2011/7/26 Andrew <[email protected]>:
> 2011/7/26 Dave <[email protected]>:
>>
>> My question is:  What would be the best way to implement this two "X"
>> axis control scheme with EMC2?
>
> I'd suggest a custom kinematics file, probably based on gantrykins.
> With HAL pin connected to hardware switch choosing between tables.
>

I see 3 theoretical solutions:
1) You have a g-code filter, which substitutes X with U for the parts
to be produced on second table

2) You can write custom HAL component with 4 inputs and 4 outputs and
1 selector pin, so that You can take these pins:
axis.m-pos-cmd
axis.m-pos-fb

axis.n-pos-cmd
axis.n-pos-fb

and link them to these pins:

motor.m-pos-cmd
motor.m-pos-fb

motor.n-pos-cmd
motor.n-pos-fb

in a following way:
If selector is "false", then

axis.m-pos-cmd <-> motor.m-pos-cmd
axis.m-pos-fb <-> motor.m-pos-fb

axis.n-pos-cmd <-> motor.n-pos-cmd
axis.n-pos-fb <-> motor.n-pos-fb

If selector is "true", then

axis.m-pos-cmd <-> motor.n-pos-cmd
axis.m-pos-fb <-> motor.n-pos-fb

axis.n-pos-cmd <-> motor.m-pos-cmd
axis.n-pos-fb <-> motor.m-pos-fb

Obviously, You can switch them _only_, when corresponding pins of m
and n are equal. That is, X and U positions have to be the same.

3) My favorite option would be the one already suggested by Andrew -
custom kinematics module.
I was thinking that also this solution would require putting both
tables in equal positions, but then I realised that this is the place,
where it can be hacked. I just did not yet come up with a solution.
I just would like to oppose Andrew's opinion about using gantrykins as
the place to start - I do not think so, because gantrykins is
generalised for any kind of "2 joints on a single axis" combinations
and thus it actually is pretty complicated.
I think that You should start simply with trivkins and do 2 things:
a) add a HAL pin
b) in forward and inverse kins add the "if the HAL pin is true or
false" conditions and how tran->pos.x and pos->u are related to
joint[m] and joint[n]


I think that both last options are of equal level of difficulty, IMHO
not very hard.
In any of the cases You can drive the selector pin with M64 command
from g-code so that operator just needs to change the parts, but
machine does all the production in non-stop.

Viesturs

------------------------------------------------------------------------------
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Research study explores the data loss prevention market. Includes in-depth
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http://www.accelacomm.com/jaw/sfnl/114/51385063/
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