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Old December 20th, 2017, 06:14 AM   #1

aand74 is offline
Join Date: Dec 2005
Location: Deinze
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Calculate cam

In my motion program an axis is cammed to a master axis.
The first cam is for axelerating the slave axis, a 5th order polynome is used.
After that a linear cam takes over that makes the position difference between master and slave constant over its range.
The cams are calculated in the program, a function block from the drive manufacturer is used for that. For the acceleration cam I can parametrize a start speed (here 0), end speed (here 1 = same as master), start acceleration (here 0), end acceleration (here 0), start and end point of the master, start and end point of the slave (the positions are absolute).
This all works.
But I should want the acceleration phase to be done with a known maximum acceleration. For that the master range over which the acceleration is done can be variable (will be suited for the requested maximum acceleration).
Does somenone know how I could influence the cam calculation to obtain a cam that accelerates with a known maximum acceleration?
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Old December 20th, 2017, 11:43 AM   #2
James Mcquade
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Please give us the plc you are using, the motion module, software.
cad cam software.

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Old December 20th, 2017, 02:58 PM   #3
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jstolaruk is offline
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Location: Detroit, SouthEast Michigan
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If its Rockwell's RSL5K motion instructions, get familiar with the MCCP instruction. You can directly manipulate the input cam array which creates the cam profile for use with MAPC. Works well, I've modified by hand or thru logic.
"You can live to be a hundred if you give up all the things that make you want to live to be a hundred." Woody Allen
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Old December 21st, 2017, 03:07 AM   #4

aand74 is offline
Join Date: Dec 2005
Location: Deinze
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The system is Simotion D425-2 FW4.4.
Now I use a function from their 'Easy Basic' library.
With that I can create cams in runtime with parameters like startposition, starvelocity, startacceleration, endposition, endvelocity, endacceleration for polynomial 5 functions.
This works ok, but I want to have control on maximum velocity and maximum acceleration of the cam. For that I allow to make the definition range of the cam variable.
Has someone experience with creating a cam with these parameters.
I should need a function that creates the polynomial coefficients for the cam.
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Old December 21st, 2017, 02:32 PM   #5
Peter Nachtwey
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Won't Siemens tech support help you with this?
Why do you need a fifth order polynomial at the start?
Is it because you want the both start velocity and acceleration to be zero at the start.
If the distance between the master and slave is constant to you really want to use a cam table?
What is the application. It appears you want to ramp up the slave to be synchronized with the master velocity for a flying cut off or similar application. If so then once the axes are synchronized don't you want to gear instead of cam?
"Living is easy with eyes closed, misunderstanding all you see...." Strawberry Fields Forever, John Lennon
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Old December 21st, 2017, 02:46 PM   #6

aand74 is offline
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Location: Deinze
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For the moment this is not a concrete application, but it is to have a principle working, that then later could be used in applications.
I know gearing is an alternative (for some first choice).
But I wanted to know if someone ever did something as I described, it does not matter what brand is used.
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Old December 21st, 2017, 06:50 PM   #7

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