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The Wii's MEMS Inventor on Future Technology
eldavojohn writes "IEEE Spectrum is running an article on the inventor of the motion sensor that the Wii uses. The microelectromechanical system (MEMS) gives Wii its core ability to sense motion in the controller. What's really interesting is where Benedetto Vigna wants to take this technology. He has plans to make the sensor smaller and tougher, and hope to place it inside of things like shoes, textiles, and medical devices to aid in data collection. He continues, 'Then I want to make a three-dimensional gyroscope, to measure rotation around three different axes. Today, such products are quite big, a cube 10 centimeters on a side. We want to do this in less than a 30-millimeter cube, to serve as an image stabilizer in cameras and to track a person's position in the intervals when he can't get a GPS signal.'"
I have not played with a Wii yet, but knowing something about robotics I can say that if they manage to get a 3D sensor set working, and cheaply, it will advance a gazillion projects. Knowing how and when to place mechanical effectors and movement of devices is a terribly difficult problem generally. This type of sensor will help do that very effectively.
This can be used in conjunction with other sensor systems to do things like create a lawnmower robot that doesn't just wonder around till you turn it off. Being able to manage calculation of 3D space is very intensive, but doing so lets us get one step closer to the robot maid and other cartoon dreams of days gone by.
Its not just for games. Most of the semi-successful DARPA grand challenge vehicles used a similar device for navigation support. The reality of a car that drives you (in Soviet Russia) to work without any intervention from you is getting very close. Inertial navigation (AFAIK) relies on 3D motion tracking to determine the motion in between points of absolute (or relatively absolute) positioning data. So, in between GPS readings, inertial navigation estimates where the robot/car/vehicle is in relation to previous GPS readings. I've seen robots do this already, its just not cheap enough for everyone. A small R/C sized robot can travel 1/2 mile and return to its starting point with high accuracy despite obstacles using inertial navigation. This can be applied to a lot of systems.
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GPS for gross location, MEM gyroscope for tracking small changes in velocity, position, orientation, etc., and when GPS fails.
The Crista Inertial Measurement Unit is a very small three axis inertial sensor that provides high resolution digital rate and acceleration data via serial interfaces. It uses MEMS gyroscopic rate sensors and accelerometers mounted on orthogonal axes to provide 300 /sec rate and 10G acceleration data.
Small (2" x 1.5" x 1", 37g )
http://www.cloudcaptech.com/crista_imu.htm
This guy needs to spend 5 minutes googling for IMUs (intertial measurement units).
For instance, this unit:
http://www.memsense.com/products/mag3.asp
There are a million of these out there...
Has three axes of accelerometers, three axes of rate gyros and a three axis magnetometer... all in a package that is
(this is offended to the end of comments you post, 120 chars)
The principle is the same although the practice is different. Each integration accumulates error, so adding the extra layer degrades the performance.
These ideas aren't new and have been knocking around for a while. The article sounds a little like hype / ego-wanking, but then again IEEE Spectrum articles normally are. There is a ton of work on "sensor fusion". The basic idea is to take several low-grade position sources and then fuse them together to create a (hopefully) high-accuracy position source. The robotics and wearables communities have been looking at this for many years. One nice approach is combinng the sensor inputs in a Kalman filter which does actually create a higher accuracy signal than any individual source.
As far as the claims about 3d gyroscopes being the next big thing when they are reduced in size - we saw a demo of a commerically available product about two years ago. It is a 1cm cube that intergrates several accelerometers and gyroscopes to provide a dead-reckoning position source that is accurate to within 5cm. It was very impressive, although the cube cost several thousand pounds. It would be pretty amazing to see Nintendo pick up on something like that.
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The motion sensors aren't the unique part of the Wii. Sony's controller has the equivalent motion sensors. The unique part of the Wii is the combination of the motion sensors with the IR bar tracking to give you a non-drifting reference.
By themselves, the motion sensors will get further and further off position. For example, if one turned right 90 degrees and then returned, the motion sensors by themselves would cause you to calculate a position not-quite matched up your original - and the more you move the more the reference will drift as measurement errors accumulate. With the IR bar, the reference can be corrected so the controller can stay oriented correctly vs the screen.
This is why Sony's controller is a very poor substitute for the Wii controller.