Hard Drive shock protection

[scitobor 617]

I'm working on a project in which I will be mounting a desktop computer on a lawn mower to control it. I'm worried that I will be running the risk of damaging the hard drive from all of the vibration. Has anyone ever killed a hard drive from vibration? How long and intense can vibration be before there is serious damage? Also, what can be done to protect a hard drive from vibration, I've found a few ways but I want to know what others are out there.

This website has a description of how hard drives are normally damaged.

-Alan

[Adam Richards]

A few questions before any real answers can be given:

1) What speed (in RPM) is your hard drive? Lower is better for this; SCSI is NOT A GOOD IDEA. Is flash media an option? Several different *nix distros can fit on a 2gb card, and vibrations wouldn't even bother the card.
2) How strong are the vibrations from the lawn mower?
3) How much would you be running this?

[sciguy125]

egg shock protection

[scitobor 617]

Originally Posted by Adam Richards

1) What speed (in RPM) is your hard drive? Lower is better for this; SCSI is NOT A GOOD IDEA. Is flash media an option? Several different *nix distros can fit on a 2gb card, and vibrations wouldn't even bother the card.

Well it is an IDE hard drive, I think 7200 RPM. Infact I will be running Linux on it but I have not considered flash storage. So far I've just been using parts that I could find laying around my house and school. I have a few old CDrom drives, maybe I could make a LiveCD. Maybe vibration would be less of an issue for a CD drive. How much do 2gb flash cards cost and where can I buy them?

Originally Posted by Adam Richards

2) How strong are the vibrations from the lawn mower?

I don't know how strong the vibrations are. How could I go about measuring it?

Originally Posted by Adam Richards

3) How much would you be running this?

Well my end goal is to have this system cut my lawn autonomously (I've really gotten lazy about cutting the grass) so it will be run for about an hour at a time.

[Ryan M.]

Originally Posted by scitobor 617

Well it is an IDE hard drive, I think 7200 RPM. Infact I will be running Linux on it but I have not considered flash storage. So far I've just been using parts that I could find laying around my house and school. I have a few old CDrom drives, maybe I could make a LiveCD. Maybe vibration would be less of an issue for a CD drive. How much do 2gb flash cards cost and where can I buy them?

CDs would probably be more sensitive to vibrations, (think of a CD player without skip protection) but they won't actually get destroyed. Because it's likely that once the base system and the lawn cutting program load you won't need to be retrieving more data, it would probably work fine. (Esp. if the cdrom spins down after that.)

Interesting idea. I might try that too...

[Greg Needel]

I had to do this on our DARPA grand challenge car. after much review we opted to go for solid state flash drives, although if that is not an option (cost, memory size) defiantly use laptop hard drives as they are much less affected by vibration.












edit: 1000th post

[Tristan Lall]

Originally Posted by Adam Richards

1) What speed (in RPM) is your hard drive? Lower is better for this; SCSI is NOT A GOOD IDEA. Is flash media an option? Several different *nix distros can fit on a 2gb card, and vibrations wouldn't even bother the card.

Flash is definitely a good idea, in fact much better than a hard drive, for something like this. Think of read/write heads moving a couple thousandths of an inch above the surface of the platters, containing data which you need, and then think if you've ever seen a smooth-running lawnmower (or any smooth-running 1-cylinder engine, for that matter). It's similar with CDs; by getting my read heads out of alignment on one drive (I was adjusting it because it wouldn't read reliably), I managed to have it cut concentric rings in a disc, because the head was dragging on the surface. You will too, if you try to retrieve data from a CD, only they won't be so evenly spaced, as the drive seeks back and forth over the entire surface, and bounces wildly.

Windows 2000 fits on a 2 GB card too, provided that it's properly pruned down (to leave a couple hundred MB for swap space); you might need to install to a larger drive (which you have), delete extra stuff, then image it to a card. Then again, Linux works too, if you prefer.

In any event, any computer store will carry (or be able to get) the appropriate size of compactflash card; compactflash is pin-equivalent to ATA, but uses a smaller connector, so a simple pass-through adapter will allow it to be used with any common motherboard through the 40 pin connectors. See here for the card, and here for the adapter for example.

Also, I can't help but correct this: SCSI is a bus specification. It is not an indication of shock resistance. Modern SCSI drives are often built with high spindle speeds, but older ones can be had with much slower spindle speeds; I've worked with a 4.3 GB, 4200 rpm SCSI drive, and a brutally slow 200 MB SCSI drive from the mid 1990s. Though I agree that it seems sensible enough that peak spindle speed and vibration resistance may be linked, I'm not sure that the correlation is significant, especially compared to other characteristics of the drives' designs.

Originally Posted by Greg Needel

edit: 1000th post

On the ArsTechnica Forums, they have a procedure for dealing with people who brag about multiples of their thousandth post. Ask about the "DoD" in that forum's "The Lounge" section....

[sciguy125]

I realize that if your looking for vibration resistant media, flash would be your best bet. However, I'm a little weary about using flash as the primary storage on a computer. My concern is wearing out the cells. Flash can only go through a finite number of read/write cycles. For something like a camera, it's fine because you'll usually fill up the card before erasing it. A computer however, will be constantly changing data. A file that's rewritten very often (maybe a log), it would wear out the flash very quickly.

