# Experimental determination:

Alternatively, the ratio multi_gain_z/multi_gain_n can be determined experimentally. The actual gain acting in the position control loop can be determined from the position lag and axis velocity when the axis is moving at constant speed according to the equation:

The gain determined experimentally is compared with the kv factor (P-AXIS-00099) set in the axis parameter list:

Then the new multi-gain factor is calculated starting from the currently parameterised values of multi_gain_z and multi_gain_n:

After completing a parameter change, the parameters must be checked again using equation 1. To further optimise the position control loop, the parameter P-AXIS-00099 (getriebe[].kv) is used exclusively.

## Attention

If factor f is greater than 1, the total gain in the position control loop increases when the multi_gain factor is changed. This may cause the axes to oscillate. In such cases, set the position controller gain P-AXIS-00099 to the value P-AXIS-00099 / f in order to maintain total gain in the position control loop constant.

## Example

Position lag and gain in the position control loop:

position lag s = 1,9 mm, axis velocity v = 200 mm/min, P-AXIS-00099 = 400 * 1/s, multi_gain_z = multi_gain_n = 1.

Actual gain in the position control loop:

k = v/s = 200 mm / (60 s * 1.9 mm)

k = 1.75

The ratio between parameterised gain and actual effective gain results from equation 1:

The multi-gain factor is therefore.

Possible entries in the axis parameter list would then be:

P-AXIS-00129: getriebe[ ].multi_gain_z 2286

P-AXIS-00128: getriebe[ ].multi_gain_n 1000

Since these entries increase total gain in the position control loop by the factor f, P-AXIS-00099 should also be multiplied by the factor i/f to maintain total gain in the control loop constant:

After checking the parameters calculated based on equation 1, the position control loop can be further adjusted by changing P-AXIS-00099.