Re: tool changer logic- mathematical challenge

Now you're cheating :), your changing the problem, earlier you
said "each" and relating to state change. I had the 135 (45 tool
offset plus 90 sensor offset), but now you mention 2 sensors at a
time. Technically, to solve the word problem part, you can also 225
degree opening.

Word problems suck. Give me a digital camera any day.


As far as making it work… Think PIC

For a $50 setup you can make is do a little dance and sing a little
tune whenever you request a tool change and still get the position.

Seriously, a PIC is a cheap good little solution that you might want
to look into. The PIC itself is just a few bucks, the PIC burner is
the rest.


Thanks
Aaron Moss
www.IndustrialHobbies.com





--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lance Hopper"
<snaggletto@c...> wrote:

> Hello,
> You seem to be on the right track, but not there yet. You have

to

> think of it as this;
>
> What angle of opening, will create 2 trip points, so that sensors

at

> 90 deg. to eachother will trip every 45 degrees?
>
> Imagine an arrangement of 4 sensors at 90 deg. "+" represented by

a

> crosshair. Now imagine a "C" shape. Put the + into the C and

align

> one point of the + with one of the endpoints of the C. This
> represents a trip location.
>
> Now forget about the currently tripped sensor, look at the next
> one, which is currently out in the opening of the C. We want this
> one to trip in another 45 deg of movement. So, 90 (between

adjacent

> sensors) and another 45 deg. of movement for the not-tripped sensor
> give 135 degrees.
>
> If you lay it out in CAD you will see that every 45 degree
> rotation causes one of the 4 sensors to trip on one side of the 135
> deg C opening every time. However, this means that I will have to
> check each sensor for when the go from 0 to 1 and for when each

goes

> from 1 to 0. In other words, it appears I will need 4 active LO

and

> 4 active HI inputs to read the position of the turret. Also, one
> output for a DPDT forward/reverse relay.
>
> I'm not so sure Mach2 with 2 parports will do this. I'm kinda
> thinking about a small $99 PLC with 8 inputs and 6 outputs to do

the

> tool turret. Mach2 will just send a 'start' signal to tell the PLC
> to run it's program, then maybe recieve a 'done' signal from the

PLC

> after the tool change is complete etc... Got some thinking to do

on

> this.
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "industrialhobbies"
> <admin@i...> wrote:
> > This is just a WAG (wild ass guess).
> >
> > To do it with only one sensor active (or not) at a time 45 degree
> > opening 22.5 degrees out of angular alignment with the number 1
> > position.
> >
> > That would meet the requirement of a single sensor (of four), and
> in
> > this case any opening between 22.5 and 45 degrees would work.
> >
> > Somewhere else you mentioned a backup circuit, backing up to hold
> > position, you would need to change the angular alignment from

22.5

> > degrees out, to 0 degrees (just enough to trip the sensor). That
> > would allow you to index all the way around through each of the 4
> > sensors and change the state of one sensor at a time, based on

only

> > 45 degrees of motion.
> >
> > The offset of angular alignment is only needed for real world
> > applications, theoretically it's not needed.
> >
> > Thanks
> > Aaron Moss
> > www.IndustrialHobbies.com
> >
> >
> >
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lance Hopper"
> > <snaggletto@c...> wrote:
> > > Test yourself, see how good you really are...
> > >
> > > Given; a ratcheting action, rotary tool turret with 8 positions
> (a
> > > tool every 45 degrees). The turret can only index going one
> > direction.
> > >
> > > Given; a series of 4 optical sensors, spaced evenly @ 90

degrees

> > > around a circle.
> > >
> > > Given; a "C" shaped, semi-circular raised area that passes thru
> and
> > > blocks/unblocks the optical sensors as it rotates with the tool
> > > turret. This creates 2 state change areas for each of the 4
> > > sensors. Assuming the "C" shape, and CCW motion, you can see
> that
> > > each of the 4 sensors will go from blocked to unblocked, and
> > > unblocked to blocked as the turret rotates.
> > >
> > > Problem; how many degrees is the opening of the semi-

circular "C"

> > > shape that will create an off - on and on - off transition for
> each
> > > of the 4 sensors. Resulting in an index resolution of 45

degrees

> > > when only looking at one sensor at a time.
> > >
> > >
> > > This is easier than it first appears, however, I never could
> figure
> > > it out without help. I thought this might be an interesting
> > > challenge for others. See what you come up with. Good luck.