US Patent No. 9,257,932

CONTROL DEVICE FOR SERVOMOTOR


Patent No. 9,257,932
Issue Date February 09, 2016 
Title Control Device For Servomotor
Inventorship Satoshi Ikai, Yamanashi (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,257,932

1. A control device of a servomotor for driving a machine tool, comprising:
a current control loop selecting unit configured to select a first current control loop or a second current control loop having
a response speed slower than that of the first current control loop, as a current control loop to be used in controlling a
current flowing through the servomotor based on an input current command value;

a filter configured to attenuate an input or an output of the first current control loop or the second current control loop
selected by the current control loop selecting unit in accordance with a set attenuation ratio in a specific frequency range;
and

a filter attenuation ratio setting unit configured to set, as the attenuation ratio of the filter, a first attenuation ratio
when the first current control loop is selected by the current control loop selecting unit, and a second attenuation ratio
smaller than the first attenuation ratio when the second current control loop is selected, wherein

a compensator provided in the first current control loop is a PI compensator, and a compensator provided in the second current
control loop is an I-P compensator.