МЕЖДУНАРОДНАЯ НАУЧНО-ТЕХНИЧЕСКАЯ КОНФЕРЕНЦИЯ
АКТУАЛЬНЫЕ ПРОБЛЕМЫ ЦИФРОВИЗАЦИИ ЭЛЕКТРОМЕХАНИЧЕСКИХ И
ЭЛЕКТРОТЕХНОЛОГИЧЕСКИХ СИСТЕМ
150
Coulomb friction is characterized by a nonlinear dependence of the resistance
force on speed. Dry friction is characterized by a dependence that is very complex. The
curvilinear part of the characteristic is sometimes replaced
by a straight line with a
negative slope;
nonlinearity of the characteristics of electric motors, which significantly
manifest themselves in the modes of start, reverse, braking, and transition from one state
to another;
nonlinearities due to the nature of the load, for example, the dependence of the
moment of static resistance on the rotation speed (propeller) or on the path (shears for
cutting metal);
functional nonlinearities (for example, nonlinearities such as the product of two
functions);
nonlinearities associated with quantization of signals by level in discrete
control systems, for example, quantization of a signal by time
in a pulse-width control
system;
nonlinearities caused by the properties of the thyristor converter, for example,
the characteristic of a thyristor DC converter.
The nonlinear characteristics discussed above do not exhaust the possible types of
nonlinearities. They are the most typical and often found. When studying specific
dynamic nonlinear EMS, it is advisable to first determine the influence of certain
nonlinearities in order to compile an acceptable model of the system.
Let us consider in more detail the mathematical description
of some of the most typical
analytical nonlinearities. On the basis of this description, analytical nonlinearities of other
types can be described similarly.
Nonlinearity of the type of coordinate restrictions caused by elements of the control
system is analytically described in the following way:
.
if
,
sigh
;
if
,
0
0
0
