DMM DYN4 Paired Y axis motors fighting one another

[slodat]

As the subject says.. got my DMM DYN4 servo conversion powered up tonight for some testing. Things were going pretty well. I tuned the X and Z axis servos. I disconnect the Y2 (slave to Y in Acorn) servo power while I tuned Y axis servo. It started to whip the gantry a bit more than my comfort level, so I cancelled the tuning. As a best guess, I entered the X axis tuning values into the Y and Y2 drives. They have the same drive components.

Now, the two motors are acting up. I attached a video showing what's going on. It's like they are fighting each other.

I attached a fresh report. Photos of my router are in the two threads in my signature. I have DMM's DYN4 cables and they are wired IAW DMM's schematic.

I feel like what is going on is because of the tuning. I can't see that tuning program not causing some sort of damage to my gantry. Either way, once I move the Y axis in CNC12, the two Y axis motors starting making a progressively louder "servo noises". If I hit the E-Stop in CNC12, and then reset, all is good until I move the Y axis again.

https://youtu.be/oUfIZDmwchU

[JoeG]

Post a snip of the tuning values for the Y axis servos.

Start by reducing the 2 gain (main & speed) values by half. Then increase them slowly on both Y servos until you get some noise (increase both gains in both servos and move), reduce to ~85% and then try moving it in CNC12.

Most auto tunes tend to tune a little too gainy,

JoeG

[slodat]

Main: 25
Speed: 22
Integration: 1
Torque Filter Constant: 127
Max Acceleration: 12
Max Speed: 24

Gear Number: 2000
Line Number: 500

[JoeG]

Increase the integration gain to ~20

Decrease the main gain by half and the speed gain by 3

JoeG

[JoeG]

Maybe only 10 on the integration gain....

[JoeG]

Another thing would be to use a much higher gear number, this will give smother operation especially if the Y axis is rack and pinion.

Also try to use natural binary numbers, 512, 1024, 2048 etc. I am using a gear number of 2048 (8192 ppr) on ball screws, on a rack and pinion use as high a gear number as you can stand.

JoeG

[slodat]

Thank you for the help!

Looks like I have it isolated to a bad motor. I noticed when I bench tested everything that one motor had a bit of a hum to it that the other three did not have. I installed it in my Z axis because it would be the easiest to replace if there is indeed an issue with the motor. Well... I've isolated my problem to that motor.

If I power down the drive associated with that motor, everything operates great on the other three drive/motor pairs. I swapped that motor to another drive and the problem persists. No matter which drive I have the suspect motor connected to, I have the issue if the drive is powered up. I'm calling the motor bad because the problem follows the motor on any of my drive/cable combos.

[slodat]

https://youtu.be/N3EXgxe40ek