First let's recap how the wiimote's accelerometers work. They read motion based on the force put on them. This data is reported as a number on one of 3 axis. For instance a quick move to the right could read as x=7, a slow one x=3. The greater the force the larger the number. Left and right movement is read as x, forward and back y, and up and down z. For each axis one direction is a positive value and the other negative. In the case of x right is negative left is positive. With this you can make gestures that are as simple as a quick move to the right or as complicated as the shapes in a game like SSX Blur.
Tilt is done using the force of gravity. When you tilt the wiimote two of the 3 values change do to the pull of gravity. The wiimote uses this data to tell what angle it is being held at. It reports this as one of two angles, pitch and roll. It can't do yawn because gravity doesn't change when you tilt the wiimote left and right. Up until recently I thought this was a great way to read tilt.
Even though tilt controls tend to work well the way they are they still have there limits. The lack of yawn is one. The fact it uses the accelerometers is another. The force of gravity can not be used when the wiimote is in motion meaning you can not have both tilt and normal acceleration at the same time. A great example is Wii Sports baseball. The game uses tilt to make you think the Wii can do 1:1 motion but any quick motion triggers a swing. The Wii is just using tilt until it sees a quick motion and this triggers the swing. It can't determine the wiimote's angle while it's in swing because it can no longer feel the force of gravity. You can see this in Warioware was well in the samurai game. If you tilt the wiimote quickly the sword disappears for a second up till it can feel the pull of gravity again. You may also notice this in racing games if you turn the wiimote quickly. What Wii need is a something else to handle tilt.
This is where Wii Motion + comes in. It is a gyroscope. A gyroscope is a device that can determine it's orientation by resisting gravity. Using this the wiimote can always tell how it's tilted. To make things better it can also adjust the accelerometers so they know there being tilted and can discount the pull of gravity. This means the wiimote and always know how it is being held and moved! Similar systems are used in inertial navigation systems.
Now there are many thing that can be done with this setup. Sword fighting is just one of them. Now games like baseball, golf and tennis can read both the speed and angle of your swing like never before. Your passes in Madden can now take your angle into account like never before. Why not have a free throw system in an NBA game that requires you to have just the right angle and power to make the shot. It may even be possible to use the wiimote like a gyroscopic mouse and remove the need for the sensor bar. There is little doubt that this will be big for the Wii. If it will mean true 1:1 however I'm not fully convinced.
The accelerometers may still not be good enough to know distance the player moved. The wiimote knows how much force was applied to it but will that be enough to know how far it moved. If you look at the sword fighting in Wii Sports Resort you can see that the angle the sword is held at still determines where it is held. I have yet to see some one hold a sword in front of them and up at a 45 degree angle. If the sword is held at a 45 degree angle the Mii holds it up at a 45 degree angle even if the player holds it out strait.
Even though this is a big steep for the Wii I can not lie and say it is perfect. I started this feature not to make the Wii look bad but to explore it's potential. To do that I can not ignore what it can and can not do. Rest a sure what it can do is impressive but I don't want people to have unrealistic expectations. For now I say the Wii still can not to 1:1.
Here is a video that should help explain things (Thank you -VashTS):
Note this is the first Wii can't do 1:1 in this blog. Others can be founded on my other blog.
The accelerometers are better then I thought. The Wii can finally do 1:1.