STEERING CONTROL SYSTEM

• US 20170259845A1
• Filed: 03/02/2017
• Published: 09/14/2017
• Est. Priority Date: 03/10/2016
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: NOZAWA, Tetsuya, MATSUO, Shigeto
• Granted Patent: US 10,414,429 B2
• Time in Patent Office: Days
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input
• CPC Class Codes: B62D 5/0472 for damping vibrations
• CPC Class Codes: B62D 5/0484 for reaction to failures, e.g. limp home
• CPC Class Codes: B62D 5/049 detecting sensor failures

Abstract

The microcomputer calculates a first assist component based on a vehicle speed value and a steering torque, calculates a rotation angle command value based on at least the vehicle speed value and a first assist component, and calculates a second assist component by adjusting a rotation angle to the rotation angle command value through feedback control. The microcomputer sets a limited state 1 where the second assist component is disabled when a vehicle is stationary. During an abnormality determination period during which the vehicle speed value is determined to be abnormal, the microcomputer sets the vehicle speed value to a provisional vehicle speed value. Further, in a limited state 2 that is set when the vehicle is stationary during the abnormality determination period, the microcomputer calculates the first assist component based on a provisional vehicle speed value, and disables the second assist component.

Claims

1. A steering control system comprising,

a steering operation processing circuit that controls a controlled variable for a motor so as to apply a steering force for steering steered wheels to a steering device in response to an operation of a steering wheel, wherein

the steering operation processing circuit includes:

a basic controlled variable calculation circuit that calculates a first component that is a basic component of the controlled variable for the motor, based on a vehicle speed value that is a detected value of a traveling speed of a vehicle and a steering torque that is a detected value of a load applied to the steering wheel;

a rotation angle command value calculation circuit that calculates a rotation angle command value for a rotary shaft based on at least the vehicle speed value and the first component, the rotation angle command value being convertible into a steered angle of the steered wheels;

a feedback calculation processing circuit that calculates a second component of the controlled variable for the motor by adjusting a rotation angle of the rotary shaft to the rotation angle command value through feedback control, the rotation angle of the rotary shaft being a detected value;

a control processing circuit that controls an operation of the motor based on the controlled variable for the motor, the controlled variable including the first component and the second component; and

a limited-state setting circuit that sets a first limited state when the vehicle speed value is equal to or lower than a reference vehicle speed value that is a reference value at and below which it is determined that the vehicle is not traveling, the first limited state being a state where a variation range of the second component is more limited than when the vehicle speed value is higher than the reference vehicle speed value, wherein

the steering operation processing circuit sets the vehicle speed value to a provisional vehicle speed value that is higher than the reference vehicle speed value, during an abnormality determination period during which the vehicle speed value is determined to be abnormal,

the basic controlled variable calculation circuit calculates the first component based on the provisional vehicle speed value during the abnormality determination period, and

during the abnormality determination period, the limited-state setting circuit sets a second limited state where the variation range of the second component is more limited than when the vehicle speed value is not abnormal.

2. The steering control system according to claim 1, wherein the second component is limited by being disabled during the abnormality determination period.

3. The steering control system according to claim 2, wherein the limited-state setting circuit is configured to limit the second component during the abnormality determination period, when it is determined that the vehicle is not traveling based on a detected value of a physical quantity related to the vehicle, other than the vehicle speed value.

4. The steering control system according to claim 2, wherein the limited-state setting circuit is configured to cancel a limitation of the second component when it is determined that the vehicle speed value is no longer abnormal, after the limitation is imposed on the second component during the abnormality determination period.

5. The steering control system according to claim 2, wherein the second component is disabled by being set to zero during the abnormality determination period.