force measurement

Archiver

I need to measure the impact force of martial arts strikes. My first
choice would be the use of a load cell but those puppies are quite
expensive. The expected force is between 500 and 5000psi. Accuracy
of plus or minus 10% is very acceptable. I need to keep the cost as
low as possible (ever heard that before? [noparse]:)[/noparse] ).

Any ideas would be appreciated.

Archiver

here is one thought.
maybe a pressurized chamber made out of rubber or???? with some sort of
pressure sensor.
when the strike occurs the internal pressure should rise and then some how
use the sensor to measure internal pressure.
this is just a start.

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Original Message

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From: "venslein" <enslein@h...>
To: <basicstamps@yahoogroups.com>
Sent: Saturday, January 12, 2002 4:39 PM
Subject: [noparse][[/noparse]basicstamps] force measurement


> I need to measure the impact force of martial arts strikes. My first
> choice would be the use of a load cell but those puppies are quite
> expensive. The expected force is between 500 and 5000psi. Accuracy
> of plus or minus 10% is very acceptable. I need to keep the cost as
> low as possible (ever heard that before? [noparse]:)[/noparse] ).
>
> Any ideas would be appreciated.
>
>
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Archiver

I know some one who made drum pads using a disc of Plexiglas with a
piezo disc glued to the bottom surface the output was routed to an A/D
he was able to force from this very easily. But the voltage can easily
exceed the safe input the the A/D so you would need to protect the input
and they are very sensitive If you take a disc and mount it by one edge
so it stands vertically and put a simple bar coming off the top side
going horizontal you can easily detect someone walking on a concrete
floor.

======================== horizontal pendulum
|
| piezo disc
|
======= bottom mount

You may be able to set the bottom threshold by careful selection of the
striking surface so you get little to no output until the force exceeds
the lower limit

Craig


> Subject: force measurement
>
> I need to measure the impact force of martial arts strikes. My first
> choice would be the use of a load cell but those puppies are quite
> expensive. The expected force is between 500 and 5000psi. Accuracy
> of plus or minus 10% is very acceptable. I need to keep the cost as
> low as possible (ever heard that before? [noparse]:)[/noparse] ).
>
> Any ideas would be appreciated.