Dynomotion

Group: DynoMotion Message: 752 From: cncman172 Date: 11/7/2010
Subject: KFLOP CALCULATIONS
Tom,

OK, after some more playing here is what I discovered.

KFLOP is using quadrature encoder counts.

I sent my amplifier to use 2000 P/R after adjusting the electronic gearing divisor.

Now if I tell it to move 8000 pulses it moves one revolution.

If I use that as a data point then my calculations for a 3000 RPM motor should be as follows:

3000 RPM = 50 REV/SEC

ENCODER = 2000 PUL/REV * 4 QUAD = 8000 PUL/REV

50 REV/SEC * 8000 PUL/SEC = 400,000 Pulses/Sec MAX SPEED

Does this math agree with your calculations?


I guess the next steps will be to start setting up the C-code.
I notice when I click on each thread link there is a sample C program on each thread. I am assuming none of these are running because I have not compiled anything yet. Do I just delete this code? I notice there is a sample for a simple 3 or 4 axis mill. Just planning ahead so I can keep reading on the right way to do things. ha ha

Russ
Group: DynoMotion Message: 753 From: Tom Kerekes Date: 11/8/2010
Subject: Re: KFLOP CALCULATIONS
Hi Russ,
 
Yes 400,000 steps/sec looks correct.  The next thing would be to test what acceleration works well with your system.  I'd start with an acceleration of 400,000 steps/sec^2.  This will result in the acceleration to full speed occuring over 1 second.  Then increase or decrease to what seems fast enough but doesn't shock your system too much.  Always keep the Jerk setting to be 100X the Acceleration value to simulate the infinite jerk motion that Mach3 uses.  Yes Mach3 ramps the velocity up and down linearly according to what acceleration you specify in "Motor Tuning".  But full acceleration is applied instantly.  This is somtimes referred to as a trapazoidal velocity profile.  Jerk refers to something else.  When Jerk is limited, the acceleration is linearly ramped and the velocity profile forms an "s" curve.  Actually there is a special version of Mach3 called "Tempest" that attemps to perform Jerk limited motion, but not many users are using it.
 
Regards
TK

Group: DynoMotion Message: 758 From: cncman172 Date: 11/10/2010
Subject: Re: KFLOP CALCULATIONS
Tom,

I set the velocity and acceleration to 400K and the Jerk to 100x that as you suggest. On the bench the motor seems to spin fine but I did notice something that looks like over shoot.

More detail.

I tell the motor to move 8000 pulses and it rotates to the right one revolution and the motor has a coupler on it with a fine line so i put a piece of tape on the table to ensure it goes one revolution and stops. Moving right it stops right on the line then reverses it seems to just over shoot on the counter clockwise rotation and then the servo corrects and moves clockwise back to the line.

I tuned the panasonic servo with the panasonic amp and it seemed perfect. I need to do more experimentation to determine if this is coming from the Kflop or I need more adjustment on my amp. The motor is under a no load situation and I will try another motor and possibly another amp but seems to be overshooting.


Russ


--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Russ,
>
> Yes 400,000 steps/sec looks correct.  The next thing would be to test what
> acceleration works well with your system.  I'd start with an acceleration of
> 400,000 steps/sec^2.  This will result in the acceleration to full speed
> occuring over 1 second.  Then increase or decrease to what seems fast enough but
> doesn't shock your system too much.  Always keep the Jerk setting to be 100X the
> Acceleration value to simulate the infinite jerk motion that Mach3 uses.  Yes
> Mach3 ramps the velocity up and down linearly according to what acceleration you
> specify in "Motor Tuning".  But full acceleration is applied instantly.  This is
> somtimes referred to as a trapazoidal velocity profile.  Jerk refers to
> something else.  When Jerk is limited, the acceleration is linearly ramped and
> the velocity profile forms an "s" curve.  Actually there is a special version of
> Mach3 called "Tempest" that attemps to perform Jerk limited motion, but not many
> users are using it.
>
> Regards
> TK
>
>
>
>
> ________________________________
> From: cncman172 <rdlarson@...>
> To: DynoMotion@yahoogroups.com
> Sent: Sun, November 7, 2010 2:28:24 PM
> Subject: [DynoMotion] KFLOP CALCULATIONS
>
>  
> Tom,
>
> OK, after some more playing here is what I discovered.
>
> KFLOP is using quadrature encoder counts.
>
> I sent my amplifier to use 2000 P/R after adjusting the electronic gearing
> divisor.
>
> Now if I tell it to move 8000 pulses it moves one revolution.
>
> If I use that as a data point then my calculations for a 3000 RPM motor should
> be as follows:
>
> 3000 RPM = 50 REV/SEC
>
> ENCODER = 2000 PUL/REV * 4 QUAD = 8000 PUL/REV
>
> 50 REV/SEC * 8000 PUL/SEC = 400,000 Pulses/Sec MAX SPEED
>
> Does this math agree with your calculations?
>
> I guess the next steps will be to start setting up the C-code.
> I notice when I click on each thread link there is a sample C program on each
> thread. I am assuming none of these are running because I have not compiled
> anything yet. Do I just delete this code? I notice there is a sample for a
> simple 3 or 4 axis mill. Just planning ahead so I can keep reading on the right
> way to do things. ha ha
>
> Russ
>
Group: DynoMotion Message: 759 From: Tom Kerekes Date: 11/10/2010
Subject: Re: KFLOP CALCULATIONS
Hi Russ,
 
It is  almost certainly your Amp.  Using Step/Dir Mode KFlop is not part of the Servo loop.  It just generates a perfect trajectory with no overshoot (the blue plot).
 
Regards,
TK