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Padu posted on August 17, 2005, 6:42 pm
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
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
Mr Clarke posted on
Re: Electronics Shock Absorption
the magnetic back-EMF damped more with increased velocity.
Put coils around them and they could keep your batteries topped-up too.
-----------------------------------------------------------------------
Ashley Clarke
-------------------------------------------------------
NMail posted on
Re: Electronics Shock Absorption
"Mr Clarke"
JGCASEY posted on
Re: Electronics Shock Absorption
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
Eljin posted on
Re: Electronics Shock Absorption
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:
Matthias Melcher posted on
Re: Electronics Shock Absorption
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:
J. Clarke posted on
Re: Electronics Shock Absorption
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.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)
Tim Auton posted on
Re: Electronics Shock Absorption
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
--
You are being watched. This gives you power.
Brian Dean posted on
Re: Electronics Shock Absorption
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
--
Brian Dean
ATmega128 based MAVRIC controllers
http://www.bdmicro.com/
Chris Spencer posted on
Re: Electronics Shock Absorption
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
joecoin posted on
Re: Electronics Shock Absorption
Maybe something like this?
http://www.smallparts.com/products/descriptions/asd.cfm
Joe
Naveed posted on
Re: Electronics Shock Absorption
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
Wonko posted on
Re: Electronics Shock Absorption
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.
Ivar Ylvisaker posted on
Re: Electronics Shock Absorption
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
John Nagle posted on
Re: Electronics Shock Absorption
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
Wayne Lundberg posted on
Re: Electronics Shock Absorption
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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