ELECTRIC POWER STEERING DEVICE

• US 20150251691A1
• Filed: 02/27/2015
• Published: 09/10/2015
• Est. Priority Date: 03/07/2014
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: TAMAIZUMI, Terutaka, EKI, Hirozumi, KITA, Masayuki, NAMIKAWA, Isao, NISHIMURA, Akihiko, HASEGAWA, Jun
• Granted Patent: US 9,573,616 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B62D 5/0412 the axes of motor and steering column being parallel
• CPC Class Codes: B62D 5/0472 for damping vibrations
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

A control device in an electric power steering device calculates a first assist component based on steering torque and a vehicle speed. The control device also calculates a compensation component associated with an reverse input and calculates a steered angle command value based on an addition value of the compensation component and basic drive torque that is an addition value of the steering torque and the first assist component, produces a second assist component by performing steered angle feedback control that causes the steered angle of a vehicle to follow the steered angle command value. The control device controls drive of a motor based on an assist command value that is an addition value of the first assist component and the second assist component.

Claims

1. An electric power steering device comprising:

an assist mechanism that applies assist force from a motor to a steering mechanism of a vehicle; and

a control unit that controls drive of the motor based on an assist command value associated with a target value for the assist force, wherein

the control unit includes;

a basic assist component calculation unit that calculates a first assist component serving as a basic component for the assist force based on steering torque applied by the steering mechanism in response to steering operation of the vehicle;

a compensation component calculation unit that calculates a compensation component associated with a reverse input acting on the steering mechanism from steered wheels of the vehicle; and

an assist command value calculation unit that calculates the assist command value by compensating the first assist component based on the compensation component, wherein

the compensation component calculation unit includes;

a reverse input detection unit that detects or estimates the reverse input;

a filter unit that extracts a specific frequency component belonging to a certain frequency band from the detected or estimated reverse input; and

a phase adjustment unit that adjusts the phase of the specific frequency component extracted by the filter unit, wherein

the compensation component calculation unit calculates the compensation component based on the phase-adjusted specific frequency component.

3. The electric power steering device according to claim 1, wherein

the certain frequency band is a frequency band associated with a first reverse input component included in the reverse input and reflecting a road condition, and

the phase adjustment unit is configured to adjust the phase of the specific frequency component such that the degree of a phase shift between the first reverse input component in the steering mechanism and the assist force associated with the compensation component is 0°

.

4. The electric power steering device according to claim 1, wherein

the certain frequency band is a frequency band associated with a second reverse component included in the reverse input and causing poor steering feel, and

the phase adjustment unit is configured to adjust the phase of the specific frequency component such that the degree of a phase shift between the second reverse input component in the steering mechanism and the assist force associated with the compensation component is 180°

.

5. The electric power steering device according to claim 1, wherein

the compensation component calculation unit further includes a map calculation unit that calculates the compensation component from the phase-adjusted specific frequency component based on a map indicating a relation between the phase-adjusted specific frequency component and the compensation component.

2. An electric power steering device comprising:

an assist mechanism that applies assist force from a motor to a steering mechanism of a vehicle; and

a control unit that controls drive of the motor based on an assist command value associated with a target value for the assist force, wherein

the control unit includes;

a basic assist component calculation unit that calculates a first assist component serving as a basic component for the assist force based on steering torque applied by the steering mechanism in response to steering operation of the vehicle;

a steered angle command value calculation unit that calculates a steered angle command value associated with a target value for a steered angle of steered wheels of the vehicle based on the steering torque;

a steered angle feedback control unit that calculates a second assist component by performing steered angle feedback control that causes the steered angle of the steered wheels to follow the steered angle command value;

a compensation component calculation unit that calculates a compensation component associated with a reverse input acting on the steering mechanism from the steered wheels; and

an assist command value calculation unit that calculates the assist command value based on an addition value of the first assist component and the second assist component, and changes the assist command value based on the compensation component, wherein

the compensation component calculation unit includes;

a reverse input detection unit that detects or estimates the reverse input;

a filter unit that extracts a specific frequency component belonging to a certain frequency band from the detected or estimated reverse input; and

a phase adjustment unit that adjusts the phase of the specific frequency component extracted by the filter unit, wherein

the compensation component calculation unit is configured to calculate the compensation component based on the phase-adjusted specific frequency component.

6. The electric power steering device according to claim 2, wherein

the certain frequency band is a frequency band associated with a first reverse input component included in the reverse input and reflecting a road condition, and

the phase adjustment unit is configured to adjust the phase of the specific frequency component such that the degree of a phase shift between the first reverse input component in the steering mechanism and the assist force associated with the compensation component is 0°

.

7. The electric power steering device according to claim 2, wherein

the certain frequency band is a frequency band associated with a second reverse component included in the reverse input and causing poor steering feel, and

the phase adjustment unit is configured to adjust the phase of the specific frequency component such that the degree of a phase shift between the second reverse input component in the steering mechanism and the assist force associated with the compensation component is 180°

.

8. The electric power steering device according to claim 2, wherein

the compensation component calculation unit further includes a map calculation unit that calculates the compensation component from the phase-adjusted specific frequency component based on a map indicating a relation between the phase-adjusted specific frequency component and the compensation component.