Detecting and locating footsteps economically

[kmlee]

Hi to all

I have an application where I wish to detect both the footsteps of a
person *and* the location. I�m using a piezoelectric cable since it can
measure activity some distance away, due to its microphonic properties.
Then, when someone steps on the cable, it will close a contact of some
kind. There will several contacts laid out at say, 0.5 meter intervals.
In order to locate a footstep, the contacts should not close too
readily. I enclose the schematic of one contact along the cable.

/ / <==cable
__/ /__
/ O/ / <==contact
/______/

It is the contact that is a bit of a concern.

I was thinking of using the following:

1) Tactile switch. I have seen parts that are 0.47-0.55 mm thick. But
when someone steps on the switch, it may be damaged in due time, as
these switches are rated at 1.6N or so when activated.

2) Membrane switches. Seems to be able to lie flat and are capable of
high pressure.

I would appreciate any comments from users who have designed similar
systems.

Thank you in advance.

[Marte Schwarz]

Hi,

> I have an application where I wish to detect both the footsteps of a
> person *and* the location.

That is exactly that what I have to develop actually. You can send me more
details what you need. May be my system will fullfill your needs or I may
offer you a solution to built

> I�m using a piezoelectric cable since it can measure activity some

> distance away, due to its microphonic properties. Then, when someone steps
> on the cable, it will close a contact of some kind. There will several
> contacts laid out at say, 0.5 meter intervals.

.5 meters seems to be too much, this is more than one footlength so the foot
may stand between the cables.

> I would appreciate any comments from users who have designed similar
> systems.

I invite you to write your needs in detail

Regards

Marte

[boB]

Marte Schwarz wrote:
> Hi,
>
>> I have an application where I wish to detect both the footsteps of a
>> person *and* the location.
>
> That is exactly that what I have to develop actually. You can send me more
> details what you need. May be my system will fullfill your needs or I may
> offer you a solution to built
>

>> I�m using a piezoelectric cable since it can measure activity some

>> distance away, due to its microphonic properties. Then, when someone steps
>> on the cable, it will close a contact of some kind. There will several
>> contacts laid out at say, 0.5 meter intervals.
>
> .5 meters seems to be too much, this is more than one footlength so the foot
> may stand between the cables.
>
>> I would appreciate any comments from users who have designed similar
>> systems.
>
> I invite you to write your needs in detail
>
> Regards
>
> Marte
>
>

This reminds me of the show, "River Dance" (among others) where the
had the fantastic capture of the heel/foot dancing sounds. I never
did figure out HOW they did that recording. Directional microphones
on the stage ??? Foot triggers on their legs ???

Michael Flarety or something like that.

boB

[mi...@sushi.com]

On Nov 23, 7:07 am, kmlee <km...@email.dot.com> wrote:
> Hi to all
>
> I have an application where I wish to detect both the footsteps of a

> person *and* the location. I’m using a piezoelectric cable since it can

> measure activity some distance away, due to its microphonic properties.
> Then, when someone steps on the cable, it will close a contact of some
> kind. There will several contacts laid out at say, 0.5 meter intervals.
> In order to locate a footstep, the contacts should not close too
> readily. I enclose the schematic of one contact along the cable.
>
>          / / <==cable
>       __/ /__
>      /  O/  / <==contact
>     /______/
>
> It is the contact that is a bit of a concern.
>
> I was thinking of using the following:
>
> 1) Tactile switch. I have seen parts that are 0.47-0.55 mm thick. But
> when someone steps on the switch, it may be damaged in due time, as
> these switches are rated at 1.6N or so when activated.
>
> 2) Membrane switches. Seems to be able to lie flat and are capable of
> high pressure.
>
> I would appreciate any comments from users who have designed similar
> systems.
>
> Thank you in advance.

This is already done using TDR techniques. It's been a commercial
product for about 15 years. They use fiber optic cable.

http://www.fiberopticsplus.com/images/brochure.pdf
One of many companies. I guess this is so old the patent has expired.

The piezo cable isn't all that bad of an idea for detecting an
intruder, but I'm not sure how easy it is to get position information
from a piezo cable.