“I described the working of the Apple Motion Sensor (AMS), a feature of the PowerBook line of computers, in previous document called The PowerBook Sudden Motion Sensor”. As I noted earlier, my original reason for investigating the AMS was to fabricate some interesting programming examples for my forthcoming book on Mac OS X internals. The discussion of the AMS generated a substantial amount of interest — perhaps more than I had expected. It is quite interesting to observe how one’s fantasy is tickled by abnormal ways of doing the normal.” Read more here.
The Apple Motion Sensor As A Human Interface Device
Submitted by Hakime 2005-03-23 Apple 13 Comments
Fantastic technology of the sort that Apple is generally derided for for not inventing it first .
The example of creating a stable window that automatically rotates itself to stay level based on the orientation of the screen is pretty slick. It’s amazing what can be done TODAY with the technology included with the new powerbooks.
This is pretty much the same as IBM’s active protection system. The Windows preferences applet for that has a 3D laptop that rotates as you rotate your laptop. The idea is that the hardware can know when you’ve dropped your laptop and spin the disk down before it hits the ground – IBM shipped this early last year, and Apple are doing the same now.
But whether it is an Apple or IBM make sure it does have the protection before you drop the laptop.
Even after seeing it dozens of times I still get a kick out of the IBM when the guy drops what he thinks is a protected laptop and then his friend says “That’s not my laptop.”.
So the sensor must detect that the laptop is accelerating at 9.8m/s^2. Can it also test what direction? I’d think it can’t use direction alone, since you could drop the laptop upside down. Maybe it tries to keep track of gravity at the last stable (non-accelerating) position and read the turns from there?
I’m trying to think of ways to fool it. Like if my car could produce 1G in a turn or braking.
Would it be a good idea to sync the drive cache before spinning down the harddisk? Syncing needs a second or two, but can save some of your data. But if the crash happens before syncing is completed, it can cause even more damage. Still, I thing syncing is something to consider.
It would be nice to have this for Linux too.
I thought it just locked the drive heads down?
I wonder when apple actually starts to invent usefull things for their computers, instead of things that looks like cheap plastic objects
Welcome to the new century! Now PC makers make things that look like cheap plastic objects, and Apple makes things that look like expensive metal objects!
When you drop the computer, the device senses a sort of
weightlessness while falling. Orbit is all about this.
So, in the space station, the drive will spin down until
you come back to Earth?
Wait until you start playing with this as a toy and accidently drop your laptop because you tilt it 45o in your favorite airplane simulator game.
“So, in the space station, the drive will spin down until
you come back to Earth?”
The IBM APS detects if there’s some constant movement, and then reduces the probability of spinning down the drives, so in theory using it in space should be ok – though you’d be wise to just turn the damn thing off.
Regarding the IBM commercial, I still don’t think that it would be a good idea to drop your laptop even if it does have this protection. Even though this increases the probability of the HDD being ok, I don’t think this is going to help my LCD screen and even HDD cracking open when I drop the laptop.
The AMS, while being able to detect the direction of acceleration (how else would those slick apps work), probably only considers the magnitude of the acceleration when determining whether or not to park the drive heads.
If |a| = 9.81 m/s^2, give or take 10% let’s say, then the drive runs normally. If |a| = 0 m/s^2 (freefall), then that’s way off and the heads park, regardless of the orientation of the laptop. Dropped from 1 meter, that’ll take 0.45 seconds to hit the ground. Enough to write the cache to disk first? Doubtful.