Chapter 1 Summary
7
Figure 1-7 Servo dynamic response curve
Rise time t
r
:
It refers to the time elapsed when the rotating speed output rises from zero to 90 percent
of steady state value R (t). It indicates the rapidity of dynamic response.
Adjustment time t
s
:
The range within ±5% of the steady-state value taken near the steady-state
value of the step response curve is considered a permissible error band. The minimum time required
for the response curve to reach but not go beyond the error band is the adjustment time which is used
to measure the rapidity of the complete adjustment process of the unit.
Overshoot
σ
:
It refers to the ratio of the maximum rotating speed difference (Rmax(t)-R (t)) between
rotating speed output and steady-state value to steady-state value R (t). It reflects the relative stability
of a servo unit and is as follows when indicated by percentage:
%
100
)
(
)
(
)
(
(%)
max
×
−
=
t
R
t
R
t
R
σ
Steady-state error:
The difference between the expected steady-state value and actual output of the
system after rotating speed becomes steady during system response.
Servo static performance:
The most important for a servo control system is its stability. The key
static performance index of servo is positioning accuracy, which refers to the degree of deviation of
the actual state from expectation at the end of the system transition. The steady-state accuracy of
servo is subject to the error of position measuring appliance and system error and is related to the
structure and parameters of the system. Figure 1-8 is a position servo static curve graph.
Summary of Contents for DA98E Series
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