Consider now transient
response of the servomechanism to a ramp input (Fig.1.4b). In the early stages
of the input (instant 
), and while the error
signal is small, the load accelerates slowly and lags behind the input. The
signal increases as the lag increases, thereby building up the acceleration.
Eventually the input and loud speeds are equal (instant 
),
but since a substantial position error exists, the load continuous to
accelerate. Then the acceleration is reduced, and the load attains a constant
speed (instant 
) at zero position error
with no error signal, and so on. Thus, as in the case of a step input, a
continuous oscillation is produced.
If there are coloumb and viscous frictions the oscillations are damping (Fig.1.4). But using only inherent friction light damping is achieved. It is necessary, therefore, to use special approaches to restrict the oscillations.
The actuator is intended for activity in a structure of the servomechanism as an actuator of the autopilot and mechanically connected to a control system of an airplane.
The main characteristics:
Voltage
across the winding of excitation of the engine 
Voltage
across the winding of control of the engine 
The
firing moment of the engine 
Voltage
across the winding of excitation of a tachogenerator 
Steepness
of voltage output of a tachogenerator not less 
Steepness
of voltage output of the induction potentiometer not less 
Power
of engine DG – 25B 
Efficiency
of the reduction gearbox 
The given block diagrams of linear and non-linear servomechanisms we find in mathematical packet MATLAB 6.1 as follows:
1. We start MATLAB;
2. In a command line we write Demos;
3. In menu MATLAB Demos Simulink it is chosen Aerospace in which menu it is chosen Electrohydraulic Servomechanisms;
4. We receive schemes of linear and non-linear servomechanisms;
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Nonlinearservomechanism
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Definition of transients of servomechanism
Drawing of transient characteristics (of linear servomechanism) is made under following scheme
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Linear Nonlinear
From the received schedules it is visible, that the system is steady.
Settling time 
Overshoot 
Research of frequency response of servomechanisms
Research of frequency response we shall conduct on linear model.
To draw frequency characteristics it is necessary to receive a transfer function of a servomechanism.
Transfer function of closed-loop system is
where 
-
transfer function of disconnected system
proceeding from this
The logarithmic amplitude frequent characteristic,
The logarithmic phase frequent characteristic,
The amplitude-phase frequent characteristic,
Drawing LAFC, LPFC , MPFC with the help of commands Bode, Nyquist.
From the received schedules it is visible, that the system is absolutely steady.
The principal diagram of the final cascade of the servomechanism amplifier
Fig. 2.1. The final cascade of the amplifier
It is
necessary to choose transistors 
for obtaining in load of voltage 
and a current 
.
We choose the
amplifier of general application 
. Its basic parameters:
3. Maximum voltage on a collector
Taking into account values
, we choose transistors 
и 
. Their basic parameters:
These transistors meet the
requirements on permissible 
, transistors 
can be used without heat
rejections.
5. 
6. Power supply voltage
of the amplifier 
7. 
at 
:
transistors 
are open we shall
define a current of base
At 
transistors are open for currents:
, that is the amplifier
provides a current of load
.
10. Maximum voltage 
of transistors:
.
11. Power, which
dissipates on transistors:
.
Taking into account the received values, we choose
transistors 
12. Currents of bases of transistors:
.
13. Currents of dividers 
and 
also should exceed
considerably
. We receive 
.
Whence 
14.
Resistance
of resistors 
it is considered, taking into
account 
:
Means, 
We receive 
15. Capacitor
The analysis standard TP and selection of operations
Analyzing standard TP, we choose operations for worker TP [11].
table
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