Re: [CAD_CAM_EDM_DRO] Re: tool changer logic- mathematical challenge

You should not need active on and active off inputs.
All you will need to do is see when any input goes on
or off.
--- Lance Hopper <snaggletto@...> 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.
>
>
>
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