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How the Wiimote Works
Posted by
Zonk
on Thu Dec 21, 2006 10:47 AM
from the little-tiny-marios dept.
from the little-tiny-marios dept.
The New York Times' 'How it Works' series touches on a remote with a twist: the Nintendo Wiimote. The article describes the micron-sized machines that make it work, displays cut-away graphics of the little white marvel, and rounds out the discussion with a breakdown of where the tech came from. From the article: "The controller's most-talked-about feature is the capacity to track its own relative motion. This enables players to do things like steer a car by twisting the remote in the air or moving a game character by tilting the remote down or up. 'This represents a fabulous example of the consumerization of MEMS,' the tiny devices known as micro-electro-mechanical systems, said Benedetto Vigna, general manager of the MEMS unit at STMicroelectronics, a leading maker of the accelerometers embedded in the controllers. (Nintendo itself declined to talk about the controllers' inner workings.) He said the motion sensors, using the technology that activates vehicle air bags, can accurately sense three axes of acceleration: up and down, left to right, and forward and backward."
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Two Weeks with the Wii 458 comments
In the 80s, kids of my generation cut their teeth on Super Mario Bros.. They went through high school with Mario Kart, and bonded with college friends playing Super Smash Bros. By 1999, though, the N64 had long since proven that Nintendo's dominance in American videogaming was over. The GameCube that followed was largely a disappointment. Nintendo failed to interest third party developers, and frustrated fans with long-delayed chapters of the Mario, Zelda, and Metroid franchises. Coming into this no-longer-next generation of consoles, Nintendo announced they were aiming for a Revolution, and then confused everyone by renaming it Wii. Their actions left a lot of people wondering if the company still had what it took to compete with committed powerhouses like Microsoft and Sony. The launch lineup is kind of tepid, and the controls really do take some getting used to. We've already established that they're not aiming to compete in the graphics race. So what is the console really like? Why is it selling so quickly? What does it have to offer? I've had two weeks to find out. Read on, so that you can get a feel for the system you'll definitely be playing (if not owning) at some point in the future.
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Apple: DarwiinRemote - A Wiimote Frontend for OSX 74 comments
jeckil writes "DarwiinRemote is a tiny piece of software which reads data from and sends data to Nintendo Wii Remote. It detects all 3 axis sensors, all buttons (except power). You can modify which controller LED indicator is on, and send force feedback. Right now it only supports a basic front row control scheme but they should be releasing a better version in a few days. All the source code is available and compatible with latest version of xcode. One can only wonder ... If the latest apple rumor turns out to be true, things could get very interesting for apple. Someone has already released a modified version of this app. It seems there have been some problems detecting the remote so an alternate version that uses the Wiimote's sync button has been released."
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Wait... (Score:5, Funny)
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Re:Wait... (Score:5, Funny)
That's why they should have called it something super-awesome like Axis of Threevil.
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Then again, so does the WiiMote.
The article does not add anything new to our knowledge of how the nifty little toy works, and it does leave out the fact that the wiimote track rotation as well as movement.
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You might want to have your sarcasm detector checked.
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The accelerometer returns acceleration along 3 directions, with relation to the remote. This allows it to detect tilt by figuring out which way gravity is, giving it 3 rotational axises.
The POINTER system can determine a) how far off in what direction the sensor bar is from where the remote is pointing, b) how far away from the sensor bar the remote is and c) The rotation of the remote with respect to the sensor bar.
THis means the wiimote basically has two ways to d
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The accelerometer returns acceleration along 3 directions, with relation to the remote. This allows it to detect tilt by figuring out which way gravity is, giving it 3 rotational axises.
How can you infer gravity's direction purely from the local linear accelerations? If your acceleration vector is , okay, you know which way gravity is. But what if your acceleration vector is ? Which component is due to me moving the WIimote and which component is gravity?
Also:
The POINTER system c
CORRECTION (Score:2)
The first should be [0,0,-9.8] and the second should be [15,15,15].
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The fish thing? That's not really a calibration. That's just telling you to move *its* assumed pointer location onto *its* objects. That has nothing to do with whether *its* assumed pointer location is where you're really pointing.
