I thought I remembered a name for that from college physics.
Velocity is meters/sec
Acceleration is meters/sec^2
Jerk is meters/sec^3
Jerk is the rate of change of acceleration.
http://en.wikipedia.org/wiki/Jerk_(physics)
On Mon, Sep 19, 2011 at 3:02 PM, Andrew parallel.kinemat...@gmail.com
On 19 September 2011 21:02, Andrew parallel.kinemat...@gmail.com wrote:
Thinking about decreasing stepper (and servo, to some extent) torque at
higher speeds, I just thought that having variable axis acceleration would
be perfect. I.e., the highest at lower speeds and lower at higher speeds. Is
I would think that this would be very hard to implement successfully.
You are talking about optimizing the acceleration settings to a
particular motor/drive/load setup.
I can only see this being of a benefit if you were running a fixed part
with the same cutter over and over again with a
Although my education, long ago, was in physics, I do not really
understand the physics of electric motors.
Are there reasons to limit the rate of change of acceleration?
for example: Are there reasons that one would not want to go from max
acceleration in one direction to max acceleration is
2011/9/20 Dave e...@dc9.tzo.com
I would think that this would be very hard to implement successfully.
You are talking about optimizing the acceleration settings to a
particular motor/drive/load setup.
I can only see this being of a benefit if you were running a fixed part
with the same
On 20 September 2011 16:01, craig cr...@facework.com wrote:
Although my education, long ago, was in physics, I do not really
understand the physics of electric motors.
Are there reasons to limit the rate of change of acceleration?
Two different idea have been conflated here.
Andrew was
The rate of change of acceleration is Jerk.Limiting Jerk literally
make the machine less Jerky which is much more noticeable when running
at high speeds.
Andy hinted at it with car braking..Have you ever been in a car with
a new driver? Oftentimes everyone suffers from a bit of
On 9/20/2011 11:34 AM, Andrew wrote:
It looks like lack of capacity at
higher speed.
You may be simply running out of servo power.
Servos oftentimes have some reserve power that you can use for a short
period of time, but that is limited.
If your drive power supply is undersized, that
2011/9/20 Dave e...@dc9.tzo.com
On 9/20/2011 11:34 AM, Andrew wrote:
It looks like lack of capacity at
higher speed.
You may be simply running out of servo power
I've thought about it already, thanks. That's what I intend to try -
increase supply power.
Servos oftentimes have some
On Tue, 20 Sep 2011, Andrew wrote:
Date: Tue, 20 Sep 2011 19:38:08 +0300
From: Andrew parallel.kinemat...@gmail.com
Reply-To: Enhanced Machine Controller (EMC)
emc-users@lists.sourceforge.net
To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
Subject: Re: [Emc-users]
- Original Message -
From: Steve Stallings steve...@newsguy.com
Accomodating a variable acceleration limit would
seem to be fairly complex.
Perhaps there is a solution that would offer some
of the benefit without as much pain.
Since rapid moves are done without cutting loads,
On Tue, 2011-09-20 at 19:38 +0300, Andrew wrote:
... snip
It just stops and shows something like Overvoltage when connected to PC.
... snip
I've seen this message from my VFD's while setting up dynamic braking
where the motor back EMF from motor deceleration (motor becomes more
like a generator)
On Sep 20, 2011, at 11:09 , John Prentice wrote:
On a related topic I have wondered if it would be possible to have a second
set of following error settings for rapids. I feel in my tuning that I
sacrifice rapid performance to avoid errors that really only need to be
tight during cutting.
craig wrote:
Although my education, long ago, was in physics, I do not really
understand the physics of electric motors.
Are there reasons to limit the rate of change of acceleration?
for example: Are there reasons that one would not want to go from max
acceleration in one direction to
On Tue, 2011-09-20 at 18:09 +0100, John Prentice wrote:
... snip
On a related topic I have wondered if it would be possible to have a second
set of following error settings for rapids.
... snip
I think there is, in the .ini file:
FERROR = 0.001 -- Normal error
MIN_FERROR = 0.005 -- Low
On Tuesday, September 20, 2011 03:45:13 PM craig did opine:
Although my education, long ago, was in physics, I do not really
understand the physics of electric motors.
Are there reasons to limit the rate of change of acceleration?
Every hear of E=MV2? The machine has a mass that must
Gene, just for the records: kinetic energy E = 1/2 times M times V
square. We are not on relativistic terms here. But as far as this
current discussion is concerned, this is not so important.
Peter
gene heskett schrieb:
On Tuesday, September 20, 2011 03:45:13 PM craig did opine:
I have a Hitachi SJ200 VFD that I will be hooking up to EMC. I'm just
wondering what the best combination of signals I should use to control, and
monitor it.
What it seems to lack, compared to my servo amplifiers, is an Enable line,
something that stops it from doing anything unless the Enable
On Mon, 19 Sep 2011 23:02:08 +0300, you wrote:
Thinking about decreasing stepper (and servo, to some extent) torque at
higher speeds, I just thought that having variable axis acceleration would
be perfect. I.e., the highest at lower speeds and lower at higher speeds. Is
that ever possible with
On Tuesday, September 20, 2011 06:10:14 PM Peter Blodow did opine:
Gene, just for the records: kinetic energy E = 1/2 times M times V
square. We are not on relativistic terms here. But as far as this
current discussion is concerned, this is not so important.
Peter
And I have never seen
On 20 September 2011 22:29, Frank Tkalcevic fr...@franksworkshop.com.au wrote:
What it seems to lack, compared to my servo amplifiers, is an Enable line,
something that stops it from doing anything unless the Enable is asserted.
Generally if neither Forward nor Reverse are set, nothing
On Wed, 2011-09-21 at 07:29 +1000, Frank Tkalcevic wrote:
I have a Hitachi SJ200 VFD that I will be hooking up to EMC. I'm just
wondering what the best combination of signals I should use to control, and
monitor it.
I'm using two digital pins and a DAC to run my SJ200. So far, so good.
Adding
John Prentice wrote:
On a related topic I have wondered if it would be possible to have a second
set of following error settings for rapids. I feel in my tuning that I
sacrifice rapid performance to avoid errors that really only need to be
tight during cutting.
EMC2 already has it!
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