[Tech] Apple's Sudden Motion Sensor


This guy crafted some interesting visualizations and hacks based on a sensor built into Apple PowerBooks.

Apple added a feature called Sudden Motion Sensor (SMS) to the PowerBook line in early 2005. The sensor attempts to prevent data loss by parking the heads of an active disk drive after detecting a "sudden motion", which could be due to strong vibrations or a fall.


AMS Visualizer is a logical graphical extension of the amstracker command-line tool. It displays a 3D image of a PowerBook 15 that appears to "hang" in space.


This example creates a window displaying a bicycle wheel. The window is "stable" in the sense that if you rotate the PowerBook left or right, the window compensates by rotating itself by an equal amount in the opposite direction in an attempt to remain in its original orientation with respect to the ground. The bicycle wheel rotates too — independently of the window.


The "perturbed desktop" is hard to describe, and perhaps impossible to justify, even for a book example. It could be thought of as roughly the Stable Window concept applied to the entire graphical user interface, and then made unstable via some constraints. Now, nobody needs (hopefully) such "stable" windows in real life. Nevertheless, it is interesting to note the type of visual operations that are possible in Mac OS X.


Danyel said…
My Toshiba M200 has had similar stuff since mid-2004. But, of course, they never put an API on it. So you can't actually get to the niftycool sensors and do anything interesting with them.
Anonymous said…
What do you mean "they did not put an API on it"? Every such sensor *has* an API. The question is whether the vendor has published that API or not. For your information Apple doesn't publish anything about the PowerBook sensor either. So as per your definition "Apple hasn't put an API on it" either. This guy has REVERSE ENGINEERED the PowerBook sensor. It would be similar effort to reverse engineer any other sensor like your Toshiba or the ThinkPads.

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