Hard Drive shock protection

[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?

[Smrtman5]

For measuring shock, like bumps, maybe an accelerometer would work, like something you might use in physics. Hooked up to one of those vernier lab pro computer things, you could probably get a fancy graph and find the shock force. I guess that could work for vibrations too maybe? Just a thought

[scitobor 617]

Do you think the accelerometer in last years kit could work? I don't think my school has an accelerometer for lab use, I'll check tomorrow.

[BrianBSL]

Originally Posted by scitobor 617

Do you think the accelerometer in last years kit could work? I don't think my school has an accelerometer for lab use, I'll check tomorrow.

Not for measuring 300G - IIRC its a 1.5G (in each direction) accelerometer.

[Bill_Hancoc]

Flash sounds like the way to go especially hearing about the compact flash and 40 pin connecter. i know this goes against what i just said but it may help. hitachi makes a hard drive CF card (if you think about this for a second and think about the "compact flash part it doesnt really make sense since its a hard drive) it has a really high shock protection and may be eaiser to shield from vibrations. cons are its kinda pricey----if it works you could start a lawn mowing business and profit on it.

Simple fix for this. Take a piece of insulation foam (go for half inch thick), and mount the hard drive bottom to it. Then, take the same foam and cut blocks about 1 inch square out of the same type of foam, mounting them to the bottom of the foam on the hard drive. Another full sheet on the bottom of the hard disk and it'll be good to go, just attach the very bottom piece somewhere on the comp case.

I'm pretty sure this'll work, but not 100%. The vibrations of a lawn mower on the ground may be a little more than a motor boat engine a friend of mine modified. The foam should dampen most of the shock to the HD, but you might want to increase the thickness of the blocks, to give it more room to move.

[scitobor 617]

Like this?

Sounds like a good solution but I'll probably need to do something about heat dissapation.

[Greg Needel]

Originally Posted by scitobor 617

I'll probably need to do something about heat dissapation.

bingo. hard drives will produce a fair amount of heat when running for long periods of time and you need to think about airflow around the drive for heat dissipation. If you are going to do something like this, I would consider getting a hard drive enclosure and foam mount the enclosure instead of the drive itself.


you also need to figure out if the foam will work, remember 1 hit to the platters and the drive might be dead.

Yah, that would work. The main thing is that whatever the HD is attached to is insulated from shock. A fan or two mounted on the HD mount would help the temp, and take care of it. The foam would make it so that HD is sheilded from vibrations.

[Andy A.]

I'm curious, how were you going to power it?

While hard drives are the most obvious targets of vibration damage, theres more to be worried about.

While most of the PC is solid state, none of it is 'shock/vibration proof'. Everything from the power supply down to the screws holding the motherboard to the case could be damaged from prolonged vibration. R/C plane builders know all about just how damaging vibration can be to even simple solid state electronics, and will wrap receivers in latex foam and servos are often shock mounted. High vibrations can crack solder joints, work heavy capacitors loose, loosen heat sinks, knock a RAM module out etc.

My guess is that even if you don't see a hard drive failure, you will see one somewhere else. I'm sure its possible to do this, and I think it has been. However, the desktop PC wasn't made to move around. And being bolted to a lawn mower is about as terrible environment as I can think of.

My suggestion is to look into buying an old laptop, perhaps a Toughbook. A laptop has been designed to move around and deal with a life of being dropped. You'll still have to do something about vibration, but at least you don't have to worry as much about powering it.

And be careful about advertised 'shock' and 'g loads'. Usually these numbers refer to a devices ability to handle drops when off. A spinning hard drive is much more apt to be damaged then one that is powered down.

-Andy A.

[Price Vetter]

The thing with flash memory is that it is much more expensive than a hard drive. Recently, I saw a DARPA car that had mounted the computers on tensioned wires, which, in turn, absorbed the shock produced by the terrian and the car.

[TechnocratiK]

Being an OS programmer, my instinct would be a flash chip on a motherboard that supports booting USB devices: if you're willing to pick up an assembly book, you can write your lawnmower control program in a matter of kilobytes. If, on the otherhand, you prefer something like Linux or Windows, why not just make the lawnmower tow the computer (on wheels) behind it?

[Wetzel]

Originally Posted by TechnocratiK

why not just make the lawnmower tow the computer (on wheels) behind it?

There is the "Why didn't I think of that" idea!

Wetzel

[scitobor 617]

Originally Posted by TechnocratiK

Being an OS programmer, my instinct would be a flash chip on a motherboard that supports booting USB devices: if you're willing to pick up an assembly book, you can write your lawnmower control program in a matter of kilobytes. If, on the otherhand, you prefer something like Linux or Windows, why not just make the lawnmower tow the computer (on wheels) behind it?

Hmm, I do have a cart that can be attached to my lawn mower, plus I have been running into some space issues.

[scottmso]

Yes, maybe you might want to make a laptop HD a consideration, those are supposed to be less sensitive to vibration than desktop HD's...