Dave | 1 Apr 18:05 2012

Trans-Pacific sailboat race that Andy is involved in


Looks like Andy's boat made in to Oakland, CA ok, he was on the 
Derry-Londonderry....

http://www.clipperroundtheworld.com/

But the lagging boat ran into some hard weather and is disabled at sea!

http://www.cnn.com/2012/04/01/us/pacific-yacht-rescue/index.html

Dave

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Dave | 1 Apr 18:13 2012

Re: Trajectory planning and other topics from a, EMC(LinuxCNC) newbie (TheNewbie)

On 3/31/2012 1:43 PM, Peter C. Wallace wrote:
> On Sat, 31 Mar 2012, Dave wrote:
>
>    
>> Date: Sat, 31 Mar 2012 14:20:19 -0500
>> From: Dave<EMC@...>
>> Reply-To: "Enhanced Machine Controller (EMC)"
>>      <emc-users@...>
>> To: "Enhanced Machine Controller (EMC)"<emc-users@...>
>> Subject: Re: [Emc-users] Trajectory planning and other topics from a,
>>      EMC(LinuxCNC) newbie (TheNewbie)
>>
>> My experience with steppers is that once you lose sync with the rotor at
>> speed, you have to slow down tremendously to regain sync with the rotor.
>> So once you start slipping, you are pretty much done as you have lost
>> control of the motor. I don't see how using encoders with steppers
>> really helps other than detecting when you have lost control of the motor.
>>
>> Dave
>>      
> If you have high res encoders and a high enough loop rate (say 30 -50 KHz) and
> a PWM sine/cos drive, you can run step motors as 50 pole 2 phase servos, they
> can never lose steps (as the drive phase is always synced to the rotor) and
> they have ~0 input power at ~0 load torque. However the driver circuits are
> more complicated than 3 phase PMS servo motors (4 1/2 bridges vs 3 1/2
> bridges) and you have still have the same torque/vs speed curve as with a
> normal step drive so unless you need something the the step motors provide
> (low speed torque maybe) step motors make fairly lousy servos
>
>
(Continue reading)

gene heskett | 1 Apr 17:24 2012

Re: Trans-Pacific sailboat race that Andy is involved in

On Sunday, April 01, 2012 11:21:18 AM Dave did opine:

> Looks like Andy's boat made in to Oakland, CA ok, he was on the
> Derry-Londonderry....
> 
> http://www.clipperroundtheworld.com/

Good.

> But the lagging boat ran into some hard weather and is disabled at sea!
> 
> http://www.cnn.com/2012/04/01/us/pacific-yacht-rescue/index.html

Not good.  Disabled in seas like that, they'll either need a tug, or to 
abandon. 400 miles out is a long way for a tug.

> Dave
> 
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Cheers, Gene
--

-- 
"There are four boxes to be used in defense of liberty:
(Continue reading)

Kent A. Reed | 1 Apr 18:48 2012
Picon

Difficulty defining jitter, was Re: May be of Interest

On 3/31/2012 4:45 PM, Kirk Wallace wrote:
> I found this:
> http://www.bitmuster.org/projects/emc.html
>
> the thing that comes to mind, considering the rev date, how it seems
> fairly significant, and recent questions on the list, it's a little
> surprising that this hasn't hit the wiki or been on the lists. Am I
> watching the wrong channels? Might the board want to see that this good
> stuff gets a some promotion? Are there other things going on that are
> worth knowing about?
>
> I'm not judging or suggesting any action (although just a an e-mail
> message with a short title and a link could do wonders:), I'm just
> curious and would like to understand a little more if possible.
Kirk:

Thanks for this. It helped solidify a concern that has been rattling 
around my brain, to wit, how is jitter being defined and measured in 
these different activities. Comparing apples and oranges isn't very 
effective unless one is running a political campaign:-)

I read the last section of the bitmuster document and found the 
following ["EMC2" because of the version involved]:

With a preempt_RT enabled kernel 2.6.33.7.2-rt30 and an appropriately 
modified EMC2.4.4 [patches from Michael Büsch and Jeff Eppler] running 
on an IBM Thinkpad T40 with a 1500MHz PentiumM cpu, the author measured 
the following:
-----
1) the EMC2 latency-test
(Continue reading)

Jan de Kruyf | 1 Apr 18:47 2012
Picon

Re: May be of Interest

Thank you for that link Kirk.
the link looks a bit stale but at the same time it is very much worthwhile
to investigate further.
So I send of an email and downloaded the patches to see what is cooking.

Also I must google the lists a bit because there seems to have been trafic
about it.

By the way Sercos is bragging that old drives can be upgraded with
sercosiii boards without a problem.
So in the light of your findings on Ebay it is worthwhile reseaching this
properly, also for the retrofit market.

j.

