AxisWorks tuning

[TOTALLYRC]

Hi Peter,
Your PID looks like way too much I and not enough D.

I think the manual suggests as a starting point a ratio of  20:1 D to P. This means that if your P is 8000 your D should be 160,000/ I normally start with an I of 0 and then you can try slowly adding some in. I also run my amps in torque mode. IIRC velocity mode is better when running slow.

Mike

[peter81]

Hi Mike,

If I set D in X-axis 25 times higher than P I instantly met follow error and must set max error to 5000 to execute motion without error and overshoots the final position for 30 to 40 counts.

[TOTALLYRC]

Hi Pete,
Set your scale at 100,
I at 0
P 5000
D 10000.
Set the following error at 1000.
accel at 20 IPS. Max  velocity of 100 IPM
Let me know what happens.

It looks like you are using MM not inches. Your accel is set at 1500mm per sec/sec. or 60 in/sec.
 I would try 500 mm/sec/sec or 20 in/sec/sec.

You will reach a point where you will sacrifice accel for speed or vise versa or you will have to keep opening up the following error to have high accel and high speed. Of course you will have high following error at max speed.

Mike

[peter81]

ok thanks. I will try your settings and let you know what happens .

[vitalsystem]

hi Peter,

I just emailed a new firmware that implements IIR filter (low pass) for more smooth DAC output.  I tested here on my desktop mill and on the scope the output is very clean with no sudden (square wave) changes.

regards,
Rufi

[peter81]

Hi TOTALLYRC,

I've tried the settings you posted. With scale of 100 the machine shakes real hard and trip follow error an also get error in the servo driver ( Over Current). Then I've tried with scale of 1000 with the same pid setting and get better motion.

[TOTALLYRC]

Hi Peter,
Every machine is different,
The settings I gave you are a starting point. Since your are getting good motion with the scale set at 1000, tune from there.

What count encoders are you using?

Mike

[peter81]

I'm using 750W servo motors and 2500 quadrature encoders for X,Y and Z axis. So one revolution of the motor is 10.000 counts. I'm using planetary gearboxes with 10:1 reduction. This means one revolution of the pinion is 100.000 counts. One revolution of the pinion moves gantry 133,33mm.

[TOTALLYRC]

That should give pretty good resolution.

The only possible problem would be if you run up against the max encoder count rate of the DSPMC. It is 2 MHz for the V1 and 4 MHz if IIRC for V2.

[peter81]

Is there any way to calculate this value?