Control Measures For Drives Iinvolving Friction - Parker Compax3 Series Operating Instructions Manual

Parker EME
Note:
Current jerk response with the activated saturation characteristic line
2) (2Aeff)
1)
The paramterization of the characteristic line is made in the MotorManager.
In order to accept the changes in the MotorManager in the project, the ent-
ire configuration must be confirmed.
In order to make the changes from the MotorManager effective in the device, the
configuration download must be executed.

Control measures for drives iinvolving friction

In this chapter you can read about:
Deadband following error................................................................................................. 225
Friction compensation...................................................................................................... 226
Some drives, which involve much friction due to their guiding system, may show
permanent oscillation at standstill. The transition between static friction (standstill)
and kinetic friction (very low speed) is very steep. The controller can not longer
follow the friction characteristic line at this position. The I-term integrates until the
control variable pulls free the drive and the drive moves too far. This procedure is
repeated in the opposite direction and a control oscillation occurs (so-called limit
cycle). In order to eliminate this control oscillation, the following control functions
were implemented:
Deadband following error (Obj. 2200.20)
Filter following error (Obj. 2200.24)
Friction compensation (Obj. 2200.20)
Deadband following error
Deadband/filter following error in the position loop
2200.24 Filter - Tracking Error
T1
-
The deadband does no longer supply a velocity setpoint value (zero) for the subor-
dinate velocity loop at small following error. The integrator of the velocity loop stops
integrating and the system comes to a standstill.
In order to prevent that the velocity loop is excited by the noise on the following
error, the following error should be filtered before the deadband, which will lead,
however, to delays in the position loop. The deadband to be set depends on the
192-120114 N5 C3I22T11 June 2008
2010.1 Velocity feed-forward
K
Vv
2200.20 Deadband –
Tracking Error
K
Px
680.6 Position Tracking error
680.5 Actual Position
Setting up Compax3
225