On Sunday 29 August 2021 14:54:12 Rob C wrote:
> any interest / help
>
> https://www.pmdcorp.com/resources/type/articles/get/mathematics-of-mot
>ion-control-profiles-article
>
Figure 4 of that link largely describes linuxcnc current reversal profile
if a second inverted waveform is assumed at a
any interest / help
https://www.pmdcorp.com/resources/type/articles/get/mathematics-of-motion-control-profiles-article
On Sun, 29 Aug 2021, 18:40 Chris Albertson,
wrote:
> In the general case there may be no closed form solution so numeric
> integration is the only possible solution.I
In the general case there may be no closed form solution so numeric
integration is the only possible solution.I don't think there is any
other way to do it other than numeric integration except to require the
user to supply a function for closed form integrals. But for a 3-axis
mill that
I'm not sure about all this yet, brainstorming here...
After looking at TinyG code for handling jerk limitation in the joint
control it appears that they are using the forward physics equations and
numerically integrating to avoid violations.
Since numerical integration needs to be used for jerk
> On 29 Aug 2021, at 11:40, Alexander Brock wrote:
>
> The idea can be implemented in C and for simple cases like 1D funktions
> it should be fairly straight-forward.
My point is that the kinematics modules already exist, and not all of them are
under our control. Various users’ machines
On 8/26/21 10:38 AM, andy pugh wrote:
> On Thu, 26 Aug 2021 at 00:34, Alexander Brock
> wrote:
>
>> There is an elegant way to compute exact derivatives without computing
>> analytical derivatives by hand. Here is a nice introduction:
>
> Is that applicable to the LinuxCNC kinematics
The software in the link below is very widely used in industry. It is
used inside MoveIt which in turn is driving many complex machines.
https://moveit.ros.org
On Fri, Aug 27, 2021 at 11:52 AM Curtis Dutton wrote:
> That thread leads to this. https://githubhelp.com/pantor/ruckig
>
--
Chris
That thread leads to this. https://githubhelp.com/pantor/ruckig
Pretty interdasting!
On Fri, Aug 27, 2021 at 12:36 PM Andy Pugh wrote:
>
> >> It will require jerk limiting to really get the value out of the
> machine.
>
> There is a jerk-limiting component in the forum
>
>
>
>> It will require jerk limiting to really get the value out of the machine.
There is a jerk-limiting component in the forum
https://forum.linuxcnc.org/47-hal-examples/43401-hal-s-curve-component-for-download-loadrt-dofs-x
It sacrifices path accuracy for jerk limitation (or so I assume) but
how is everyone working out jerk / jolt?
on a stepper motor you have a defined step or micro step (distance)
so if your acceleration is say 3000mm/s/s. (plasma cutter)
and you are driving a 20T mod 1 rack and pinion with a 3:1 ratio drive,
with a 200 step per rev stepper motor on 10uSteps
the
On Thu, 26 Aug 2021 at 00:34, Alexander Brock wrote:
> There is an elegant way to compute exact derivatives without computing
> analytical derivatives by hand. Here is a nice introduction:
Is that applicable to the LinuxCNC kinematics functions? (Which are
kernel modules written in C).
--
atp
On 8/24/21 1:08 AM, andy pugh wrote:
> I have a feeling that kinematics is not a problem in most cases, the
> kins functions run fast enough to be used for finite-difference
> differentiation / numerical integration.
There is an elegant way to compute exact derivatives without computing
Well I have two high speed CNC machines..
But they are all analog control. Probably no good for tinyg
On Thu, 26 Aug 2021, 04:12 dave engvall, wrote:
> IIRC emc was conceived as a vehicle to test intercommunication between
> processes and as such higher level features such as lookahead,
>
So for an abort I think would be still following the proscribed machine
path in a coordinated fashion but stop as fast as possible within
constraints. Sort of like dragging feed override to 0 as quickly as
possible without violating constraints.
For an e-stop it will be an uncoordinated stop.
IIRC emc was conceived as a vehicle to test intercommunication between
processes and as such higher level features such as lookahead,
smoothing, etc were not part of the master plan. In fact emc would not
have had stepping if Matt Shaver had not requested it.
Now on to the real subject of
On Tue, 24 Aug 2021 at 01:54, andrew beck wrote:
>
> Andy do you know what the tormach uses for more than 3 axis path blending?
