Dynomotion

Group: DynoMotion Message: 14387 From: az9633@ymail.com Date: 2/13/2017
Subject: FRO acc . dec rates
Tom:
Is there a parameter that limits the acc and dec rates with the Hardware FRO in version 4.33?
  The instant FRO feature is great!  My machine  jerks when the FRO is changed at the .05 sec rate per the POT FRO example. :I'm looking for a way to smoothly limit the rate of change of the feedrate when the FRO pot is changed faster than the machine acc dec rates.
Any suggestions?

AZ
Group: DynoMotion Message: 14391 From: Tom Kerekes Date: 2/13/2017
Subject: Re: FRO acc . dec rates

Hi AZ,

I'm not really sure I understand what the issue is.

The rate FRO (and Feedhold) is applied is determined by your max velocities, accelerations, and Jerks for the axes involved.  If you make those settings less aggressive then the FRO should be applied less aggressively.

Otherwise you could change the SetFRO.c program to more gradually make the FRO adjustment.  For example instead of commanding the new FRO setting every 0.05sec you might just adjust the new FRO by some amount (1% ?) closer to the desired FRO.  In this case if the user rapidly changed the FRO it would gradually ramp to the new rate over some time period (ie 1 second).

HTH

Regards

TK


On 2/13/2017 1:15 AM, az@... [DynoMotion] wrote:
 

Tom:
Is there a parameter that limits the acc and dec rates with the Hardware FRO in version 4.33?
  The instant FRO feature is great!  My machine  jerks when the FRO is changed at the .05 sec rate per the POT FRO example. :I'm looking for a way to smoothly limit the rate of change of the feedrate when the FRO pot is changed faster than the machine acc dec rates.
Any suggestions?

AZ
Group: DynoMotion Message: 14414 From: az@aimele.com Date: 2/16/2017
Subject: Re: FRO acc . dec rates
Tom:

Just to be clear. Did you mean that the FRO rate of change is applied based on the individual axis acc/ jerk rates not on the coordinate system rates?

What happens in a coordinate system when there is a coordinated motion like a circle being executed where the speeds on each axis are different and
the FRO is changed? Does each axis Acc/dec at different rates based on their own max acc / dec (which may be different) or does the coordinate
system rate of change take on acc/dec rates of one of the axes in the system therefore preserving the coordinated path?

Thank you for the suggestions.

AZ.




Group: DynoMotion Message: 14415 From: TKSOFT Date: 2/16/2017
Subject: Re: FRO acc . dec rates
Hi AZ,

All the Individual Max Velocities, Accelerations, Jerks specified in
KFLOP (not the trajectory planner) of all the Axes in the coordinate
system are considered to determine how fast to change the FRO. The Axis
that takes the longest time to stop from its Maximum Velocity will be
what determines the rate. Because by the time we stopped (or fully
changed the FRO) some or all of the axes may have accelerated to higher
speeds based on the path direction, feedrates, accelerations, etc. KFLOP
uses the worst case rate for the longest time to stop axis.

The motion along the coordinated path will be exactly preserved.

HTH
Regards
TK


On 2017-02-16 10:38, 'az@...' az@... [DynoMotion] wrote:
> Tom:
>
> Just to be clear. Did you mean that the FRO rate of change is applied
> based on the individual axis acc/ jerk rates not on the coordinate
> system rates?
>
> What happens in a coordinate system when there is a coordinated motion
> like a circle being executed where the speeds on each axis are
> different and
> the FRO is changed? Does each axis Acc/dec at different rates based on
> their own max acc / dec (which may be different) or does the
> coordinate
> system rate of change take on acc/dec rates of one of the axes in the
> system therefore preserving the coordinated path?
>
> Thank you for the suggestions.
>
> AZ.
>