Position controller gain

Gain

The CNC position controller uses a P controller for position control. The controller gain is defined by the parameter getriebe[x].kv of dimension 0.01/s.

In a stationary case, the following applies when a control loop is set correctly:

Where

   s: position lag

   v: axis velocity

   kv: position controller gain

To set a position controller gain of 3/s, the following entry is required in the axis parameter list:

getriebe[ ].kv       300

Variable name

Type

permitted range

Dimension

kv

UNS32 at the MC_ReadAxisError function block at its AxisErrorID output

0 < kv→ MAX(UNS32)

0.01/s

Adapt the manipulated variable to D/A converter format

The two entries P-AXIS-00129 (getriebe[x].multi_gain_z) and P-AXIS-00128 (getriebe[x].multi_gain_n) are used to adapt the manipulated variable calculated from the position lag to the D/A converter format.

The fraction P-AXIS-00129 / P-AXIS-00128 results in the conversion factor of the manipulated variable into the D/A converter format and is also referred to as the multi-gain factor.

There are 2 possibilities to calculate P-AXIS-00129 and P-AXIS-00128:

1. Arithmetical calculation:

Specify the digital value at the D/A converter input at which the axis moves at a velocity of [1m/min] or [1000 °/min]. To calculate multi_gain_z/multi_gain_n arithmetically, gear ratios, spindle pitch and the scaling factors acting on the velocity command value on the drive side must be known.

2. Experimental determination:

Derived from position lag and axis velocity.

Attention

attention

The entries P-AXIS-00129 and P-AXIS-00128 are provided solely to adapt the format of the manipulated variable. To optimise the control loop, use the position controller gain factor P-AXIS-00099 (getriebe[].kv).