Ultra3000 Tuning

Replaced 2 non-AB servo drives with 2 new Ultra3000 Analog drive and AB motors in a 7 year old machine. Controlled by a ControlLogix L1 processor and a MO2AE analog type control module. All Analog control with the drive buffering the Encoder signals back to the servo card. The servo is a dual axis system and is actually a little larger and increased power (100w to 500w) from the old setup.

The problem is in the tuning. I get conflicting advice from TechConnect depending on who I talk to.

What is the best way to do this? Do I do autotuning on the drive first (Velocity Loop) then Autotune the Servo Card. If I do this, then the axis vibrates wildly.

Or do I leave the drive at its defaults and only AutoTune the Card? If I do this, then the axis vibrates wildly.

The only way that I can get it to work is to leave the drive at its defaults, run Autotune then manually cut back the gains and then adjust the parameters in the card unitl it is just below where the unstability starts. It works but the
performance is half of what the old drive did. Checked the current in the drive and its pulling almost nothing. The inertial load is fine when I rechecked all the calculations.

When I do a trend graph, my positional error is substantial but trying the standard tricks to adjust it only results in increased ringing or the motor becomes unstable. Had the local distr. rep in and they couldn't tune it either. They keep telling me that I should have put in a serco's system. However, the old system was working fine, but we can't get the drives anymore so we thought it would have been safe to install an AB drive on an AB PLC.

This should work. Has anyone else used the Analog 3000's? What is the best way to tune this?

Just in case someone else has the same problem. When using the drive with an Analog control such as the M02AE, the drive needs to be set in Torque or Current mode. Depending on what documentation you read, they interchange the terms. No Tuning is required in the drive.

ATU said:

Just in case someone else has the same problem. When using the drive with an Analog control such as the M02AE, the drive needs to be set in Torque or Current mode. Depending on what documentation you read, they interchange the terms. No Tuning is required in the drive.

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You must have been using the velocity loop in the drive and then tried to do auto tuning for torque mode in the M02AE. I can see why that wouldn't work well. I would need to think about it as to why it didn't work at all. Interesting.

A good auto tuning ( system identification ) algorithm would have been able to notice the mode the drive is in and adjust accordingly. For us the biggest difference between drives in torque mode and drives in velocity mode is how one excites the system so the auto tuner still must know up front which mode the drive is in.