XPS-Q8 Controller Motion Tutorial
14.1.2.1 PID Corrector Architecture
The PID corrector uses the following error (SetpointPosition – EncoderPosition) as its
input and applies the sum of three correction terms (Kp, Kd and Ki) to determine the
output.
Figure 52: PID Corrector Architecture.
14.1.2.2 Proportional Term
The Kp, or proportional gain, multiplies the current following error of that servo cycle
by the proportional gain value (Kp). The effect is to react immediately to the following
error and attempt to correct it. Changes in position generally occur during commanded
acceleration, deceleration, and in moves where velocity changes occur in the system
dynamics during motion. As Kp is increased, the PID corrector will respond with a
increased output and the error is more quickly corrected. For instance, if a positioner or
group of positioners is expected to have small following errors, as is the case for small
moves where overcoming static friction of the system is predominant, then the Kp may
need to be increased to produce sufficient output to the driver. For larger moves, the
following errors are generally larger and require lower Kp values to produce the desired
output. Also note that for larger moves the kinetic friction of the system is generally
XPSDocumentation V1.4.x (EDH0301En1060 — 10/17) 174
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