Newport ESP300 Series - Table 6.1: Servo Parameter Functions

Parameter Function Value Set Too Low Value Set Too High
Determines
stiffness of servo
loop
Servo loop too soft
with high following
errors
Servo loop too tight
and/or causing
oscillation
Kd
Main damping
factor, used to
eliminate
oscillation
Uncompensated
oscillation caused
by other parameters
being high
Ki
Reduces following
error during long
motions and at stop
Oscillations at lower
frequency and higher
amplitude
Vff
Negative following
error during the
constant velocity
phase of a motion.
Stage lags the
desired trajectory
Positive following
error during the
constant velocity
phase of a motion.
Stage is ahead of the
desired trajectory
Kp
Higher-frequency
oscillation and/or
audible noise in the
motor caused by large
ripple in the motor
voltage
Stage does not reach
or stay at the desired
stop position
Reduces following
error during the
constant velocity
phase of a motion
Aff
Reduces following
error during the
acceleration and
deceleration phases
of a motion
Negative following
error during the
acceleration phase
of a motion. Stage
lags the desired
trajectory
Position following
error during the
acceleration phase of
a motion. Stage is
ahead of the desired
trajectory
Table 6.1: Servo Parameter Functions
Section 6 – Servo Tuning 6-5