Dynomotion

Group: DynoMotion Message: 15210 From: kn6za Date: 12/8/2017
Subject: retrofit of velocity loop servo system

I have a system I am looking to retrofit the kflop/kanalog into. It currently has yaskawa servo amps in velocity mode with tach feedback, +-10v control signal.


Question is, will I be able to use these amps. The only experience I have is with amps in torque mode, and I dont know what kind of difficulty these amps will present in the tuning process.



 Thanks.


    Andrew
Group: DynoMotion Message: 15211 From: Tom Kerekes Date: 12/8/2017
Subject: Re: retrofit of velocity loop servo system
Hi Andrew,

I'm assuming the Yaskawa Amps have differential encoder outputs as most do.

Yes you should be able to use the Amps.  Velocity mode is typically easier to tune than Torque/Acceleration mode if the Amplifier has a well tuned velocity loop.  Usually only P gain is required.  It's like controlling the speed of a car to be proportional to the distance to a stop sign.  Go slower as you get closer.  This results in a nice exponential curve to a stop at the target.  Whereas Torque/Acceleration mode with P gain only would result in max speed as the car passes the stop sign.  So Damping/D Gain/Lead Compensation is required to have a stable system.

The Yaskawa Amps probably have an option to operate in Torque mode if you prefer this.

HTH
Regards
TK

On 12/8/2017 3:39 PM, kn6za@... [DynoMotion] wrote:
 

I have a system I am looking to retrofit the kflop/kanalog into. It currently has yaskawa servo amps in velocity mode with tach feedback, +-10v control signal.


Question is, will I be able to use these amps. The only experience I have is with amps in torque mode, and I dont know what kind of difficulty these amps will present in the tuning process.



 Thanks.


    Andrew
Group: DynoMotion Message: 15212 From: Federico Javier de la Cruz Riz Date: 12/8/2017
Subject: Re: retrofit of velocity loop servo system
I have done a similar retrofit with Meldas drive amps and dc motors with tachometers in a Mazak VQC-15. The tachometers still connected to the drives and as Tom said, the tunning process is quite easy. I just did some trial runs without the belts, just to see if the driver reponse to the signal was linear. The only thing i did have some trouble was with one drive oscilating, but it was the feedback inverted from tachogenerator.
As a position feedback i was able to use the original resolvers, with almost no effort.
Federico.

El 8 dic. 2017 8:39 PM, "kn6za@... [DynoMotion]" <DynoMotion@yahoogroups.com> escribió:
 

I have a system I am looking to retrofit the kflop/kanalog into. It currently has yaskawa servo amps in velocity mode with tach feedback, +-10v control signal.


Question is, will I be able to use these amps. The only experience I have is with amps in torque mode, and I dont know what kind of difficulty these amps will present in the tuning process.



 Thanks.


    Andrew
Group: DynoMotion Message: 15213 From: kn6za Date: 12/8/2017
Subject: Re: retrofit of velocity loop servo system
Tom and Federico,


   I appreciate the experienced advice from both of you. I shall proceed with this retrofit and keep the amps.

   The encoders sadly are single ended. Its not that big of a deal as they are currently 12volt and 750 line. I guess I could add a line driver and use the existing encoders, but i would like a higher line count, so I will fit some 2500 line units from usdigital with a line driver.

  This is a matsurra mc500 that needs the kmotion for a new lease on life!


   Thanks
     Andrew