Hello Steve:
Just a suggestion to help you figure this out.
It sounds like you have some issue with integral gain in the K flop and possibly with your tach gain setting on your drive.
FYI, I've found best success and performance in Tach mode on analog drives when tach feedback was available so I would continue in Tach mode as you have now.
I would start by setting integral gain to 0 to see what happens.
If your original drive was working OK before you replaced it, I would suspect that your Tach gain adjustment on the amp or overall amp gain is too low.
You could try just adjusting the amp gain pot on the amp.
Does the AMC servo amp instructions describe an adjustment procedure for these gains?
If so, I would go through that procedure with the motor coupling disconnected .
The procedure I use is as follows:
Set the pots on the drive to the recommended starting point. Usually about the middle of travel on all except the Gain. That one is usually one turn above minimum.
First adjust Tach gain:
Determine what your maximum axis speed will be at the motor. Lets Say 500 inches per minute is your max speed and the motor needs to run 1000 rpm to acheive this. This is dependent on machine gearing etc.
In Tach mode you want to acheive this speed 1000 rpm with a 10 volt analog command. ( By the way, all your axes should be set so they all achieve the same inches per minute with the same analog command value.) This makes for better contouring performance.
With a tach on the motor, you would simply measure the voltage coming out of the tach with a voltmeter to determine the actual speed of the motor. You need to know the tach specification to do this. Many tachs are spec'd at 7 volts per 1000 rpm but this can vary by manufacturer.
So set the analog command to 10 volts and adjust the Tach potentiometer to achieve the desired speed at the motor.
in this case 1000 rpm or with a 7 volt tach, 7 volts at the tach leads.
Now you can set the overall gain or response potentiometer.
I normally set this by setting the command to 0 volts and increasing the gain pot until the motor starts oscillating or humming. Then I turn the gain pot back to reduce the gain until the oscillation stops and then reduce the gain an additional two turns.( assuming a 10 turn or more pot)
Your adjustment should now be very close.
To verify your setting I check the motor response by hand:
In Tach mode, with no command and no encoder feedback, the motor should stand still or drift slightly (<1 rev per 5 seconds).
If the motor is drifting faster than this just adjust the null or balance pot.
If you were to try to turn the motor shaft by hand the motor should fight you firmly but not oscillate.
Good luck.
AZ
| Group: DynoMotion |
Message: 10086 |
From: Tom Kerekes |
Date: 9/1/2014 |
| Subject: Re: Help with a servo drive |
Hi Steve,
Not sure what that might be. Maybe the Amplifier disabling and then re-enabling? How fast is the cycle repeating?
I would suggest using the KMotion Step Response Screen to diagnose what is happening. Make a Z "Move" of zero size (for max time of 3.5 sec) and plot Command, Position, Output vs time. The Plot should provide clues what is going on. Post a screen shot here along with the raw data saved as a text file.
HTH Regards TK
| Group: DynoMotion |
Message: 10087 |
From: Steve Klemp |
Date: 9/1/2014 |
| Subject: Re: Help with a servo drive |
Thanks Tom. I will test it and post the results. |
| | | |
