Friction Compensation Overview - Siemens SINUMERIK 840D sl Function Manual

Check contour monitoring
As the two equivalent time constants:
● MD32810 $MA_EQUIV_SPEEDCTRL_TIME (equivalent time constant speed control loop
for feedforward control)
and
● MD32800 $MA_EQUIV_CURRCTRL_TIME) (equivalent time constant current control loop
for feedforward control)
also influence the contour monitoring, this should be subsequently checked.
References:
Function Manual, Basic Functions; Axis Monitoring, Protection Zones (A3)
Influence on the servo gain factor (K
When the feedforward control is set correctly, the response to setpoint changes in the
controlled system under speed feedforward control is as dynamic as that of the speed control
loop or, under torque feedforward control, as that of the current control loop, i.e. the servo gain
factor (K
control behavior (e.g. corner errors, overshoots, circle/radius errors).
On the other hand, feedforward control does not affect the response to disturbances
(synchronism). In this case, the servo gain factor (K
factor.
Service display "K factor"
V
When a feedforward control is active, the servo gain (K
servo gain factor (K
display "axis/spindle" is very high.
5.6

Friction compensation overview

In addition to the mass inertia and the machining forces, the friction forces in the gearing and
guideways of the machine influence the dynamic behavior of a machine axis. In particular,
when accelerating a machine axis from standstill, the transition from static to sliding friction
has an adverse effect. The resulting sudden change in the friction force results in a briefly
increased following error. With interpolating axes, this results in significant contour violations.
For circles, these occur especially at the quadrant transitions where one of the participating
axes is stationary as its direction is reversed.
To improve the contour accuracy at these points, an additional setpoint pulse (velocity or torque
setpoint pulse) is applied to the friction compensation when a machine axis is accelerated from
standstill.
Extended Functions
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
factor)
V
factor) entered into MD32200 $MA_POS_CTRLGAIN hardly has any effect on the
V
factor) active as response to setpoint changes) shown in the service
V
K3: Compensations
5.6 Friction compensation overview
factor) entered in MD32200 is the active
V
factor) of the axis (corresponds to
V
321