Questions about designing a safety mat

Pardon me, but it sure sounds like a homework problem. What have power
supplies to do with mats? What is your interest in such a system?
Seems counter-intuitive that a safety region should be partially
compromiseable. The safety region is exactly for one and only one
purpose, to make the person safe by being sure it is not in the robots
area, or that the robot stops when one is. To be reduced so a person
could get closer to an unsafe area seems a horrible idea. Unless you
have further justification, I don't get it.

--
Randy M. Dumse
www.newmicros.com
Caution: Objects in mirror are more confused than they appear.

It is not a homework problem, this is part of a bigger project I'm
working on. The idea is to retain the robot to be safe but also save
some work area. This safety mat is mainly used as a pressure mat the
same idea as a touch screen, just to basically find the distance
between an obstacle and the robot (like the distance sensor). Instead
of using IR sensor/capacitor sensor on the ceiling or any other type
of sensor, the idea is to use the mat to find which area of the grid
the obstacle is located. Depending on the location, there are
appropriate messages sent to the robot. I guess I should've called it
pressure mats.

the robot would

it has been done by Mr Pilz with a camera

http://www.pilz.com.au/safetyeye.htm

you could use a mat, but mats are usually a homogenous thing...you would
need several zones instead...easy enough to do I guess with strips of
matting wired up

instead of USB, wire it to the printer port and use a BASIC or VB
program to read the inputs and creat some actions

to do it with a camera...webcam and directshow filters, unless you don't
have the height for viewing angle!

then do it with a ring of cameras looking in

Maybe I am just being Obtuse(like that is odd for me ;) ) but since
you know about touch screens then you know that Palm/Handheld devices
used a grid to pickup stylus position, just do the same thing but on a
bigger scale withthe needed Grid points or resolution.

Place sheet of the size of the mat with one side of the contact points
face up. Place another with holes in it where the contact should be.
Place the thrid sheet withthe contact points on it face down, align
all three. Place protect rubber over the top. Connect to Circuit...

Ever take a keyboard apart? Take a look. Chances are 50/50 it will be
the kind you are looking for and just do that bigger. I have made such
"mats" pads in the past and used the plastic sheets from the local
hobby store and a punch for a tarp eyelet to create the "holes"
contact points. the contacts and traces were drawn on by a trace
repair pen and a straight edge.


The Hirudinea

wrote:

As a side note, "Safety" mats are usually not monitored by the system
they are protecting. Computers fail (bad software, poor sensing etc.).
When it comes to a true safety mat things get a bit more basic or at
least multiple redundent.Safety requires a more direct approach such
as a removal of power when safety is breached. Nothing like a high
speed/high energy system that does not stop because of a software
glitch. Light curtains are used but are usually not as part of the
system they are monitoring, they are seperate and closed systems that
have been qualified before they can be used as safety devices. Safety
doors use switches that again interupt power, not send a signal to the
system to stop an action. The signal may still be sent but it is not
the primary "stopping" source.

Using a grid system would be ok to a point, but the final boundry
( before human interaction with the danger source) must fall into the
more direct approach.

We come compacent working with computers these days as computers
control more and more but software is never perfect. Safety must be.

Thanks everyone for the help. Appreciate all the information