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6250 Servo Controller User Guide

d. In the Data Acquisition display, select the Start button to trigger the move and

gather data.

e. Note the plot in the Graph Display; the actual position (or velocity) probably lags the

commanded position (or velocity).

The objective is to increase SGVF until the lag is reduced to a level suitable for your

application.

Step 7 Use the Acceleration Feedforward Gain (SGAF) to reduce position error during acceleration:

If you are not using Motion Architect:

➀ Execute a continuous (MC1 command) move, setting the acceleration, deceleration and

velocity values appropriate to your application. Set SGAF to 0.01 (SGAFØ.Ø1).

➁ Check the position error during acceleration by issuing the TPER command.

➂ Increase SGAF to reduce the position error (repeat steps ➀ and ➁ as necessary).

a. In the Tuning Gains panel, set the initial value for SGAF to 0.01.

b. In the Data Acquisition display, select the Start button.

c. Note the plot in the Graph Display; the actual position (or velocity) probably lags the

commanded position (or velocity).

The objective is to increase SGAF until the lag is reduced to a level suitable for your

application.

Tuning Scenario

The following tuning scenario presents an actual example of tuning Compumotor 6250 Servo

Controller with a Digiplan UD Drive system with a brushed motor and unknown load inertia.

The UD Drive operates in velocity mode; therefore, the 6250's analog control signal output is a

velocity command to the UD.

This example shows how to obtain the highest possible proportional feedback (SGP) and

velocity feedback (SGV) gains experimentally by using the flow diagram illustrated earlier in

Step 5 of the Tuning Procedure.

NOTE

The steps shown below (steps 1 - 11) represent the major steps of the process; the actual

progression between these steps usually requires several iterations.

The motion command used for this example was a step command with a step size of 100. The

plots shown are as they appeared in Motion Architect's Controller Tuner Module (X axis =

time, Y axis = position).

Step 1

For a starting trial, we set the proportional

feedback gain (SGP) to 2. As you can see by

the plot, the response was slow.

In the next step, we should increase SGP

until the response is slightly underdamped.

SGP = 2

Commanded Position

Actual Position

1 2 ... 42 43 44 45 46 47 48 49 50 51 52 ... 137 138

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Calculated Industries 6250 Guide de l'utilisateur Page 47