OnRobot HEX-E QC - Page 69

The PID force/torque controller continuously calculates the error value for the force/torque
measured by the sensor, compared to the values set by the F/T Control command, and
applies correction based on this error.
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
eects: 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
eects: 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
eects: 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
o 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
F/T Move
The F/T Move command can be used together with the F/T Waypoint, to move the robot
along a route, or together with the F/T Path to move the robot along a path and stop once
the
defined force/torque limits are reached (movement interrupted). In this case a warning can
be generated. If the movement reaches the last waypoint, the move is successful.
NOTE:
To cancel any force/torque oset, execute an F/T Zero command at the
beginning of the F/T Move command and make sure the tool is not in contact
with any object before starting the F/T Move, otherwise the command may not
stop at the given force/torque limit.
OPERATION
69