It's an extension to the circular arc interpolation that went in to
the "new" LinuxCNC TP at 2.7.
--
atp
"A motorcycle is a bicycle with a pandemonium attachment and
So for feed override. I think just having the planner generate a blended
path using the "max' override speed. thus guaranteeing that no constraints
could be violated for any range of the feed override.
Otherwise you would need to regenerate the path based upon override speed
as it changes thus
Andy do you know what the tormach uses for more than 3 axis path blending?
On Tue, Aug 24, 2021, 11:11 AM andy pugh wrote:
> On Mon, 23 Aug 2021 at 21:27, andrew beck
> wrote:
> >
> > Just had a look at tiny g looks great.
>
> I did try to implement a zero look-ahead finite jerk planner for
On Mon, 23 Aug 2021 at 21:27, andrew beck wrote:
>
> Just had a look at tiny g looks great.
I did try to implement a zero look-ahead finite jerk planner for laser
rastering. It was interesting, and I learned a bit.
It is easier the less general you make it.
Ideally LinuxCNC would have a 9-axis
Dunn Inc.
> > 630 Henry Street
> > Dalton, Ohio 44618
> > Phone: (330)828-2105ext. 2031
> >
> > -Original Message-----
> > From: Chris Albertson
> > Sent: Monday, August 23, 2021 3:39 PM
> > To: Enhanced Machine Controller (EMC)
> >
uldn't that also be the same amount
> higher?
>
> Todd Zuercher
> P. Graham Dunn Inc.
> 630 Henry Street
> Dalton, Ohio 44618
> Phone: (330)828-2105ext. 2031
>
> -Original Message-
> From: Chris Albertson
> Sent: Monday, August 23, 2021 3:39 PM
> To: Enh
(EMC)
Subject: Re: [Emc-users] jerk control
[EXTERNAL EMAIL] Be sure links are safe.
On Mon, Aug 23, 2021 at 7:16 AM Todd Zuercher wrote:
> To my lay persons eyes I would think it would be enough to jerk limit
> in joint space. The limiting in Cartesian space would then take care
>
> > have the same acceleration limits as planned motion? Set the jogging
> > > limits to something safe and conservative that won't matter if they are
> > > jerk limited.
> > >
> > > Todd Zuercher
> > > P. Graham Dunn Inc.
> > > 630 Henry St
Dalton, Ohio 44618
> Phone: (330)828-2105ext. 2031
>
> -Original Message-
> From: andy pugh
> Sent: Monday, August 23, 2021 4:50 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] jerk control
>
> [EXTERNAL EMAIL] Be sure links are safe.
>
> On Mon, 2
; >
> > -----Original Message-
> > From: andy pugh
> > Sent: Monday, August 23, 2021 4:50 AM
> > To: Enhanced Machine Controller (EMC)
> > Subject: Re: [Emc-users] jerk control
> >
> > [EXTERNAL EMAIL] Be sure links are safe.
> >
> &
o: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] jerk control
>
> [EXTERNAL EMAIL] Be sure links are safe.
>
> On Mon, 23 Aug 2021 at 04:40, Chris Albertson
> wrote:
>
> > Actually for a machine tool, why not run the simulation off-line and
> > use
Controller (EMC)
Subject: Re: [Emc-users] jerk control
[EXTERNAL EMAIL] Be sure links are safe.
On Mon, 23 Aug 2021 at 04:40, Chris Albertson wrote:
> Actually for a machine tool, why not run the simulation off-line and
> use as much time and computer power as it takes.
Feed-override?
Do you
On Mon, 23 Aug 2021 at 04:40, Chris Albertson wrote:
> Actually for a machine tool, why not run the
> simulation off-line and use as much time and computer power as it takes.
Feed-override?
Do you allow infinite jerk on abort? You might think that is an easy
question, except that continuous
Sent: August-22-21 11:48 AM
> > To: Enhanced Machine Controller (EMC)
> > Subject: Re: [Emc-users] jerk control
> >
> > I have a desire to implement this.
> >
> > My business is in need of another cnc router and I will be building as
> > high speed of
. The path followed now
> is
> > more complex? And which acceleration is used and is it changed as the
> path
> > is followed?
