Siemens SINUMERIK 840D sl Function Manual page 411

5.6 Friction compensation (quadrant error compensation)
5.6.1 General information
Function
Friction occurs predominantly in the gearing and guideways. Static friction is especially
noticeable in the machine axes. Because it takes a greater force to initiate a movement
(breakaway) than to continue it, a greater following error occurs at the beginning of a
movement.
The same phenomenon occurs on a change of direction where static friction causes a jump
in frictional force. If, for example, one axis is accelerated from a negative to a positive
velocity, it sticks for a short time as the velocity passes through zero because of the
changing friction conditions. With interpolating axes, changing friction conditions can cause
contour errors.
Quadrant errors
This behavior is particularly apparent on circular contours on which one axis is moving at
maximum path velocity and the other is stationary at quadrant transitions. With the aid of
friction compensation these so-called "quadrant errors" can be almost completely eliminated.
General procedure
Measurements on machines have shown that contour errors caused by static friction can be
effectively compensated by the injection of an additional setpoint pulse with the correct sign
and amplitude.
Extended Functions
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Friction compensation (quadrant error compensation)
Compensations (K3)
411