On Sat, Mar 31, 2012 at 10:45 PM, Kirk Wallace
<kwallace@...>wrote:

> I found this:
> http://www.bitmuster.org/projects/emc.html
>
> the thing that comes to mind, considering the rev date, how it seems
> fairly significant, and recent questions on the list, it's a little
> surprising that this hasn't hit the wiki or been on the lists. Am I
> watching the wrong channels? Might the board want to see that this good
> stuff gets a some promotion? Are there other things going on that are
> worth knowing about?
>
> I'm not judging or suggesting any action (although just a an e-mail
> message with a short title and a link could do wonders:), I'm just
(Continue reading)

Jon Elson | 1 Apr 20:03 2012

Re: Difficulty defining jitter, was Re: May be of Interest

Kent A. Reed wrote:
>
> With a preempt_RT enabled kernel 2.6.33.7.2-rt30 and an appropriately 
> modified EMC2.4.4 [patches from Michael Büsch and Jeff Eppler] running 
> on an IBM Thinkpad T40 with a 1500MHz PentiumM cpu, the author measured 
> the following:
> -----
> 1) the EMC2 latency-test
>
> Servo Thread: 1ms Max Jitter 261101ns
> Base Thread: 50us Max Jitter 101701ns
>
>   
Well, these are ghastly numbers!  The 1ms thread has jitter of 26% of 
the period, and
the 50us thread has jitter of 204% of the thread period!  That will 
cause system lockups,
I think.

Jon

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Kent A. Reed | 1 Apr 20:55 2012
Picon

Re: Difficulty defining jitter, was Re: May be of Interest

On 4/1/2012 2:03 PM, Jon Elson wrote:
> Kent A. Reed wrote:
>> With a preempt_RT enabled kernel 2.6.33.7.2-rt30 and an appropriately
>> modified EMC2.4.4 [patches from Michael Büsch and Jeff Eppler] running
>> on an IBM Thinkpad T40 with a 1500MHz PentiumM cpu, the author measured
>> the following:
>> -----
>> 1) the EMC2 latency-test
>>
>> Servo Thread: 1ms Max Jitter 261101ns
>> Base Thread: 50us Max Jitter 101701ns
>>
>>
> Well, these are ghastly numbers!  The 1ms thread has jitter of 26% of
> the period, and
> the 50us thread has jitter of 204% of the thread period!  That will
> cause system lockups,
> I think.
>
> Jon
>
I agree, Jon, but that's the different topic I alluded to at the end of 
my reply.

Whether preemption is the right approach or a Thinkpad laptop is the 
appropriate platform or an otherwise unmodified kernel/configuration is 
acceptable are all questions that I can't resolve without using the 
right tools to measure their performance. My point was only that this 
article clearly illustrates the tools differ even when assessing a 
single system so we have to be very careful comparing results measured 
(Continue reading)

Chris Radek | 1 Apr 21:08 2012

RELEASED: LinuxCNC 2.5.0


LinuxCNC 2.5.0 is released!  

You will not get an automatic update from EMC 2.4 to LinuxCNC 2.5.  
To update your Lucid or Hardy machine to 2.5, you need to take a few
steps, documented here:

http://wiki.linuxcnc.org/cgi-bin/wiki.pl?UpdatingTo2.5

Be sure to check the "Changes to your configuration" section at the
bottom of the page.

(I also updated the LinuxCNC Live CD to contain 2.5.0 and to receive
updates from the new 2.5 repository, but the easiest and fastest way
to update an existing install is definitely to follow the instructions
above.  The updated CD will be available sometime later today.)

I want to give my very sincere thanks to everyone who has contributed
to this release.  All of you who have contributed to documentation,
translations, rebranding, new features, and bugfixes should be proud,
and I appreciate you all.

Also I want to especially thank Seb K, who traveled many hours and has
been working with me tirelessly for almost three days solid to get the
final glitches out of the rebranding, packaging, and release process.

Some of the most important changes in 2.5.0 are:

  * AXIS: dynamic tabs can embed other applications, including virtual
    control panels
(Continue reading)

PAUL LIEBENBERG | 1 Apr 21:32 2012
Picon

Re: RELEASED: LinuxCNC 2.5.0

great to hear!  Can someone do a video of the Touchy interface with all the new features please?
Paul

----- Original Message -----
From: Chris Radek <chris@...>
Date: Sunday, April 1, 2012 12:09 pm
Subject: [Emc-users] RELEASED: LinuxCNC 2.5.0
To: emc-users@...

> 
> LinuxCNC 2.5.0 is released!  
> 
> You will not get an automatic update from EMC 2.4 to LinuxCNC 
> 2.5.  
> To update your Lucid or Hardy machine to 2.5, you need to take a few
> steps, documented here:
> 
> http://wiki.linuxcnc.org/cgi-bin/wiki.pl?UpdatingTo2.5
> 
> Be sure to check the "Changes to your configuration" section at the
> bottom of the page.
> 
> (I also updated the LinuxCNC Live CD to contain 2.5.0 and to receive
> updates from the new 2.5 repository, but the easiest and fastest way
> to update an existing install is definitely to follow the instructions
> above.  The updated CD will be available sometime later today.)
> 
> I want to give my very sincere thanks to everyone who has contributed
> to this release.  All of you who have contributed to 
> documentation,translations, rebranding, new features, and 
(Continue reading)

Kent A. Reed | 1 Apr 21:41 2012
Picon

Re: RELEASED: LinuxCNC 2.5.0

As ever, a sincere tip-of-the-hat to you, Chris, Seb, and everyone.

Regards,
Kent

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