Oscillation at idle

[jimbit22]

Hi, I have a question regarding Argon regarding Oscillation at idle .

My hardware configuration:
-ARGON
-CONTROL TECHNIQUES 075U2D305BAEBA075140
-2110
-18M long cable
Encoder: heidenhein eqn 1325 1vpp sin/cos and endat01

Problems arise when:
After torque mode setting when i change to velocity mode the motor starts vibrating without a set point.
if i input a set point the motor starts to rotate correctly but without the vibrations.

How it behaves:
-oscillation without load.
If is set [KVP] to 5 it stops oscillating.

How I would expect it to behave:
Stay still

I have attached following files:
-(consider adding saved Granity configuration file .drc)
-(screenshots)

I also would like to share that (additional info).
the ferrite core on the servo cables is getting warm.
encoder cable: stuttgart olflex servo fd 798 4x2 twisted pairs shielded
connectors:m23
servo cable: 4x2mm3 plus 2x1mm3 independently shielded orange servo cable

i have resistance and inductance values from the motor manufacturer

i have 2 similar motors with the same encoder/ pole count and i tested them both and appear the same symptoms.

I have installed 120 ohm termination resistors on the (A+ A- )(B+ B-)

ferrite installed on 3 servo phase cables and on power input
mains power filter siemens 3 phase and neutral 65a

i have double checked grounding on everything.
Drive chassis is grounded
All servo cables are grounded on the ground conductor and both shields
Encoder cable shield is grounded on the connector

I have checked insulation resistance on the motor and servo cable with everything disconnected. Multimeter 200Mohm. Checks:
Phase to phase
Phase to GND
Phase to shield
Motor case to motor phase
Motor brake to phase
all good

Position feedback (raw) is rock stable when the drive is not enabled.

Thank you for your time,
Dimitris

[jimbit22]

the drive is enabled here on velocity mode:

the drive is not enabled here:

[jimbit22]

one more capture at a setpoint ~ 24r/min with oscillations:

and with the same settings without oscillations with the setpoint at max rpm:

[Esa]

Hi Jimbit

This looks like tuning issue. Please read our tuning guide and the two other wiki links under this.

https://granitedevices.com/wiki/Servo_motor_tuning_guide
https://granitedevices.com/wiki/Essential_Basics
https://granitedevices.com/wiki/Servo_motor_torque_mode_test

Kind regards, Esa

[jimbit22]

Yes it is a tuning issue, I got it somewhat tuned.

I believe the cable length of 18 meters makes it very unstable since there are no settings for a dead zone.

To get it working I had to set the sin/cos resolution to x16.
At this resolution the drive recognises half the lines of the encoder. So the 2048 line encoder is recognised as 1024. At this setting the system is stable at a max P value of 30.
If I set the resolution to x64 it recognises the full 2048 lines but it is unstable on any P value over 8.

Is something I’m I missing except the articles you mentioned above?

[Esa]

Hi Jimbit

Are the motor and encoder cables shielded? And ferrite cores added to phase wires? Long cable is more likely to cause signal issues to logic level signals, especially to analog sincos.

[jimbit22]

hi,

Yes, everything is shielded and professional grade. Cables connectors everything…
Ferrite cores are on the supply side and the 3 servo phases.

All shields are grounded.

This is a 7 axis gantry cnc mill everything is professional grade.

I did a retrofit on this machine i changed all servos to delta servos but the a axis motor is unique and i could not find a replacement so i am trying your drive to this motor.

To get it to tune i have set my coil resistance to 1.200 ohm (7.5 ohm measured at the motor)
and the coil inductance to 30.000 mH from a 19,700 stated by the manufacturer.