Little low-tech for SlashDot, eh? (Score:3, Insightful)
C'mon, "editors"...this is SlashDot, not Time. Most people here could probably have written that article blindfolded. How about a couple of real tech articles today?
Not troll (Score:3, Insightful)
Time is very dumbed down, and uses slang my middle school English teacher wouldn't allow. That's for non-technical articles.
The NY Times article doesn't tell us anything we didn't already know.
Re:Not troll (Score:4, Funny)
That's not very nice. I mean they named you as "Person of the Year" after all, didn't they?
Parent
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Air bags? Perfect! (Score:5, Funny)
Nintendo is using their wiimote technology to determine when the wiimote flies from the users hand, and will now deploy an airbag before striking your HDTV.
Please return your wiimote for the new version with the wiirbag.
only three axis? (Score:4, Funny)
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But the latter might be more appealing to people whom like to watch FOX News etc. "The Wii gives you motion tracking, but does it give you FREEDOM?"
Then again, Americans might object to getting their freedom from Japan...
Analogies rule!!! (Score:5, Interesting)
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and zelda, and Valve games....
and..
oh alright, you win.
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simplified "how it works" (Score:5, Funny)
I thought the Wiimote worked like this:
If you see a monster, throw the Wiimote directly at the monster. Depending on your aim, the monster will die in a shower of bright sparks and crackly noises, or the monster will hurl various objects back at you such as books, chunks of plaster, ceiling fan blades, or your little brother's eyeball.
Imagine the possibilities (Score:3, Funny)
No disassemble!! (Score:2, Funny)
Didn't Live Up To The Hype (Score:2, Informative)
First, the Wiimote isn't an absolute pointing device. It's all relative to the Wiimote bar you place near your TV. Everything is relative to that device, so you are never actually pointing accurately at anything on your screen.
Second, the Wiimote has accuracy/responsiveness issues. Not sure if it is interference from bright lights or some other type of wireless/electronic devices. There are
Re:Didn't Live Up To The Hype (Score:5, Informative)
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Not informative (Score:2)
If you stand close to the TV -- not so close that it goes haywire, but close -- you'll see that it thinks it's pointing way off, depending on how you point, and usually in the vertical direction it's the most severe. And unlike the sibling poster said, this
Re:Not informative (Score:5, Interesting)
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Well, that's my point. You *shouldn't* have to. I completely agree with allowing the simple "above or below" quick setup. My complaint was that it doesn't allow you to provide it more information so that it can use a different algorithm, if you desire, that is more accurate for your particular screen. And the "consistency between screens" isn't necessarily good. It means if I have a smaller-than-usual screen (a pitiful 23'', poor me) I have to keep
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Re:Didn't Live Up To The Hype (Score:5, Informative)
I found that made a huge difference.
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Re:Didn't Live Up To The Hype (Score:5, Informative)
I don't think it ever was lauded or presented as an absolute pointing device prior to its release, but it is a very good ubiquitous pointing device and not simply a one trick pony as something like the Zapper was. As stated by others before me, this is because the sensor bar emits the IR which the wii-mote triangulates its pointing position from. It definately works best on the top of the TV, IMO. Ideal setup can vary depending upon whether you are typically sitting or standing, how high your TV is relative to the ground/seat, etc. Calibrating it is important too -- in my mind, that's one of the things that killed Red Steel - you can only calibrate at the very begining of the first level and not from the pause menu while pointing is an essential part of the controls. In Zelda:TP, you can play entirely without using the pointer and it still has a more advanced calibration option than the beginning of Red Steel available at all times (if only you could turn down the tingling fairy sound).
It would not be possible to have an absolute pointer that would work on all TVs; they would have to actually sell a Wii TV (a Wii-V?) with the IR beams behind the screen to make an absolute pointer. The reason the Zapper and other light guns worked as something like an absolute pointer is because the tech was different, and as I understand it will not work on some modern TVs (I can't recall if its LCD or Plasma). When you pulled the trigger on the Zapper, the screen flashed black for a frame, and the area around the target sprites flashed white after that to indicate a target. The photo-receptors in the Zapper would detect that different to determine a hit or miss. Would you really want the screen flashing right with every shot in any modern FPS? The problem with using something like an invisible later pointer is that TV screens are not flat, and are usually convex. To do a reflective pointer you would ideally want a concave screen with the player at the focal point. By using IR and having each Wii-mote figure out its own position, you don't have to worry about different controllers interfering with each other's signals, etc.
