E x a m p l e 1. Control system of a hydraulic drive on the basis of typical linear links of ACS. On Fig. 2 the hydraulic drive circuit with a control system described by a set of typical linear links of automatic control is presented.
Fig. 2. Control system of a hydraulic drive on the basis of typical linear links of ACS
Object of control – hydraulic system
The electro hydraulic amplifier
E x a m p l e 2. Simulation of a control system by a hydraulic drive. Let's consider a problem of simulation of dynamics of a hydraulic drive of the testing stand with an electro mechanical control system (Fig. 3).
Fig. 3. The circuit diagram of a hydraulic drive of the testing stand with an electro mechanical control system
The hydraulic drive of the stand consists of the hydraulic cylinder (7–8–14), moving the lever mechanism (14-23) with cargo in a mass
where
and the entrance signal generator as function of movement of the hydraulic cylinder piston relatively the average position described by the following nonlinear function:
where rectangular impulse (see Fig. 4). Thus, the system consists of 29 elements connected in 36 nodes, and is described by the 40-th order system of algebraic-differential equations. Basic parameters of hydraulic system:
diameter of conditional passage 20 mm, a spool stroke 1.8 mm, flow coefficient of spool channels 0.62; geometric characteristics of spool channels, expressing dependence of sectional areas of channels on spool position
z
, is presented on Fig. 3
c
.
^{
3
}
, kinetic viscosity 2
^{
.
}
10
^{
-5
}
m
^{
2
}
/s, the volumetric elasticity module 1765 MPa;
m
= 19600 kg, rigidity
c
= 6.86
^{
.
}
10
^{
6
}
N/m, coefficient of viscous friction
h
= 0.
Force on the rod
x
–
_{
14
}
x
)
. Dependence of the flow
_{
23
}
Q
_{
1
}
in node 1 (Fig. 3
b
) considers the static characteristic of pressure relief valve not shown on the circuit diagram. Coefficients of equations of dynamic links are specified Fig. 3
а
.
Transient processes in a hydraulic drive of the testing stand, received as a result of mathematical simulation, are presented on Fig. 4.
Fig. 4. Dynamics of a hydraulic drive of the testing stand with an electro mechanical control system Similar calculations and researches executed on a design stage, allow to find an optimum variant of a control system for concrete object of control, for example, for a hydraulic drive. |

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