Author Topic: Tempest Planning - Preliminary information and testing  (Read 274234 times)

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Offline ART

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Re: Tempest Planning - Preliminary information and testing
« Reply #120 on: February 05, 2010, 08:05:11 PM »
>>There'd be no need to, the plugin author coudl just a load a file of points..

Art

Offline piv

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Re: Tempest Planning - Preliminary information and testing
« Reply #121 on: February 06, 2010, 12:06:27 AM »
Thats what I thought might be possible, loading a file of points straight to the device. Even better if can happen from inside the G code file somehow as the machine has to work like a normal machine, for tool changes, set up, jogging, MDI, fixture offset etc. DSPMC plugin was written by Vital Systems. Im going to see if they can do anything or help out.  I asked the question yesterday but havent got an answer from Rufi yet.

Id be willing to have a go at the plugin.  Can you give me a bit of architectural guidance or point me to a document that says whats possible, or how it could happen as Ive never written a plugin. Im not sure on how I could get it to work with the DSPMC, Ive got no documentation on the communication to it.

Offline ART

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Re: Tempest Planning - Preliminary information and testing
« Reply #122 on: February 06, 2010, 08:21:22 AM »
piv:

   Theres a few docs around on plugins.. check the plugins download sdk for the example, but you migth ask rufi if he'd give you a copy of
his current one..

Art

Offline piv

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Re: Tempest Planning - Preliminary information and testing
« Reply #123 on: February 07, 2010, 03:06:52 AM »
Rufi from Vital Systems, DSPMC is going to help me out with this.  Thanks Art.

Offline Bruce Griffing

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Re: Tempest Planning - Preliminary information and testing
« Reply #124 on: March 22, 2010, 10:09:45 AM »
  I have a couple of questions about Tempest.  I have read the thread up to this point and I am not fully clear on the reasons for Tempest.   As a physicist, I do understand jerk and snap.  I also appreciate the fact that what you are doing will make the Mach3 machines run "more smoothly".   But what are the specific ends you are trying to achieve?   Better looking results on the workpiece? Less wear on the machine?  More axes? Less error in the cut path?  I ask because it is helpful to fully understand the objectives when testing.   It will help me select test parts from parts I am making.
 My second question relates to processors.  Is this module designed to take advantage of multiple processors?   My desktop now has 4 cpu's (8 if you count hyperthreads).   More will come in the future.

Offline ART

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Re: Tempest Planning - Preliminary information and testing
« Reply #125 on: March 22, 2010, 10:23:04 AM »
Hi:

  >>But what are the specific ends you are trying to achieve?

 All of the things you mention really. The problem lies in the way planners typically plan a motion. When acceleration is applied, its applied fully
until the motors get up to speed, when decelerating, the decel is applied at full rate to slow down. This causes "Jerk", the immediate slowing down of mass
which causes a jerk on the motors and mechanics.
  Tempest applies the accel is a sine wave template, so its much smoother. Its an attempt to make motion in cnc more like driving a car where the accelerator
is pressed in an analogue motion dependingh on requirement.

  As the thread says though, this makes most motion take up to 30% longer.. the guy  with the binary accelerator pedal DOES get to his destination faster,
but its harder on the vehicle and brakes. The challenge usually is the small segement code, where its hard to concatenate small segments to move quickly.

 Tempest is an experiment producing 5th order waveforms instead of 3rd order as is typical. It does achive less error in the pah, smoother motion and defined
limits in mechanical stress, but at the  expense of speed. MOre work willlikely be done this summer to see what can be done to address the time compnents.

Art

Offline Bruce Griffing

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Re: Tempest Planning - Preliminary information and testing
« Reply #126 on: March 22, 2010, 10:44:34 AM »
I think you could recover some of the lost time Tempest "costs" in the following way.   Mach3 presently does the acceleration setup from a standing start.   I believe you can, for most machines, achieve greater acceleration from a moving start due to higher static than dynamic friction.  Since Tempest will limit jerk, the starting acceleration will be smaller than the peak acceleration.   Allowing for margin in both cases, my guess is that a machine set up to take advantage of this fact could make a substantial improvement in Tempest mode over standard setup in standard mode. 

Offline Bruce Griffing

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Re: Tempest Planning - Preliminary information and testing
« Reply #127 on: March 22, 2010, 12:09:57 PM »
I noticed the wording in my last sentence was not what I intended.   What I meant was that with the alternate setup I proposed, Tempest would be better than Tempest without the alternate setup.  I don't think you could reach the performance of Mach3 with its infinite jerk.  You could, however, recover some of the loss relative to stock Mach3.

Offline ART

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Re: Tempest Planning - Preliminary information and testing
« Reply #128 on: March 22, 2010, 12:19:38 PM »
>>Mach3 presently does the acceleration setup from a standing start.   I believe you can, for most machines, achieve greater acceleration from a moving start due to higher static than dynamic friction.


   I may not be understanding your intent. Its true that MAch3 applies accel from a standing start, it goes from 0 accel to max accel instantly...
Tempest applies it gradually. But both tempest and mach3 apply accel from moving start on every block as its in motion.. tempest gradually, mach3 instantly..

  Its mostly a tradeoff with any scheme, but Tempest is a test of the tradeoffs..

Art
 

Offline Bruce Griffing

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Re: Tempest Planning - Preliminary information and testing
« Reply #129 on: March 22, 2010, 12:58:43 PM »
The setup of acceleration in M3 is done starting at rest.   The user tunes the acceleration based on how the machine performs in this test - with no control of jerk (pretty high at end points) as I understand the test.   As it says in the docs - the limit is set mostly done by sound and pushing to failure and them backing off.    I believe that if the setup were done with a jerk limit, the peak acceleration that the user would end up with would be higher than the acceleration you end up with in the standard test.   This is because higher peak accelerations would be possible since they would occur (in the test) when the machine was already moving.  This of course implies a different acceleration setup for Tempest M3 than stock M3.  Is that clear?