Second, the Wiimote has accuracy/responsiveness issues. Not sure if it is interference from bright lights or some other type of wireless/electronic devices. There are times where you are having to repeat the same motions over again because the Wiimote isn't registering.
If you're having accuracy/responsiveness issues with the pointer, your most likely culprits are 1) other bright lights (including sunlight) in your gaming area 2) Other heat sources that aren't lights in the gaming area (i.e. laptop with running harddrive on the coffee table) 3) possibly reflective surfaces, but doubtful. If you aim your Wii-mote away from the screen and happen to pass another heat source like a candle or laptop, it may temporarily focus on that for triangulation, causing all sorts of problems, so keep your gaming area free of IR sources that can distract the remote. Lights should only be a problem if they are also a significant heat source (incandescent bulbs), and darkened rooms are better for gaming anyway.
I haven't had any obvious problems with Wi-Fi, but it and Bluetooth do operate in the same range, as do most cordless phones. If you're having response problems regularly, try changing the set channels on your Wireless router and/or cordless phones.
As for response issues with other motions, I have occasionally noticed some problems (like with batting in Wii baseball), where the bat seems way off, but if you go back to a base position and restart your motions, it usually comes out just fine. One of the tricky parts to motion recognition is determining which motions were deliberate and which are casual motions not meant to take an action. I much more often accidentally do something with a casual motion than have actions go undetected.
Parent
And the firmware is available too.. (Score:2)
Motion or angle? (Score:3, Insightful)
It seems to me that they must be separate, at least a little. You can walk away with a Wiimote, far out of bluetooth range, turn it however you like, bring it back... And the console will still sense its orientation precisely. Location? Games that use that sometimes get out of sync so you have to wave the Wiimote around a bit to get them better calibrated.
So I'm pretty sure that's a separate feature, to say nothing of the additional component of the CCD pointing at the IR sources above your TV to give you a pointing device.
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There is a reason for that
The Force of Gravity will always register as an (aproximately) 9.81 M/(s^2) acceleration to the acclerometers inside of the Wiimote; this means that you should be able to tell it's orientation in comparison to the ground pretty easily.
I'm a bit confused. The ability of the Wiimote
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Unless, of course, I'm accelerating it such that the vector appears equal in all directions or something.
Re:Motion or angle? (Score:4, Interesting)
The Wii-mote has accelerometers on it. These sense forces applied to it (gravity included), and their combined output is a vector indicating the direction and modulo of the resultant acceleration. Assuming you're standing still, you'd only be subject to the force of gravity, and by definition it always points to the ground. So do a few vector computations and you know the orientation of the Wii-mote. There is a problem with a `blind axis' (rotation in the same axis as gravity can't be detected), but ignore that for now.
On the other hand, if you want to estimate position, here's what you have to do: given an initial position, read the accelerometers, subtract the effect of gravity from the acceleration vector (harder than it seems, since the Wii-mote could be pointing anywhere, really), which then gives the `real acceleration' of the system. Now integrate this once to obtain velocity, and again to obtain position. There's just so much room for error here, that I don't know where to start. Limited accelerometer resolution, poor A/D converters, temperature drift, numerical accuracy issues, you name it. Integrating measurements (not only that, but integrating twice!) is just a recipe for disaster. Then there's a fundamental limitation to accelerometer devices: rotations can't really be distinguished from translations. Just think about it -- a given resultant acceleration vector could be the result of pointing the Wii-mote in any given orientation, added to a specific acceleration in a specific direction. You just don't have enough information to distinguish between the two -- not with accelerometers alone, at least.
Hope that helps.
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The one missing feature (Score:2, Informative)
The most obvious use (to me) for such a feature would be to have the Nunchuk pan the camera left and right as you