2-15
What this means is that all error signals will be integrated (or smoothed out). The load will not respond as
quickly. The inertia of the load will be reduced, and the system will be damped.
The capacitor, by not responding instantaneously to the error signal, causes the damping action. This
action is used to stabilize the servo system at the new velocity. By tailoring the stabilization network
(through the proper selection of the RC components) to the system's performance requirements and the
type of load to be driven, undesirable load or performance characteristics can be minimized.
The various compensating networks that you will encounter will depend on the design of the
individual servo system and will be covered in the associated system's technical manual.
In summary, the key to understanding compensating networks is to realize that components are
chosen so the capacitor does not have time to charge and discharge in response to large, rapid
fluctuations.
Q-15. Error-rate damping is effective because the circuitry has the capability of ______________the
amount of overshoot before it happens.
FREQUENCY RESPONSE
The frequency response of a servo is the range of frequencies to which the system is able to respond
in moving the load. It is a characteristic of the system, chosen by the designers so the system will be able
to respond to whatever frequencies are expected to be present in the input signal for the particular
application.
Oscillating Input Signal
At first, we considered the input order to a servo as being suddenly put at a fixed desired value.
Later, we studied the case where the order slowly increased to the desired value. Actually, the input order
to a servo in a given application may accelerate, start, stop, or oscillate about a fixed point. We will now
consider the actions of a servo while the order oscillates. When the order is constant, oscillations of the
load are undesirable. When the order oscillates, the load must oscillate in a similar manner.
Let's assume that an oscillating input signal (order) is applied to a servo. The load may behave in
several ways. Ideally, it would respond in perfect sync with the order. Actually, the amplitude and phase
of the load are different from those of the order, figure 2-10. As we noted above, the frequency response
of the system is normally designed so the load is able to respond to the order.
