US Patent No. 9,071,174

MOTOR CONTROL DEVICE CONTROLLING A PLURALITY OF MOTORS THAT DRIVE ONE DRIVEN BODY


Patent No. 9,071,174
Issue Date June 30, 2015
Title Motor Control Device Controlling A Plurality Of Motors That Drive One Driven Body
Inventorship Junichi Tezuka, Yamanashi (JP)
Hajime Ogawa, Yamanashi (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,071,174

1. A motor control device controlling a plurality of motors that drive one driven body moving along one movement shaft, the
motor control device comprising:
a first physical quantity detecting unit which detects a first physical quantity concerning either the driven body or the
motor when the plurality of motors are in excited states;

an alarm generating unit which generates an alarm for at least one motor among the plurality of motors at a first timing in
accordance with a state of the motor;

a first state switching unit which switches the state of the motor that has caused the alarm, from an excited state to an
un-excited state at the first timing;

a brake commanding unit which outputs, to a brake that brakes the driven body, a command for switching a state of the brake
from a releasing state to a fastening state at a second timing that is a timing when a brake operation completing period of
time set in advance lapses from an alarm generation timing;

a state switch timing setting unit which sets a state switch timing to be either the first timing or the second timing on
the basis of the first physical quantity, wherein the state switch timing is a timing when the state of the motor other than
the motor that has caused the alarm is switched from an excited state to an un-excited state; and

a second state switching unit which switches the state of the motor other than the motor that has caused the alarm, from an
excited state to an un-excited state at the state switch timing, wherein

when the first physical quantity is at least either a magnitude of torque generated by a motor other than the motor that has
caused an alarm during the generation of the alarm, or a moving speed of the driven body moving along the moving shaft during
the generation of the alarm, said state switch timing setting unit sets said state switch timing to said first timing when
said magnitude of torque becomes more than or equal to a first predetermined value or said speed becomes more than or equal
to a second predetermined value, and sets said state switch timing to said second timing when said magnitude of torque becomes
lower than said first predetermined value and said speed becomes lower than said second predetermined value.