Lite-On Technology Corp.
Industrial Automation
80
5.5.4.
Manual adjustment of gain parameters
In addition to the automatic/semi-auto adjustment mode, the user can enter the control gains for the position
and speed loops manually.
Generally, precise machining needs higher rigidity and response frequency, but higher response frequency
may cause mechanical resonance easily.
Therefore, the gain must be increased gradually during the tuning process and trial run must be conducted.
Reduce the gain value when resonance is generated.
The tuning principles in terms of the gain are described below:
The proportion gain for position control (KPP,PB-20)
The KPP parameter determines the characteristic of the position loop response. The higher the
numerical value, the faster the position loop response, the lower the command following and tuning
errors, and the shorter the tuning duration. However, when the value is set to high, the machine may
jitter or overshoot may occur.
The calculation method of the position loop response frequency is described below:
Position loop response frequency (Hz)
＝
𝐾𝑃𝑃
2𝜋
Position feed-forward gain(PFG, PB-22)
Position feed-forward gain can increase the response when the command changes and reduce the
command following error and the tuning duration.
However, overshoot or vibration may occur if the setting value is too high.
The proportion gain for speed control (KVP, PB-24)
The KVP parameter determines the feature of the speed loop response. The higher the value, the faster
the response and the lower the command following error. However, mechanical resonance if the value
is set too high. The speed loop response frequency must be 4~6times the position loop response
frequency. The machine may jitter or overshoot may occur if both frequencies are too close.
The calculation method of the position loop response frequency is described below:
Position loop response frequency (Hz)
＝
𝐾𝑉𝑃
2𝜋
The proportion gain for speed control (KVI, PB-26)
Higher KVI is better at removing the speed steady-state error, but the machine may jigger if the value is
set to high.
The suggested setting is:
KVI
≤
1
.
5
×
speed loop response frequency
