Electronics Shock Absorption

Hey all
I had this crazy idea, and as usually happens when you have a crazy idea (that you think you have just invented), someone already did it. So, I'd
appreciate a few pointers.
Let's say you're designing a wheeled robotic platform a little smaller than a golf cart that is intended to run on rough terrain and you want to isolate the electronic components from shocks. The platform already has shock absorbers on each wheel, but I feel that won't be enough.
My idea is to hang the "electronics box" with strong elastic cords, one cord in each corner of the box (8 in total) in a way that all cords are tense enough not to allow the box to crash into the chassis but relaxed enough to allow some dumping of the shock.
Do you think it could work?
Think of it as a box fluctuating (with the help of the bungees) inside a tubular frame.
Padu
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Even crazier would be to use small strong magnets inside tubes so that the magnetic back-EMF damped more with increased velocity. Put coils around them and they could keep your batteries topped-up too. ----------------------------------------------------------------------- Ashley Clarke -------------------------------------------------------

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that is a neat idea.
Mr Clarke wrote:

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Wow, a maglev suspension system! Did anybody tried that already?
"Mr Clarke"

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Padu wrote:

It reminds me of how you can use an electric magnet to hold a metal ball in suspension just below it using feedback via a light beam.
electric magnet <------| | light ----> ball -----> light sensor
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Yes the Japanese call it a bullet train. It's a beautiful idea that goes some ungodly speed on land. Unfortunately that idea would mess around with the electronics...
I think he was asking a serious question.
Padu wrote:

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And we Germans call it Transrapid. They are faster than airplanes and stand on 10m high ugly concrete bridges - maybe - if they will get built.
http://transrapid.de/en/index.html
Eljin wrote:

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Eljin wrote:

I hate to jump in so late in a thread, but this is a common misconception. The Japanese are experimenting with maglev but the bullet trains run on conventional rails with conventional wheels.

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--John
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[snip]

That would deal with individual shocks reasonably, but without any damping it might just go completely wild at resonant frequencies. You can be sure you'll find those resonant frequencies often enough driving over rough terrain. I can't think of a simple way to add damping, but gas struts from car hatchbacks or the like may provide an inexpensive source.
I expect you'd need something pretty elaborate mechanically to beat a couple of inches of the right sort of foam.
Tim
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On Thu, Aug 18, 2005 at 03:44:45AM +0100, Tim Auton wrote:

Reminds me of the story during the space race about NASA spending millions trying to design a pen that writes in zero g. The Russians just used a pencil :-)
-Brian
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Brian Dean wrote:

Indeed. Although that's an amusing, but false, urban legend.
http://www.snopes.com/business/genius/spacepen.asp
"Fisher Space Pens are more dependable than lead pencils and cannot create the hazard of a broken piece of lead floating through the gravity-less atmosphere."
Chris
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Maybe something like this?
http://www.smallparts.com/products/descriptions/asd.cfm
Joe
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"joecoin"

Humnn, good suggestion, thanks!
Padu
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than
isolate
cord
to
If you had wires attached to the circuit board and the circuit board vibrated then possible damage to the wires might occur or the joints might break between wire and circuit board. Concentrate on the suspension of each individual wheel or design the hardware to be more robust.
Naveed
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Don't work too hard to solve the problem until you're sure you need to.
The real point is not to isolate the electronics from shock, but to prevent damage from shock. I'd start out by gluing any components you're concerned about to the circuit board, like capacitors and other large components that might wiggle or break loose. Fasten your connecting wires to the board so there's no strain on the connection. If you'll need to connect and disconnect a lot try a Velcro cable tie with a corresponding Velcro strip on the board. Use rubber gaskets as washers on *both* sides of your circuit board mounting bolts. As someone already suggested, some soft foam ( the kind from the box your hard drives came in ) can be useful too.
Good luck! It sounds like a fun project.
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Wonko wrote:

With the proper mechanical design, fairly ordinary electronic equipment can survive horrific shocks. Years ago, I was working on a project that among other things developed sensors that were fired out of army artillery. G forces were on the order of 30,000 g's if I remember correctly. It was important to mount components so that they rested on the circuit board and did not slap against the board when the gun was fired. Also, the electronics were immersed in a potting compound to help distribute and absorb the shock. I have forgotten what kind. Of course, we knew which direction the shock was coming from.
While electronics can be made very rugged, one can destroy a lot of equipment while learning what not to do.
Ivar
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Padu wrote:

That approach tends to take up too much space, and it's mostly spring without enough damping.
Shock mounts for electronics boxes are standard commercial parts. See
http://www.sdp-si.com/eStore/CoverPg/Vibration.htm
                    John Nagle
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Many interesting replies. I'd go up to Otay Mesa's auto junk yards and study how the many fuse boxes, computers and other electronics are mounted in any all terrain vehicle or Jeep. I agree with the poster who suggested making the electronics circuit board and housing robust with minimum additional 'junk' that would simply add bulk and weight.
Wayne
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That is how my washing machine tub us mounted, except that it uses steel springs - works well
David
Padu wrote:

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