Vehicle steering apparatus

• US 8,744,687 B2
• Filed: 06/12/2012
• Issued: 06/03/2014
• Est. Priority Date: 04/02/2007
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: Hayama, Ryouhei, Kada, Tomoyasu, Maeda, Shingo, Kimura, Shuuji
• Primary Examiner(s): Algahaim, Helal A
• Assistant Examiner(s): Darby, Kelly E
• Application Number:
  US13/494,391
• Publication Number:
  US 20120253603A1
• Time in Patent Office: 721 Days
• Field of Search: 701/41, 701/42, 701/70, 180/6.2, 180/402, 180/444, 180/446
• US Class Current: 701/42
• CPC Class Codes: B62D 5/001 Mechanical components or aspects of steer-by-wire systems, not otherwise provided for in this maingroup
• CPC Class Codes: B62D 6/002 computing target steering angles for front or rear wheels B62D7/159 takes precedence
• CPC Class Codes: B62D 6/003 in order to control vehicle yaw movement, i.e. around a vertical axis B62D6/007 takes precedence

Abstract

A vehicle steering apparatus in which a mechanical coupling between a steering member and steered wheels is uncoupled, includes a steering actuator for driving a steered mechanism and a control unit for drive-controlling the steering actuator. The control unit reduces steering-stiffness using a PID control portion for drive-controlling the steering actuator according to a deviation between a target steered angle and a steered-angle detected by the steered angle sensor. A gain setting portion sets gains of the PID control portion to be relatively low when a predetermined condition is satisfied.

Claims

1. A vehicle steering apparatus in which a mechanical coupling between a steering member and steered wheels is uncoupled, the apparatus comprising:

a steering actuator for driving a steered mechanism, and

a control unit for drive-controlling the steering actuator, wherein the control unit includes steering-stiffness reducing means for reducing steering-stiffness, including a proportional integral differential control portion for drive-controlling the steering actuator according to a deviation between a target steered angle and a steered-angle detected by a steered angle sensor, and the steering-stiffness reducing means includes a gain setting portion for setting gams of the proportional integral differential control portion to be relatively low when a detected vertical acceleration of a body of the vehicle is equal to or higher than a predetermined value.

2. The vehicle steering apparatus according to claim 1, wherein the predetermined condition further includes at least one of conditions that a detected vehicle speed is equal to or higher than a predetermined value, and that a detected slip-angle is equal to or larger than a predetermined value.

3. The vehicle steering apparatus according to claim 1 further comprising:

a steered shaft configured to axially move as steered; and

a housing for supporting said steered shaft, the housing being rigidly coupled to a vehicle body.

4. The vehicle steering apparatus according to claim 1 further comprising a vertical acceleration sensor for detecting a vertical acceleration of the body of the vehicle, wherein the vertical acceleration sensor outputs a vertical acceleration signal to the gain setting portion.