I sure ultrasound would work,
the problem may be to do with the beam divergence. The ultrasound will
reflect
off most surfaces in the sensors field of view, ie
the shower rail, windowsill, the bath rim, water or bottom of bath.
I’m
not sure with the ultrasonic tape measures what the beam angle is like, I
don’t
have one. If it could be made very narrow there should be no
problems.
Alternatively, given that the ranges
of interest
are known, you maybe able to filter the unwated
refelections out by selectively
sampling
the reflected sound wave at the desired time. You should be able to get an
accuracy
of about .5cm over the range of bath empty to bath
full.
A colleague of mine developed a cheap
sonar
sensor that gave rs232 out and measured the distance to the first 8
objects. This
may work as it is likely that the water could be made to be the second
object,
given that the first would probably be the bath
rim.
Just a few
thoughts…
Iain
-----Original Message-----
From: PatrickLidstone
[mailto:patrickl@xxxxxxx]
Sent: 12 August 2002 13:45
To: ukha_d@xxxxxxx
Subject: [ukha_d] Re:
Measuring
bath water depth
--- In ukha_d@y...,
Stuart
Grimshaw <stuart@s...> wrote:
> On Monday 12 Aug 2002 1:20 pm, Stuart
Poulton
wrote:
> > Patrick,
> >
> > I like the idea of this, be
interesting to see if anyone is able
to try
> > this.
> >
> > There are of course ustrasound
sensors
used in robotics available.
>
> What about using a capacitence probe? Two
strips of metal, the more
water in
> the tub, the greate/lesser the
capacitence.
Have a look at
epanorama.net for
> more info.
I was interested in ultrasound because it is
non-intrusive. Probes in
the bath are unsightly, are difficult to
secure
mechanically, have a
poor SWMBO factor, and, perhaps most
importantly,
would, I think, be
unreliable - since most probes rely on the
wet-dry
factor, resulting
in false readings in any situation in which
the
probe starts off from
anything other than bone
dry...
Patrick
For more information: http://www.automatedhome.co.uk
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