Control device, electric power steering device, and control method

Patent metadata

Field	Value
Publication number	US-2023202554-A1
Application number	US-202218086285-A
Country	US
Kind code	A1
Filing date	Dec 21, 2022
Priority date	Dec 28, 2021
Publication date	Jun 29, 2023
Grant date	—

Abstract

A control device that controls a control target including at least a motor in a steering mechanism including an input shaft to which a steering wheel is connected, an output shaft connected to the input shaft via a torsion bar, and the motor connected to the output shaft. The control device includes a reaction force controller to generate an input torque input to the control target based on a torsion bar torque generated in the torsion bar and to control a reaction force transmitted from the steering wheel to the steering person, and an assist controller to generate a correction torque to correct the input torque based on an output of the control target and a nominal model. The assist controller is configured or programmed such that a transfer function of the control target is constrained by a transfer function of the nominal model in a frequency band.

First claim

What is claimed is:

1 . A control device that controls a control target including at least a motor in a steering mechanism including an input shaft to which a steering wheel steered by a steering person is connected, an output shaft connected to the input shaft via a torsion bar, and the motor connected to the output shaft, the control device comprising:
a reaction force controller to generate an input torque input to the control target based on a torsion bar torque generated in the torsion bar and to control a reaction force transmitted from the steering wheel to the steering person; and an assist controller to generate a correction torque to correct the input torque based on an output of the control target and a nominal model; wherein the assist controller is configured or programmed such that a transfer function of the control target is constrained by a transfer function of the nominal model in a frequency band where a gain in a gain characteristic of a complementary sensitivity function with respect to a modeling error between the control target and the nominal model is approximately 1; and the nominal model is a model in which mechanical characteristics when the steering person steers the steering wheel are considered.

2 . The control device according to claim 1 , wherein an order of the transfer function of the nominal model is 3 or more.

3 . A control device that controls a control target including at least a motor in a steering mechanism including an input shaft to which a steering wheel steered by a steering person is connected, an output shaft connected to the input shaft via a torsion bar, and the motor connected to the output shaft, the control device comprising:
a reaction force controller to generate an input torque input to the control target based on a torsion bar torque generated in the torsion bar and to control a reaction force transmitted from the steering wheel to the steering person; and an assist controller to generate a correction torque to correct the input torque based on an output of the control target and a nominal model; wherein the assist controller is configured or programmed such that a transfer function of the control target is constrained by a transfer function of the nominal model in a frequency band where a gain in a gain characteristic of a complementary sensitivity function with respect to a modeling error between the control target and the nominal model is approximately 1; and an order of the transfer function of the nominal model is 3 or more.

4 . The control device according to claim 1 , wherein the nominal model is a model having a frequency characteristic between a one-inertia system and a two-inertia system.

5 . A control device that controls a control target including at least a motor in a steering mechanism including an input shaft to which a steering wheel steered by a steering person is connected, an output shaft connected to the input shaft via a torsion bar, and the motor connected to the output shaft, the control device comprising:
a reaction force controller to generate an input torque input to the control target based on a torsion bar torque generated in the torsion bar and to control a reaction force transmitted from the steering wheel to the steering person; and an assist controller to generate a correction torque to correct the input torque based on an output of the control target and a nominal model; wherein the assist controller is configured or programmed such that a transfer function of the control target is constrained by a transfer function of the nominal model in a frequency band where a gain in a gain characteristic of a complementary sensitivity function with respect to a modeling error between the control target and the nominal model is approximately 1; and the nominal model is a model having a frequency characteristic between a one-inertia system and a two-inertia system.

6 . The control device according to claim 1 , wherein
the assist controller includes:
a high-pass filter having a first cutoff frequency; and
a low-pass filter having a second cutoff frequency higher than the first cutoff frequency; and
when a transfer function of the low-pass filter is Q(s) and a transfer function of the high-pass filter is HPF(s), the complementary sensitivity function is Q(s)·HPF(s).

7 . The control device according to claim 1 , wherein an expression representing the transfer function of the nominal model is an expression obtained by adding an attenuation term to an expression representing a two-inertia system.

8 . The control device according to claim 7 , wherein a transfer function P n (s) of the nominal model is expressed by a following Expression:

P
n

(
s
)

=

1

J

STG
n

⁢
s

+

B

STG
n

⁢

s
2

+

2
⁢

ζ

1
⁢
n

⁢

ω

1
⁢
n

⁢
s

+

ω

1
⁢
n

2

s
2

+

2
⁢

ζ

2
⁢
n

⁢

ω

2
⁢
n

⁢
s

+

ω

2
⁢
n

2

 where s is a Laplace transformer, J STGn is a parameter representing inertia moment of the nominal

Assignees

• Nidec Corp

Inventors

• Endo Shuji
• Miyake Sohei
• Ishikawa Masaya
• Notsu Daisuke

Classifications

• B62D5/0463 Primary

  calculating assisting torque from the motor based on driver input · CPC title

• H02P23/0022

  Model reference adaptation, e.g. MRAS or MRAC, useful for control or parameter estimation · CPC title

• B62D5/0421

  Electric motor acting on or near steering gear · CPC title

• H02P6/04

  Arrangements for controlling or regulating the speed or torque of more than one motor (H02P6/10 takes precedence) · CPC title

• H02P6/34

  Modelling or simulation for control purposes · CPC title