OnRobot VGC10, User Manual

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Operation
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P gain F and P gain T : The proportional term produces a correction that is proportional to the current
error value. Increasing this parameter, has the following effects: faster reaction, overreaction, lower error,
stability degradation.
I gain F and I gain T : The integral term produces a correction that is proportional to both, the magnitude,
and duration of the past error values. Increasing this parameter, has the following effects: faster reaction,
overreaction, lower error, stability degradation.
D gain F and D gain T : The derivative term produces a correction that is proportional to the slope or
changing speed of past error values. Increasing this parameter, has the following effects: less
overreaction, stability increase.
If the force control is too slow, that is, the tool occasionally leaves the surface instead of continually
touching it, try increasing the
P gain F, P gain T, I gain F and I gain T values.
If the force control is overreacting to changes, that is, the tool bounces off the surface, try decreasing the
P gain F and P gain T (or D gain F and D gain T , if it is above 1).
If the force control is reacting to changes too slowly, that is it keeps pushing the surface hard after
touching it, try decreasing the I Gain.
As a rule of thumb, it is recommended to use values:
P Gain < 5
I Gain < 0.25
D Gain < 1
The ratio of P Gain/I Gain = 10
Values that can be used as a base for tuning are:
P Gain F =1, I Gain F = 0.1, D Gain F = 0.3
P Gain T =0.2, I Gain T = 0, D Gain T = 0