Rockwell-automation 1771-QB Linear Pos. Manuel d'utilisateur télécharger pdf (Page 131)

Initializing and Tuning the Axes

Chapter 8

813

5. Set the integral gain equal to 70% of the proportional gain at which

continuous oscillations occurred (see step 3).

= 0.7 x K

6. Set the derivative gain equal to 70% of the proportional gain at which

continuous oscillations occurred (see step 3). This small derivative gain is

recommended to improve axis stability.

= 0.7 x K

7. Check the axis stability under all load conditions. In some instances, you

may have to adjust the proportional, integral and derivative gains slightly

or use the gain reduction factor to obtain the desired results.

Example: Optimal PID Loop Gain Calculation

If continuous oscillations occur with a proportional gain of 0.1000 ips/mil and

the integral and derivative gains set to zero, the optimal gains are calculated as

follows:

P(unstable)

= 0.1000 ips/mil

= 0.7 x 0.1000 = 0.0700 ips/ mil

= 0.7 x 0.0700 = 0.0490 (ips/s)/mil

= 0.7 x 0.0700 = 0.0490 unitless

Update the Application Program

As a final step, you should copy the parameter block data determined above,

into the data tables for your application. The tuning and integration procedure

used axis 1, but you can perform a similar procedure with axis 2.

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Rockwell-automation 1771-QB Linear Pos. Manuel d'utilisateur Page 131