> >
> > What's the goal? To traverse the path as accurately as possible or to
> > reduce the shaking from sudden speed changes (the jerk
but
> make
> > the motion rougher due to acceleration discontinuities. A value in the
> > range 20Hz to 200Hz should be reasonable to start.
> >
> > Finally, no amount of tweaking will speed up a toolpath with lots of
> small,
> > tight corners,
t's the goal? To traverse the path as accurately as possible or to
> reduce the shaking from sudden speed changes (the jerk)?
>
> Mostly just confused.
> John
>
>
>
>
>
> > -Original Message-----
> > From: Curtis Dutton [mailto:curtd...@gmail.com]
-22-21 11:48 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] jerk control
>
> I have a desire to implement this.
>
> My business is in need of another cnc router and I will be building as
> high speed of a machine as I can afford. It is going to be a
t;
> >
> > > -----Original Message-
> > > From: Feral Engineer [mailto:theferalengin...@gmail.com]
> > > Sent: August-17-21 6:46 PM
> > > To: Enhanced Machine Controller (EMC)
> > > Subject: Re: [Emc-users] jerk control
> > >
> > > I'm cu
Message-
> > From: Feral Engineer [mailto:theferalengin...@gmail.com]
> > Sent: August-17-21 6:46 PM
> > To: Enhanced Machine Controller (EMC)
> > Subject: Re: [Emc-users] jerk control
> >
> > I'm curious what the current level of block lookahead is on lcnc comp
C)
> Subject: Re: [Emc-users] jerk control
>
> I'm curious what the current level of block lookahead is on lcnc compared
> to commercial controls. Anyone know the amount of data buffering that it
> can handle?
>
> Phil T.
> The Feral Engineer
>
> Check out my Li
; > > > Here are the most recent threads about jerk-limited trajectory
> > > planning:
> > > > >
> > > > >
> > > > >
> > > >
> > >
> >
> https://forum.linuxcnc.org/24-hal-components/40152-jerk-limited-traj
ing to see this appear in a Linuxcnc update,
> > > > > as it has been worked on by a number of people for years.
> > > > > Here are the most recent threads about jerk-limited trajectory
> > > planning:
> > > > >
> > > > >
> > > > >
> > > >
>
ning:
> > > >
> > > >
> > > >
> > >
> >
> https://forum.linuxcnc.org/24-hal-components/40152-jerk-limited-trajectory-planner-hal-component
> > > >
> > > >
> > > >
> > >
> >
gt; Here are the most recent threads about jerk-limited trajectory
> > planning:
> > > >
> > > >
> > > >
> > >
> >
> https://forum.linuxcnc.org/24-hal-components/40152-jerk-limited-trajectory-planner-hal-component
> > > >
> > > >
> > > >
> > >
> >
t; > >
> > >
> >
> https://forum.linuxcnc.org/24-hal-components/40152-jerk-limited-trajectory-planner-hal-component
> > >
> > >
> > >
> >
> https://forum.linuxcnc.org/38-general-linuxcnc-questions/34666-c2-smooth-velocity-profile?start=0
> > >
> >
2-jerk-limited-trajectory-planner-hal-component
> >
> >
> >
> https://forum.linuxcnc.org/38-general-linuxcnc-questions/34666-c2-smooth-velocity-profile?start=0
> >
> > -- Ralph
> > ________________
> > From: David Berndt [ber...@
: Tuesday, August 17, 2021 9:01 AM
> To: Enhanced Machine Controller (EMC); andrew beck
> Subject: Re: [Emc-users] jerk control
>
> CAUTION: This email originated from outside the Walla Walla University
> email system.
>
>
> I don't have a great need for it with my machines,
From: David Berndt [ber...@uberwin.com]
Sent: Tuesday, August 17, 2021 9:01 AM
To: Enhanced Machine Controller (EMC); andrew beck
Subject: Re: [Emc-users] jerk control
CAUTION: This email originated from outside the Walla Walla University email
system.
I don't have a great need
rofile?start=0
>
> -- Ralph
>
> From: David Berndt [ber...@uberwin.com]
> Sent: Tuesday, August 17, 2021 9:01 AM
> To: Enhanced Machine Controller (EMC); andrew beck
> Subject: Re: [Emc-users] jerk control
>
> CAUTION: This email orig
://forum.linuxcnc.org/38-general-linuxcnc-questions/34666-c2-smooth-velocity-profile?start=0
-- Ralph
From: David Berndt [ber...@uberwin.com]
Sent: Tuesday, August 17, 2021 9:01 AM
To: Enhanced Machine Controller (EMC); andrew beck
Subject: Re: [Emc-users
I don't have a great need for it with my machines, or the time/brains to
implement it. It just seems like a feature we really should have.
