Step 8. Tune The Servo System - Galil Motion Control DMC-1000 User Manual

Table of Contents

Adjusting the tuning parameters is required when using servo motors. The system compensation

provides fast and accurate response and the following presentation suggests a simple and easy way for

compensation . More advanced design methods are available with software design tools from Galil,

such as the Servo Design Kit (SDK software )

The filter has three parameters: the damping, KD; the proportional gain, KP; and the integrator, KI.

The parameters should be selected in this order.

To start, set the integrator to zero with the instruction

KI 0 (CR)

and set the proportional gain to a low value, such as

KP 1 (CR)

KD 100 (CR)

For more damping, you can increase KD (maximum is 4095). Increase gradually and stop after the

motor vibrates. A vibration is noticed by audible sound or by interrogation. If you send the command

TE X (CR)

a few times, and get varying responses, especially with reversing polarity, it indicates system

vibration. When this happens, simply reduce KD.

Next you need to increase the value of KP gradually (maximum allowed is 1023). You can monitor the

improvement in the response with the Tell Error instruction

KP 10 (CR)

TE X (CR)

As the proportional gain is increased, the error decreases.

Again, the system may vibrate if the gain is too high. In this case, reduce KP. Typically, KP should

not be greater than KD/4. (Only when the amplifier is configured in the current mode).

Finally, to select KI, start with zero value and increase it gradually. The integrator eliminates the

position error, resulting in improved accuracy. Therefore, the response to the instruction

TE X (CR)

becomes zero. As KI is increased, its effect is amplified and it may lead to vibrations. If this occurs,

simply reduce KI. Repeat tuning for the Y, Z and W axes.

DMC-1000

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Step A. Install SM jumpers

Each axis of the DMC-1000 that will operate a stepper motor must

have the corresponding stepper motor jumper installed. For a

discussion of SM jumpers, see step 2.

Step B. Connect step and direction signals.

Make connections from controller to motor amplifiers. (These signals

are labeled PULSX and DIRX for the x-axis on the ICM-1100).

Consult the documentation for your step motor amplifier.

Step C. Configure DMC-1000 for motor type using MT command. You

can configure the DMC-1000 for active high or active low pulses. Use

the command MT 2 for active high step motor pulses and MT -2 for

active low step motor pulses. See description of the MT command in

the Command Reference.