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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.'"
How could it be used to track position? I thought the MEMS inside the WII Controller needed constant calibration with the main unit. If you walking around in the forest what is your fixed frame of reference?
Application of this could be interesting especially in places when a little bit of lag does not hurt anything. I have a hobby of photography and a good digital image stabilizer is would be the best thing since sliced bread.
"All you need is ignorance and confidence; then success is sure." -- Mark Twain
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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It is integrating your velocity to estimate where you are between GPS solutions. Navigation and guidance systems for high velocity (read military) devices do this already out of necessity. However, it would also be useful for low velocity situations where you have a spotty GPS signal. In that situation it doesn't have to be perfect to be usefull, especially if the display indicated the approximate error in the estimation by drawing a circle for your position rather than a dot.
Someone should tell him about the solid-state gyros already in use in aircraft instruments. Six years ago at Oshkosh I played with an all-electronic artificial horizon instrument. IIRC, it uses those funky crystals which exhibit piezo-type effects when rotated in space. The entire unit, including LCD, CPU, power supply, backup battery, and of course the three solid-state gyros, was a cylinder about 3"x3"x12".
Even in its infancy, the device was massively, hilariously more reliable than the steam-powered mechanical gyros that are currently standard fare for General Aviation.
And that was six years ago.
All this time, I've been thinking (quite wrongly) that the Wii's controller used these same devices.
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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
FTA "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."
There are such devices now that are compact and capable, such as...
http://www.microstrain.com/3dm-gx1_specs.aspx
I worked with this device last summer implementing a vehicle flight path recorder. It not only has 3 rate gyro's but three 5 mG accelerometers, a compass and processor that implements navigational processing and outputs earth-frame quantities via a serial connection.
Size: 42 x 40 x 15 mm
Since they are always imagining "interesting" uses for new technology, I wonder how the porn industry will implement this technology?
There's already adult websites made exclusively for Wii navegation...
Application of this could be interesting especially in places when a little bit of lag does not hurt anything. I have a hobby of photography and a good digital image stabilizer is would be the best thing since sliced bread.
Please stop spreading the myth that "digital image stabilization" is a valid technology. It's nothing but snake oil by digital camera companies desperate to compete in a flooded market, and an attempt to trick consumers who don't know better (and screw with the results presented by "product selectors".)
REAL image stabilization uses a servoed prism inside the lens; the image is optically stabilized by sensing movement and adjusting the prism to correct. Current systems from Canon can compensate between 2 and 3 stops; dunno about Nikon's, but it is probably about the same. The systems work gloriously well, though they only compensate for movement of the LENS, not movement of the subject. A slow exposure will still be a slow exposure; if the subject is waving, their hand is going to be blurry. There's no substitute for light, sensor sensitivity (and low noise at high sensitivity), and maximum aperture (how "fast" the lens is. Smaller f-stop numbers are wider, and hence faster.)
FAKE "image stabilization", which Olympus (among others) are pushing- it only cranks up the sensitivity of the sensor to shorten exposure time. This only results in shorter exposures- and a LOT more noise, especially since most consumer cameras have tiny little sensors (the smaller each sensor pixel, the less light it collects, and the more it needs to be electrically amplified.) You can do this on *any* digital camera with adjustable ISO!
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The most frustrating example of this is the final putt on the golf course, the one which is about a metre away and you need minimum power.
You find yourself doing some random body shake to try to get it registering.
Half the time this ends up with the ball fucking off half a mile away and landing in the pond.
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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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Let's see, DS Lite almost always sold out in Japan. America has a low amount of handhelds that stay on the shelf. Wii is impossible to find in both countries with out a LONG wait outside.
Yeah, they should produce more games because the hype about the system and the titles they already have released and are releasing this year are a amazing. Barren? OH that's right when you compare it to the 360 or Ps3 it's.... wait it's still not barren it just has a lot less of the average crap on it. Yet the games that came out so far are really impressive.
Hmm yeah, Nintendo let's see you crank out the million of lackluster titles the other guys are producing, because I sure rather have a huge boat load of games that all play the same than innovative gameplay. It's obvious your console and handheld isn't already selling on it's own. Come on.
I've developed a way to get a perfect golf drive every time out of the Wiimote.
Sit down in your couch with the Wiimote in your hand just above your shoulder and next to your ear.
The IR should point toward the back wall not quite square. Swing the Wiimote STRAIGHT down to your thigh without changing your wrist angle. as long as you don't angle the Wiimote down with your wrist you can pretty much swing as hard as you want and you won't over swing.
Works for me everytime.
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IIRC, Mario Party comes out this week. That will cause a significant disruption in the american economy, as droves of people stay home and play with their Wiis. Nintendo must space such releases out, in order to safeguard our nation.
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.
What utter bullshit!P ath=23_85P ath=23_83
Having personally developed and packed a six axis MEMS inertial sensor (x,y,z acceleration, roll, pitch, yaw rate of rotation)into a 25x25x13mm cube (With my bare hands!!)potted in epoxy, with a rubber lining and a kevlar reinforced cord, and run 2 of these units for several hours at kilohertz rates logging onto a SD card, I can attest that 30mm cube MEMS sensors already do exist and have existed for over 5 years. Hell you can buy them in quantities of one from sparkfun:
http://www.sparkfun.com/commerce/categories.php?c
(while the sparkfun units are 51x51x23mm thats because they're avoiding many layer multilayer boards and low pin count microprocessors)
Note that 3 axis compasses are readily available as well:
http://www.sparkfun.com/commerce/categories.php?c
Now the devil in the details. MEMS accelerometers are noisy, and so are the MEMS rate gyros. They're about as good as your inner ear which operates on somewhat similar principles. As a result they track reasonably well for short periods of time but exhibit considerable drift over longer periods of time, just like you can guess your path over a short distance but end up going in circles in total darkness. A compass helps, but they get scrambled by magnetic fields from electric currents or pieces of ferromagnetic material. Inertial sensors (other than missile grade units which are orders of magnitude more sensitive and complex) only complement GPS and other absolute measurement systems. That's why the Wii has the optical sensor integrated in it as well.
Personally, I find the easiest way to make the short putts is to reach a threshold speed but increase the angular movement. Not like a real put which has fairly small angle. I use ~40 degrees with a slowish acceleration.
HTH.
Benedetto Vigna should read this report http://www.sciencemag.org/cgi/content/abstract/31
To fly we observed how birds did it, then instead, built wings as used in airplanes today, instead of wings like birds have.
Now if only I could get my hands on a Wii...
Views expressed do not necessarily reflect those of the author.