I'd be willing to participate monetarily in some sort of system to
incentivize the inclusion of jerk control. Perhaps an open-source feature
bounty?
Forgot to say this is metric of course
On Tue, Aug 17, 2021, 3:53 PM andrew beck wrote:
> Yep g64 p. 01.
>
> This is a high speed vmc so I can't really afford to blend the path more
> than this
>
> On Tue, Aug 17, 2021, 3:48 PM Curtis Dutton wrote:
>
>> Are you using any G64 P- Q- path
It's pretty much a slightly beefier haas vf2
This is a chevalier 2040 vmc
On Tue, Aug 17, 2021, 3:53 PM andrew beck wrote:
> Yep g64 p. 01.
>
> This is a high speed vmc so I can't really afford to blend the path more
> than this
>
> On Tue, Aug 17, 2021, 3:48 PM Curtis Dutton wrote:
>
>> Are
Yep g64 p. 01.
This is a high speed vmc so I can't really afford to blend the path more
than this
On Tue, Aug 17, 2021, 3:48 PM Curtis Dutton wrote:
> Are you using any G64 P- Q- path blending?
>
> On Mon, Aug 16, 2021, 11:19 PM andrew beck
> wrote:
>
> > hey guys
> >
> > I am sitting here
Are you using any G64 P- Q- path blending?
On Mon, Aug 16, 2021, 11:19 PM andrew beck wrote:
> hey guys
>
> I am sitting here watching my cnc mill atm its shaking quite a bit
> acceleration is 600mm/sec2 which is not that high i think. compared to
> every other cnc mill i have used with a
hey guys
I am sitting here watching my cnc mill atm its shaking quite a bit
acceleration is 600mm/sec2 which is not that high i think. compared to
every other cnc mill i have used with a commercial controller. they have
jerk control and work much better. so looking forward to when we get jerk
Yes I already turned them down.
Currently running max velocity at 8m/min and 750mm/sec2 I think.
Which is way slower than it used to run.
On Wed, Sep 23, 2020, 5:50 AM N wrote:
> There are limits in trajectory planner adjustable in .ini file
> DEFAULT_ACCELERATION= and MAX_ACCELERATION= you
There are limits in trajectory planner adjustable in .ini file
DEFAULT_ACCELERATION= and MAX_ACCELERATION= you tried them?
> Hi again,
> Indeed it is pretty hard to use spindle load if is doesn't change thru
> the corner. I suspect it does on smaller machines but that is not a
> generalized
On Tuesday 22 September 2020 02:30:21 dave engvall wrote:
> Hi again,
> Indeed it is pretty hard to use spindle load if is doesn't change thru
> the corner. I suspect it does on smaller machines but that is not a
> generalized solution.
> Just for experimental purposes it might be interesting to
Hi again,
Indeed it is pretty hard to use spindle load if is doesn't change thru
the corner. I suspect it does on smaller machines but that is not a
generalized solution.
Just for experimental purposes it might be interesting to decrease the
velocity thru a corner see if it helps. Lacking the
My first innocent thought was to use a DDT component somehow but I guess
this involves fgpa programming if you're using Mesa boards.
It sounded simple at first but as you think it through it you realize it's
a pain in the ass. Mostly because my only fpga experience is controlling
displays lol.
I
hey dave
I hear you. I might get good at coding myself soon.. but would love to
solve the problem.
I don't think the spindle load could really help much though.
I am machining plastic and aluminium and the spindle load doesn't
noticeably change in corners. I more need a limit on the initial
HI Andrew,
Just because I have ideas does not imply I can implement them. ;-)
However, I believe there is a velocity pin that might be used to slow
down in corners. Since the spindle loads up going thru corners it may be
possible to monitor spindle load and back off velocity thru the corner
Hey guys
just a few thoughts here.
I have a high speed cnc machining center (cnc mill)
it has 16mm pitch ballscrews and weighs 6ton
linuxcnc is awesome and does a great job controlling it. I make plastic
injection molds and lots of 3d machining all the time. plus all the little
jobs that a
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