Re: tool changer logic- mathematical challenge

This is an existing design from an Emco Turn 120 cnc lathe that I'm
retrofitting/reverse engineering (I've never seen the machine
operate, it was purchased with bad controls). The tool turret
assembly is a very small, integrated package. Any sensor changes
will require modification. I'm not ruling out other options,
however, operating the turret as is would be the most preferred at
this point.

Due to the ratcheting mechanism, the turret will have to move
slightly past and then revese back into postion after the sensor is
tripped (sensor trips a motor reversing relay). I believe field of
view of each sensor will allow this overshoot, which is necesary for
proper operation. However, it is all relative, and the problem can
be solved by assuming an infinitely small sensor field of view.

Let's see some answers.


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Bob McKnight"
<bobmcknight@c...> wrote:

>
> How many degrees of vision does each optical sensor cover.
>
>
>
>
> 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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