[Tristan Lall]

Originally Posted by sciguy125

I realize that if your looking for vibration resistant media, flash would be your best bet. However, I'm a little weary about using flash as the primary storage on a computer. My concern is wearing out the cells. Flash can only go through a finite number of read/write cycles. For something like a camera, it's fine because you'll usually fill up the card before erasing it. A computer however, will be constantly changing data. A file that's rewritten very often (maybe a log), it would wear out the flash very quickly.

That's always been a concern with flash memory technology, but since he only intends to use it for an hour a week, and because most of the activity should be taking place in RAM anyway (since there's not really much need to page data in and out, except to load it the first time it's needed—and even that is only a read), I doubt that he'll see any trouble, unless he's writing huge amounts of data in his log files. His usage pattern is (presumably) so different from that of a normal computer, that usual caveat shouldn't really apply. In any event, flash memory tends to have at least a few hundred thousand rewrites per cell (on average), and some good-quality, modern cards are reputed to be capable of millions of rewrites.

[ConKbot of Doom]

Do you really need a full computer? Or a full computer on the mower? what do you want to do with the mower and the program? Could you get away with something like a microcontroller? If that wouldnt be enough, you could take a linksys WRT 54G wireless router, which runs on linux and has many other 3rd party firmwares, and is open-source also. Add a SD card, and use the GPIO's on it to interface to the mower. http://kiel.kool.dk/

Plus then you have wifi built into it, and you could do neat stuff like call the mower in if the weather turns bad... etc..

EDIT: just to get you thinking... http://yasha.okshtein.net/wrt54g/

[sanddrag]

Would something like an iPod work?

[ConKbot of Doom]

Originally Posted by sanddrag

Would something like an iPod work?

Do Ipod's really have that much protection around the drive? They didnt look like it from the things Ive seen online when they are opened up.

One thing to remember about shock absorbers, if you do decide to go the route of using a full computer, they need to absorb the shock, not convert it into oscillations. A lot of the things that I have seen online for hard drive shock absorbers involve rubber bands. They end up having the hard drive there oscillating after the bump, which is almost worse (if not, actually worse) than the initial bump. The shock absorbing mechanism in that video in the first post was amazing, the drive moved down and back up, once and stopped. That is what the shock absorber should do.

[mechanicalbrain]

Well the new nano is actually a flash drive and I seem to remember (can't place my finger on where) reading about someone rigging a Ipod to run an operating system. Anyways, have you actually tested if the vibrations will cause problems. As it was mentioned before, a hard drive probably wont be damaged by the vibration unless screws come undone (not likely). If it does start to skip on you you might want a foam. Try running your computer and see what a hard drive will take before it skips (I know Ive dropped computers while they were running and had no trouble but the constant vibration might be an issue).

[[527]phil]

Originally Posted by mechanicalbrain

Well the new nano is actually a flash drive and I seem to remember (can't place my finger on where) reading about someone rigging a Ipod to run an operating system. Anyways, have you actually tested if the vibrations will cause problems. As it was mentioned before, a hard drive probably wont be damaged by the vibration unless screws come undone (not likely). If it does start to skip on you you might want a foam. Try running your computer and see what a hard drive will take before it skips (I know Ive dropped computers while they were running and had no trouble but the constant vibration might be an issue).

http://digitalmedia.oreilly.com/pub/...ks.html?page=3

you mean this?

But I don't advise ueing an IPOD as a bootable drive becase those hard drives are only rated for 20,000 hours or so

[scitobor 617]

Originally Posted by sciguy125

I realize that if your looking for vibration resistant media, flash would be your best bet. However, I'm a little weary about using flash as the primary storage on a computer. My concern is wearing out the cells. Flash can only go through a finite number of read/write cycles. For something like a camera, it's fine because you'll usually fill up the card before erasing it. A computer however, will be constantly changing data. A file that's rewritten very often (maybe a log), it would wear out the flash very quickly.

I've been trying to stay away from flash media because of the read/write limitations and the fact that while the computer is not driving the lawn mower it would make a decent desktop PC. But since I have not really started the software development yet, I can design to minimize reads and writes, which should be farely few anyways.

Originally Posted by ConKbot of Doom

Do you really need a full computer? Or a full computer on the mower? what do you want to do with the mower and the program? Could you get away with something like a microcontroller? If that wouldnt be enough, you could take a linksys WRT 54G wireless router, which runs on linux and has many other 3rd party firmwares, and is open-source also. Add a SD card, and use the GPIO's on it to interface to the mower. http://kiel.kool.dk/

Plus then you have wifi built into it, and you could do neat stuff like call the mower in if the weather turns bad... etc..

EDIT: just to get you thinking... http://yasha.okshtein.net/wrt54g/

Well the main reason for a full sized PC is that I wanted to beable to have remote control over the internet with streaming video and a MicroATX PC seemed like a good control system. I looked into using a microcontroller but it just seemed more advantagous to build PC for ~$300 that does what I want and more than settle for a ucontroller that did most of what I want for 1/3 -1/2 the cost of the PC. Also, with a PC I can keep adding sensors and do all kinds of image processing until my heart is content. May not have been the best choice but thats what I've got. Wow that Linksys RC car is pretty sweet... now that would be awesome on a Nitro RC car!


As I look at the prices of flash media, laptop harddrives are starting to look very attractive. I found the specifications for a laptop harddrive and I don't think my lawn mower will approach the maximum shock or vibration rating but I need to be sure, any ideas on how to measure it?