Laptop computer tech "drop protection"

Scott Johnson · **Posted:** Wed Jun 29, 2005 5:49 pm

So lots of the new computers claim to be able to "sense" a drop and act accordingly (parking the heads on the hard drive). Does anyone know the nature of the accelerometer they are using? Could it be tapped into for basic data acquisition? Just strap the laptop to the passenger seat and drive, all the while it records your activities?

Scott

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Heard of it done on a Powerbook, but not (yet) on a Thinkpad.

There are $20 accelerometers and free serial port data-acq systems. Always wanted to build one.

Maybe it's time to get back into macs.

Here's one page. Google "Powerbook accelerator hack"

http://life.firelace.com/archives/2005/ ... werboo.php

Kevin Hoff · **Posted:** Wed Jun 29, 2005 10:22 pm

I wonder if we could get some info about the hardware interface on a Thinkpad from any of the Lenovians...

--Kevin H.
(Has an R51 at home -- built-in data acquisition would be pretty cool!)

George Bright · **Posted:** Thu Jun 30, 2005 7:28 pm

It would bee cool if the computer would let out a scream on the way down when dropped.

I have my doubts that the accelerometers set up for two axis data collection.

joedobner · **Joined:** Thu Apr 01, 2004 3:15 pm **Posts:** 85

If it's airbag-like, it's probably just a momentary switch that trips if acceleration beyond a certain threshold is detected, which wouldn't do much good.

On the other hand, a trackpoint could be used to make a ghetto accelerometer. If one were to machine a vertical sleeve with a small weight at the top and slip it onto the trackpoint's post, you could use Java/Visual C++ to intercept the mouse events and figure out how fast you were accelerating.

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

Or you could just save a lot of hassle and energy. Spend $300 and get a really cool toy.

http://www.gtechpro.com/rr.html

This is on my Xmas list

Dustin Fredrickson · **Posted:** Fri Jul 01, 2005 10:40 am

joedobner wrote:

If it's airbag-like, it's probably just a momentary switch that trips if acceleration beyond a certain threshold is detected, which wouldn't do much good.

The sensitivity on the "drop protection" IS adjustable, at least in 3 increments, so there's got to be SOME sort of analog capability to it.

Of course, I think a GEEZ is still a better option (and if anybody were really interested, mine could probably be had for a reasonable price...)

Chuck Frank · **Posted:** Fri Jul 01, 2005 10:55 am

Dustin Fredrickson wrote:

joedobner wrote:

If it's airbag-like, it's probably just a momentary switch that trips if acceleration beyond a certain threshold is detected, which wouldn't do much good.

The sensitivity on the "drop protection" IS adjustable, at least in 3 increments, so there's got to be SOME sort of analog capability to it.

Of course, I think a GEEZ is still a better option (and if anybody were really interested, mine could probably be had for a reasonable price...)

Now if someone would only update the software for the Geez so it ran on anything more modern than an abacus...

Dustin Fredrickson · **Posted:** Fri Jul 01, 2005 11:07 am

Chuck Frank wrote:

Dustin Fredrickson wrote:

joedobner wrote:

If it's airbag-like, it's probably just a momentary switch that trips if acceleration beyond a certain threshold is detected, which wouldn't do much good.

The sensitivity on the "drop protection" IS adjustable, at least in 3 increments, so there's got to be SOME sort of analog capability to it.

Of course, I think a GEEZ is still a better option (and if anybody were really interested, mine could probably be had for a reasonable price...)

Now if someone would only update the software for the Geez so it ran on anything more modern than an abacus...

The interface is quite dated, and the parallel port key attachment is antiquated, but there IS a driver to get it to work with at least Windows 2000 (haven't tried XP) and it still get's the job done.

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

For those looking for an accelerometer or yaw rate indicator.

See this inexpensive product with video.

Click Here!

DickRasmussen · **Posted:** Fri Jul 01, 2005 2:58 pm

Dustin Fredrickson wrote:

The interface is quite dated, and the parallel port key attachment is antiquated, but there IS a driver to get it to work with at least Windows 2000 (haven't tried XP) and it still get's the job done.

FYI the GEEZ XP driver works for me. The only problem I had when using it with a new (in 2002) laptop was getting the Palm serial port to usb adapter to work. Ended up buying a Belkin which works.

Rick Butters · **Posted:** Fri Jul 01, 2005 8:39 pm

My G-cube works fine with windows XP, although I did have to download a different driver. I use a Palm as my intermediate interface.

joedobner · **Joined:** Thu Apr 01, 2004 3:15 pm **Posts:** 85

Dustin Fredrickson wrote:

The sensitivity on the "drop protection" IS adjustable, at least in 3 increments, so there's got to be SOME sort of analog capability to it.

Maybe. I doubt that 1G of acceleration alone would be enough to cause a head crash, but that 15G acceleration when the laptop stops when it hits the floor is. It could be that it's the length of time that the switch stays tripped is what the sensitivity threshold considers, in order to prepare itself for impact. Then again, the heads could be quick enough that they could park right when the impact was detected.

I just got a new T42 and I'm intensely curious, but I bet the design of the device is somewhere in our patents database.

JamesFeinberg · **Posted:** Tue Jul 12, 2005 11:34 am

The accelerometers used in most (all?) laptops are like these.

They do indeed have an analog output and are fairly sensitive. I played around with a couple of these about a year ago and they could form the basis for a data acquisition system.

In the case of the Thinkpads, there is a system driver (shockprf.sys) you can access to tap into the motion data. While I never found an API released by IBM (any other manufacturer), I was able to read the data by some fairly crude software hacking. If you want the super gory details, I can dig up my old code and notes and pass them along.

Jim

DickRasmussen · **Posted:** Tue Jul 12, 2005 1:56 pm

James,

Are the laptop sensors different from what is "probably" used in GEEZ? I assumed Byron used "airbag" oriented accelerometers but I literally don't have any basis for that assumption and have no idea what sensors are available. The reason for asking is that obviously whatever GEEZ uses work so if the laptop uses the same approximate "versions" . . . .

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