Dynomotion

Group: DynoMotion Message: 2644 From: sparky300013 Date: 12/8/2011
Subject: Where to start tuning?
Hello every one.

I have been playing with the K Flop and Snap Amp. I am having a hard time figuring out where to start with motor tuning.
I have a brushed dcmotor from Keling nema23 with a 1250CPR encoder.
That gives me 5000PPR, ball screw is .125 lead, now I want to go 100 IPM

I am having the hardest time understanding the math and how to figure out what numbers need to be pluged into where. I have read the help pages many times. And searched through all the post on here. I need dummy instructions. I have tried examples that others have posted in the files area for a DAC servo, thinking it would be a close start. But I really want to understand what needs to be done and how it needs to be calculated.

I dont know where to start with the Velocity, acceleration, and Jerk. I do understand the PID part of the equasion, as far as it relates to a Gecko style drive. But this drive is a little different.

I really don't understand what the max limits do either. But I do know I when I change one of those settings it does change the way the motor responds. Too little on the Integrator and it goes nuts.

Any body know a good book as it relates to a KFlop.

Thank You
Robert.
Group: DynoMotion Message: 2645 From: Tom Kerekes Date: 12/8/2011
Subject: Re: Where to start tuning?
Hi Sparky,
 
I think your resolution comes out to 40,000 counts/inch.  So the Velocity would be 100/60x40000=67000 counts/sec.
 
To accelerate to full speed in 1/2 sec would require 133000 counts/sec^2 acceleration
 
To apply the acceleration in 1/10th sec would require 1,330,000 counts/sec^3 of Jerk
 
But start off lower on velocity and acceleration until things are working well.  Then increase things to see what your system can handle.
 
Max Output - limits the max output of the servo which in the case of a SnapAmp will limit the max current applied to the motor.  This should be set as low as possible to achieve the acceleration that you really need.
 
Max Integrator - limits the amount the integrator to "wind up".  Without any limit if something abnormal happens like if you force the servo off target with your hand and hold it off for a long time the integrator will continue to ramp up to a Huge value so then if you release it there will be a large overshoot most likely slamming the axis into the limit (this assumes you don't have a Max Following Error set to fault the axis).  Max Integrator helps prevents this.  Normally it should be set to a fraction of the Max Output.
 
Max Error - Normally servo following errors are small.  But in abnormal situations they might be big such as when trying to accelerate too fast.  Max Error can limit the amount of error that the servo "sees" so as not to react too violently to a huge error.  This should normally be set to slightly bigger that the amount of errors that you would expect under normal conditions. 
 
Judleroy has a SnapAmp and Brush Servos and started a servo tuning thread on CNCZone.  See:
 
 
Regards
TK 
 
 

Group: DynoMotion Message: 2717 From: sparky300013 Date: 12/14/2011
Subject: Re: Where to start tuning?
Hello Tom,

I checked out the thread on CNC Zone. But I did not want to clutter his thread up with my pictures. So I statrted a new on one servo tuning. with alot of pictures.

Have a look if you get the chance. The first post was the origional tuning where I started the second post I started over.

Thank you
Rob

--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Sparky,
>  
> I think your resolution comes out to 40,000 counts/inch.  So the Velocity would be 100/60x40000=67000 counts/sec.
>  
> To accelerate to full speed in 1/2 sec would require 133000 counts/sec^2 acceleration
>  
> To apply the acceleration in 1/10th sec would require 1,330,000 counts/sec^3 of Jerk
>  
> But start off lower on velocity and acceleration until things are working well.  Then increase things to see what your system can handle.
>  
> Max Output - limits the max output of the servo which in the case of a SnapAmp will limit the max current applied to the motor.  This should be set as low as possible to achieve the acceleration that you really need.
>  
> Max Integrator - limits the amount the integrator to "wind up".  Without any limit if something abnormal happens like if you force the servo off target with your hand and hold it off for a long time the integrator will continue to ramp up to a Huge value so then if you release it there will be a large overshoot most likely slamming the axis into the limit (this assumes you don't have a Max Following Error set to fault the axis).  Max Integrator helps prevents this.  Normally it should be set to a fraction of the Max Output.
>  
> Max Error - Normally servo following errors are small.  But in abnormal situations they might be big such as when trying to accelerate too fast.  Max Error can limit the amount of error that the servo "sees" so as not to react too violently to a huge error.  This should normally be set to slightly bigger that the amount of errors that you would expect under normal conditions. 
>  
> Judleroy has a SnapAmp and Brush Servos and started a servo tuning thread on CNCZone.  See:
>  
> http://www.cnczone.com/forums/dynomotion_kflop_kanalog/142000-optimizing_servo_tuning.html
>  
> Regards
> TK 
>  
>  
>
> From: sparky300013 <rwclark@...>
> To: DynoMotion@yahoogroups.com
> Sent: Thursday, December 8, 2011 4:44 PM
> Subject: [DynoMotion] Where to start tuning?
>
>
>  
> Hello every one.
>
> I have been playing with the K Flop and Snap Amp. I am having a hard time figuring out where to start with motor tuning.
> I have a brushed dcmotor from Keling nema23 with a 1250CPR encoder.
> That gives me 5000PPR, ball screw is .125 lead, now I want to go 100 IPM
>
> I am having the hardest time understanding the math and how to figure out what numbers need to be pluged into where. I have read the help pages many times. And searched through all the post on here. I need dummy instructions. I have tried examples that others have posted in the files area for a DAC servo, thinking it would be a close start. But I really want to understand what needs to be done and how it needs to be calculated.
>
> I dont know where to start with the Velocity, acceleration, and Jerk. I do understand the PID part of the equasion, as far as it relates to a Gecko style drive. But this drive is a little different.
>
> I really don't understand what the max limits do either. But I do know I when I change one of those settings it does change the way the motor responds. Too little on the Integrator and it goes nuts.
>
> Any body know a good book as it relates to a KFlop.
>
> Thank You
> Robert.
>