John
We used to measure the acceleration rather than calculate it.
We loaded the axis with whatever tooling and 'normal' work piece,
then, in open loop,
we applied a voltage that would achieve the max velocity, very briefly.
just a bit longer than necc to get to the max velocity ( some hundred of
millisecond, not whole seconds )
then we measured how long it took to get to the max velocity
_that_ is your practical acceleration in one direction
the test is called a ';step' response
it has nothing to do with stepper motors
it has to do with the immediate 0 to max velocity command
that's the 'step'
on a dual trace storage scope you should monitor the velocity command
and the velocity.
hth
tomp
( this acc will be greater than the whole machine can achieve turning
sharp corners and reversing
but its a real, practical start value )
On 7/23/20 12:57 PM, John Dammeyer wrote:
Hi Chris,
-----Original Message-----
From: Chris Albertson [mailto:[email protected]]
Why on Earth do people still use US units? OK if your final result must
be expressed that way, but do the math in metric then convert at the end.
<SNIP>
I taught high school science for a while and never once would ever talk
about US units like feet or pints or pounds. The students had no problems
with this as their middle school teachers did the same. No one who is
educated in the last few decades would know how to work with "feet per
second squared"
Appreciate the comments. But even if I used the servo motor 1.6Nm the pitch of the
lead screw is 0.2" so I could easily convert that to 5.08mm or 0.00508m for
that matter. In Canada much of what we do is metric. And my program has a check
box that lets a user switch along with converting all the imperial units to metric
and back.
But that's beside the point I think. None of what you said explains how to
calculate the MAX_ACCELERATION in the INI file given parameters like
motor/leadscrew torque, leadscrew pitch, max speed and table weight (mass).
Any ideas?
John
Chris Albertson
Redondo Beach, California
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