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5.5 Positioning controller
VMODE (Selecting the control mode)
Command
VMODE_1
VMODE_2
The fundamental control structure can be changed with this parameter.
SDD:
Stroke-Dependent Deceleration. In this mode, stroke-dependent deceleration is activated. This
mode is the default mode and is suitable for most applications. With stroke-dependent decelera-
tion the drive comes to a controlled stop at the target position. From the set deceleration point the
drive then switches to control mode and moves accurately to the desired position. This control
structure is very robust and reacts insensitively to external influences such as fluctuating pres-
sures. One disadvantage is that the speed varies with the fluctuating pressure as the system runs
under open-loop control.
NC:
Numerically Controlled. In this mode a position profile is generated internally. The system always
works under control and uses the following error to follow the position profile. The magnitude of
the following error is determined by the dynamics and the set control gain. The advantage is that
the speed is constant (regardless of external influences) due to the profile demand. Because of
continuous control, it is necessary not to run at 100% speed, as otherwise the errors cannot be
corrected. 80% of the maximum speed is typical although especially the system behaviour and
the load pressure should be taken into account when specifying the speed.
VRAMP (Ramp time for external speed demand)
Command
VRAMP_1
VRAMP_2
The rate of change of the external speed demand can be limited by this ramp time. In NC mode, this value
should be set to 10ms.
ACCEL (Acceleration in NC mode)
Command
ACCEL_1
ACCEL_2
This command is used to define the acceleration in NC mode. The command is only active if the VMODE
has been parameterized to NC. For stable operation it must be set to a value which is a little smaller than the
technically possible acceleration. Experience shows that a factor of 3...5 should be considered.
Page 29 of 70
Parameters
X
x= SDD|NC
X
Parameters
X
x= 1... 2000
X
Parameters
X
x= 1... 20000
X
POS-124-U
Unit
Group
-
POS_CTRL
Unit
Group
ms
POS_CTRL
Unit
Group
mm/s
POS_CTRL
24.01.2022
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