# US 10,691,099 B2 · Motor selection apparatus

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- Number: US 10,691,099 B2
- Document ID: US10691099B2
- Status: Granted
- Kind: B2
- Application number: 15/915,523
- Filed: 2018-03-08
- Published: 2018-09-20
- Granted: 2020-06-23
- Earliest claimed: 2017-03-14
- Assignees: Fanuc Corporation
- Applicants: Fanuc Corporation
- Inventors: Yasuo Yamada
- Web page: https://patentgrep.com/patent/US10691099B2

## CPC

- G05B 19/404: characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia (G05B19/19, G05B19/41 take precedence)
- B23Q 3/18: for positioning only
- G05B 2219/35124: Calculate center of gravity of object
- G05B 2219/39188: Torque compensation
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)
- B23Q: DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING (tools of the kind used in lathes or boring machines B23B27/00); MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT

## Abstract

A motor selection apparatus includes: a mechanical condition obtainment unit that obtains information pertaining to a distance between a center of mass of a workpiece and a rotation center of a motor; an operating pattern obtainment unit that obtains information pertaining to an operating pattern; a motor information obtainment unit that obtains information pertaining to instantaneous torque; an eccentric load torque calculation unit that calculates eccentric load torque, which is load torque acting on the motor in accordance with the rotation phase of the motor; an acceleration/deceleration torque calculation unit that calculates acceleration/deceleration torque; a required torque calculation unit that calculates a required torque from a sum of the eccentric load torque and the acceleration/deceleration torque; and a motor selection unit that determines whether a motor can be selected, based on whether the required torque is less than or equal to the instantaneous torque of the motor.

## Claims

### Claim 1

A motor selection apparatus comprising:
a processor to:
obtain information pertaining to a distance between a center of mass of a workpiece and a rotation center of a motor, the motor driving a machine;
obtain information pertaining to an operating pattern executed on the workpiece by the machine;
obtain information pertaining to instantaneous torque, the instantaneous torque being a maximum torque that can be permitted by the motor;
calculate eccentric load torque, the eccentric load torque being load torque acting on the motor in accordance with a rotation phase of the motor while the operating pattern is being executed, in the case where the center of mass of the workpiece is eccentric relative to the rotation center of the motor and a rotation axis is not parallel to the vertical direction;
calculate acceleration/deceleration torque arising when the motor accelerates or decelerates during the execution of the operating pattern;
calculate a required torque from a sum of the eccentric load torque and the acceleration/deceleration torque arising during the execution of the operating pattern; and
select the motor to drive the machine when the required torque is determined to be less than or equal to the instantaneous torque of the motor in all velocity regions in which the workpiece operates according to the operating pattern during the execution of the operating pattern,
wherein the processor finds the eccentric load torque Tel(θ) at a given phase from two different sets of phases (θ1, θ2) and eccentric load torques (T1, T2) by the following equation:
T
el
⁡
(
θ
)
=
|
T
el
′
⁢
sin
⁡
(
θ
-
θ
el
⁢
⁢
0
)
|
θ
el
⁢
⁢
0
=
tan
-
1
⁡
(
-
T
1
·
sin
⁢
⁢
θ
2
+
T
2
·
sin
⁢
⁢
θ
1
-
T
1
·
cos
⁢
⁢
θ
2
+
T
2
·
cos
⁢
⁢
θ
1
)
T
el
′
=
T
1
sin
⁡
(
θ
1
-
θ
el
⁢
⁢
0
)
=
T
2
sin
⁡
(
θ
2
-
θ
el
⁢
⁢
0
)
where, sin(θ1−θel0)=0 or sin(θ2−θel0), Tel′(θ)=0,
θel0: a phase at which the eccentric load torque is 0,
θ1, θ2: given phases,
T1: the eccentric load torque at a phase θ1,
T2: the eccentric load torque at a phase θ2.

### Claim 2 (depends on 1)

The motor selection apparatus of claim 1, wherein the processor further:
finds a friction torque by multiplying a distance between a friction surface and the rotation center of the motor by a friction force, and
calculates the required torque by adding the friction torque to the eccentric load torque.

### Claim 3 (depends on 2)

The motor selection apparatus of claim 2, wherein the processor further:
uses information of a motor used in a similar machine to find a polynomial approximation of a friction torque function, and calculates a friction coefficient from the friction torque function; and
calculates the friction torque for a machine being considered from the friction coefficient, and calculates the required torque by adding the friction torque to the eccentric load torque of the machine being considered.