МЕЖДУНАРОДНАЯ НАУЧНО-ТЕХНИЧЕСКАЯ КОНФЕРЕНЦИЯ
АКТУАЛЬНЫЕ ПРОБЛЕМЫ ЦИФРОВИЗАЦИИ ЭЛЕКТРОМЕХАНИЧЕСКИХ И
ЭЛЕКТРОТЕХНОЛОГИЧЕСКИХ СИСТЕМ
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where
c
– constant,
y
0
– the value of the output signal at the time when
| |
became
less than
с.
A feature of the backlash characteristic is a hysteresis type loop, which has a
constant width 2
с
and length, which varies depending on the amplitude of the input value.
It must be taken into account that during the ―selection‖ of the backlash (
y=y
0
), the driven
element of the mechanical transmission is disconnected from the driving element and,
therefore, the static and dynamic loads on the driving element are reduced. While
selecting the backlash, the hard feedback signal remains constant, and during this time the
system seems to open.
A simple geometric model of backlash (1) corresponds to a mechanical transmission in
which the load has low inertia and an insignificant moment of dry Coulomb friction. In
many cases, such idealization is impossible, and in calculations it is necessary to use a
more complex model taking into account dry friction forces.
In the theory of automatic control, it is customary to distinguish the following
components of the friction moment.
Linear friction, where the friction torque depends linearly on the speed
V=px
. In this case,
linear friction is taken into account as a damping moment and does not violate the
linearity of the transfer function
px
k
M
fr
,
(2)
where
k
– constant coefficient.
Dry or Coulomb friction is a nonlinear component of the friction torque
.
sign
