July 2013 6.4 Axis-error compensation 661
6.4.5 Compensation of reversal spikes during circular traverse
With the iTNC 530 HSCI you compensate the reversal spikes through a friction
compensation in the area of the speed controller (MP2610.x to MP2620.x).
“Compensation of sliding friction (only for digital axes)" on page 662.
6.4.6 Compensation of stick-slip friction
On guideways with high stick-slip friction (static friction), a following error can
occur at low feed rates during operation with velocity feedforward control.
This error can be compensated by the iTNC. You can measure following error
by using, for example, the integrated oscilloscope of the iTNC.
With the iTNC 530 HSCI you compensate the reversal spikes with the
machine parameters MP2610.x to MP2620.x. “Stick-slip friction
compensation at quadrant transitions" on page 1106.
Limiting the
integral factor
In machines with very high static friction, a position deviation at standstill can
lead to the accumulation of a very high integral factor. This can lead to a jump
in the position value when the axis "tears loose." In such cases you can limit
the integral-action component of the speed controller with MP2512.x.
The limitation is effective as soon as the axis is in position (W1026/W1104). If
high utilization occurs when an axis is at standstill (e.g. due to static friction),
the current is also limited.
MP2512.x Limit of integral factor of the speed controller
Input: 0.000 to 30.000 [s] (realistically: 0.1 to 2.0)
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