Motion and gaming collide

Nintendo's white wonder, the Wii, is doing huge business, and more people than ever are picking up a controller these days to flail their arms in a game of Wii Sports or do their morning stretches with Wii Fit. Everywhere you look, there are girls and grannies playing the Wii just as much as, if not more than, teenage boys. But for all the money that the system has been raking in, there are still some flaws with Nintendo's console: the most prominent of which has to be "Waggle" syndrome.

Even though the Wii is the most advanced motion-controlled gaming console ever released, the technology inside the remote is surprisingly basic and already dated. As a result, motion-controlled elements of most games have involved little more than "waggling": minimal gameplay actions that respond to loosely-defined movements and really don't function as effectively as they could. Small motions and big motions are hard to differentiate, and the remote isn't capable of tracking where it is in 3D space. Complicated 1:1 control—when the remote directly relates to its digital equivalent in 3D space—has proved too much for the standard Wii remote. Look no further than "Lazy Wii Sports" for proof at hand.

This being the case, it seems logical that Nintendo's next step towards improving the Wii would be to fix its limited motion control, and offer gamers and developers a much more accurate 1:1 correspondence between controller motions and on-screen actions. That very evolution was unveiled at this year's E3 convention in Los Angeles in the form of the "MotionPlus," a small controller add-on that vastly improves the remote's ability to recognize motion and, ultimately, to power more involving and immersive games.

1:1 sword-fighting is one gameplay possibility that just can't be done with the stock Wii remote.

The announcement of MotionPlus came and went with little fanfare in the hardcore community, though the early preview of the follow-up to Wii Sports, Wii Sports Resort did showcase some genuinely more advanced games. These games, which included the likes of frisbee and sword-fighting, have been made possible only by MotionPlus. Much ado was made about how little information was given to developers prior to the E3 unveil, but little attention was given to the actual tech inside of the new add-on and to the effect it could have not only on the Wii but on the way motion control is used for gaming as a whole.

Technically speaking, the MotionPlus isn't a stand-alone device that trumps the original Wii remote, but rather a crucial piece in the ever-evolving puzzle of Nintendo's motion-control strategy. The new device adds a gyroscope to the equation, but what exactly does that do for the remote and for motion-controlled gaming at large? To answer that question, we have to turn to InvenSense, a third-party motion technology company specializing in motion-sensing solutions, and the brains behind the gyroscope at heart of the MotionPlus. Ars had the chance to speak with Joe Virginia, Vice President of Wireless Business & Corporate Communications at InvenSense, and he dished the dirt about the new add-on and what this technology means for the future of motion-controlled gaming.

From the outset, InvenSense worked diligently to provide Nintendo with a solution designed to solve the "waggle" problem. The company and Nintendo came together thanks to "a 'disruptive MEMS (Micro-Electro-Mechanical Systems) technology," explained Virginia. "This value proposition was embraced by Nintendo. We don't manufacture the [MotionPlus] accessory—there's been some confusion about that—but we offer a multi-axis MEMS gyroscope to Nintendo that, when combined with the other sensors and the sensor bar, offers a true six-axis motion controller experience."

The tech it takes to swordfight

That six axis motion controller experience is exactly what Nintendo was after with the deal, which has had InvenSense providing millions of the chips in preparation for the spring launch of the peripheral.

The original Wii remote features a single accelerometer chipset: the ADXL330, with three-axis filtering caps and a power decoupling cap. The chip gives three-axis sensing in a small, low-profile package (4×4×1.45mm), and it draws very little power with 180µA at 1.8V and single-supply operation of 1.8 to 3.6V with a shock survival capacity of 10,000g. As tight a package as its offers, though, the accelerometer is only capable of measuring movement velocity along the X, Y, and Z axes—only linear acceleration without rotation. The problem is that acceleration due to gravity can easily be confused with linear motion when using the device. And though the accelerometer can track gravity, it can't measure horizontal rotation. This results in a jittery representation of the interpreted data which, when combined with subtle hand movements, makes for an oft-inaccurate picture of what is going on with the remote. This is why basic attempts at 1:1 representation with the original Wii remote, such as the baseball bat in Wii Sports, tend to be limited at best.

A diagram of the IDG-600, the InvenSense chip used in the MotionPlus.

Gyroscopes, on the other hand, measure rotation directly. These sensors are very responsive and don't amplify hand jitter, but cannot respond to the linear movement that accelerometers specialize in. When a gyroscope and an accelerometer are combined, though, the pair of sensors affords the ability for highly accurate representation of the control device in 3D space. The technology isn't flawless—hardware and software smoothing will still be a factor in true 1:1 representation—but it's more than good enough for a certain developer to finally make that certain long-awaited sword fighting game involving sabers of light.

The IDG-600 gyro, which is the particular chip that InvenSense has provided to Nintendo for the MotionPlus, uses two sensor elements with novel vibrating dual-mass bulk silicon configurations that sense the rate of rotation about the X- and Y-axis. This results in a unique, integrated dual-axis gyro with "guaranteed-by-design vibration rejection and high cross-axis isolation." The chip also has an integrated means to "eliminate the need for external active components and end-user calibration."

Gyroscopes have long been used in various applications. Getting that technology shrunk down and cost-effective, though, was the real battle for InvenSense. "When you think of gyroscopes today, though, especially with regard to heading information, they're around $300,000 and are capable of accuracy of ten-thousandths of a degree per hour so that a 747 after an eleven hour flight can land where it's supposed to land," explained Virginia. "Game controllers, such as what Nintendo has selected, don't need that kind of accuracy. What they were looking for something in the area of one-tenth of a degree per second. [The IDG-600 gryo in the MotionPlus] measure up to 1500 degrees per second; it offers accuracy and full-range motion. We worked towards [a cost of] $1 per axis."