MTS Series 793 - Manual (Page 23)

About Tuning
MTS Series 793 Tuning and Calibration Introduction 23
Proportional (P) Gain
Proportional gain is the primary and coarsest control of the system. It is similar to
a radio’s volume control in that it amplifies the error signal by an appropriate
amount to control the system. In its most generic sense, the term proportional
gain means that the change in power output is proportional to the error.
Remember that for our car, the amount of steering (amplitude) is proportional to
how much we want to correct, and how fast. This is proportional gain. Our
formula is now:
Error = Gain x (Command - Feedback)
Note Proportional gain is not speed (how far your push down on the gas
pedal), it is how fast you turn the steering wheel. So proportional gain in
the servo loop is acceleration. The “speed” of the system is controlled by
the size of the hydraulic components.
Proportional gain looks at the Error
side of the summing junction.
This waveform shows an
unstable (high gain)
feedback signal. This waveform shows a
sluggish (low gain)
feedback signal. The shaded square wave
represents the test
command. The solid
waveform shows an
idealized feedback signal.
Feedback
Command Error