably better ways to measure wind, but it was a day well-spent," Hut said. "I really felt the need to solder something."



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Images: 1) Betsy Mason/Wired.com. 2) Hubert Savenijel/ Delft University of Technology. 3) Betsy Mason/Wired.com.

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