Slip Sheet Sensing 2

[Farmboy71]

I am working on a project where I need to pick a fiber(or corrugated) paper slip sheet with a robot. Does anyone know of a sensor that would detect if multiple sheets were picked? It would be best if it would be non-contact and only need to see the sheet from one side. Any ideas? Thanks in advance.

 

[MacGyverS2000]

I would put some weight behind Farmboy's vacuum theory. Ever broken a board using a single sheet of newspaper as a child? Lay a piece of wood, like a 1x1 over a counter's edge. With a full 2-section sheet of newspaper, spread it over the counter so it also covers the end of the wood stick, then smooth it out as much as possible. Take a second stick and give the first a good whack... if set up properly, the first should break near the counter's edge. Nothing holds the first stick down except the vacuum created under the newspaper... you're trying to lift the paper up so fast when you hit the stick, the air cannot enter quickly enough around the edges, so it acts like a pretty darn good vise.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[itsmoked]

Hey Dan thanks for explaining that. I have actually seen that setup somewhere before but never slowed down enough to wonder what it was for.. Now I know.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[machmech]

Hello Dan

Good point! Although this is nothing more then a card
trick there are many other forces at work there. This
example is a little out in left field, but lets use it!
Now imagin just before the 1x1 is hit, three columns
of 22 P.S.I of compressed air is inserted between counter
and newspaper. How much vacuum will be there at the
time the 1x1 is struck? air is still on, now how much
after it is struck.

Heck if you try to lift machined plate steel one straight up
from the other they will stick together, due to vacuum.
The process needs help.

Our process does not allow vacuum. Does this make sense or
have I been in the think tank too long?

Chuck

A government which robs Peter to pay Paul
can always depend on the support of Paul.
- George Bernard Shaw

 

[lighterup]

Farmboy,
Back to your original question of the sensor; ultrasonics provide a reflection of the transmitted signal at each material boundary. If you aim the sensor perpendicular to your paper surface, you will see a strong reflection from the top surface of the slip and a weaker reflection from the bottom surface, separated in time. You will see progressively weaker reflections from subsequent layers of slip which may be stuck to the top slip.
Although these sensors are primarily designed to measure liquid levels and things like that, you might be able to get with the applications guys from a company like the one below to see if they can talk you through how to macgyver their sensors to work for you.

http://www.sensorsforindustry.com/prod13.htm