Vehicle steering control system

• US 6,751,539 B2
• Filed: 09/12/2002
• Issued: 06/15/2004
• Est. Priority Date: 09/17/2001
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Uenuma, Kenya, Mouri, Hiroshi
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Gibson, Eric M.
• Application Number:
  US10/241,781
• Publication Number:
  US 20030055545A1
• Time in Patent Office: 642 Days
• Field of Search: 701/41, 701/42, 701/44, 340/465, 180/402, 180/443, 180/446
• US Class Current: 701/41
• 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

In a steering mechanism of steer-by-wire type which includes a first steering unit that is handled by a driver and a second steering unit that steers steered road wheels with the aid of a steering motor, there is employed a control system which input and output detecting sections that detect input and output of the steering motor, a road surface disturbance estimating section that estimates a disturbance of road surface based on both the detected input and output of the steering motor, and a steering reaction force calculating section that, based on the estimated disturbance of road surface, calculates a steering reaction force that is to be applied to a steering wheel of the first steering unit.

Claims

1. A vehicle steering control system for use with a steering mechanism of steer-by-wire type, the steering mechanism including a first steering unit that is handed by a driver and a second steering unit that steers steered road wheels with the aid of a steering actuator, the first and second steering units being mechanically unconnected,

the vehicle steering control system comprising:

a steering reaction force actuator that generates a steering reaction force that is to be applied to the first steering unit in accordance with a steered movement of the steered road wheels;

an input detecting section that detects an input applied to the steering actuator;

an output detecting section that detects an output issued from the steering actuator;

a road surface disturbance estimating section that estimates a disturbance of road surface based on both the detected input and output of the steering actuator;

a steering reaction force calculating section that, based on the estimated disturbance of road surface, calculates a steering reaction force which is to be applied to the first steering unit; and

a steering reaction force control section that instructs the steering reaction force actuator to generate a steering reaction force in accordance with the calculated steering reaction force.

2. A vehicle steering control system as claimed in claim 1, in which the steering reaction force calculating section comprises:

a first steering reaction force calculating part that calculates a first steering reaction force based on the estimated disturbance of road surface;

a second steering reaction force calculating part that calculates a second steering reaction force based on a behavior of an associated motor vehicle; and

a third steering reaction force calculating part that, by subtracting the calculated first steering reaction force from the calculated second steering reaction force, calculates a final steering reaction force that is actually applied to the steering reaction force actuator.

3. A vehicle steering control system as claimed in claim 1, further comprising a filter through which a signal of the output from the output detecting section is led into the road surface disturbance estimating section.

4. A vehicle steering control system as claimed in claim 3, in which the filter is a first order lag filter.

5. A vehicle steering control system as claimed in claim 1, further comprising a filter through which a signal of the estimated disturbance of road surface from the road surface disturbance estimating section is led into the steering reaction force calculating section.

6. A vehicle steering control system as claimed in claim 5, in which the filter is a second order lag filter.

7. A vehicle steering control system as claimed in claim 1, in which the road surface disturbance estimating section comprises:

a first block that processes the detected input to estimate a first torque in the form of transfer function;

a second block that processes the detected output to estimate a second torque in the form of transfer function; and

a calculating section that calculates a difference between the estimated first torque and the estimated second torque.

8. A vehicle steering control system for use with a steering mechanism of steer-by-wire type, the steering mechanism including a first steering unit that is handed by a driver and a second steering unit that steers steered road wheels with the aid of a steering actuator, the first and second steering units being mechanically unconnected,

the vehicle steering control system comprising:

a steering reaction force generating means that generates a steering reaction force that is to be applied to the first steering unit in accordance with a steered movement of the steered road wheels;

an input detecting means that detects an input applied to the steering actuator;

an output detecting means that detects an output issued from the steering actuator;

a road surface disturbance estimating means that estimates a disturbance of road surface based on both the detected input and output of the steering actuator;

a steering reaction force calculating means that, based on the estimated disturbance of road surface, calculates a steering reaction force which is to be applied to the first steering unit; and

a steering reaction force control means that instructs the steering reaction force actuator to generate a steering reaction force in accordance with the calculated steering reaction force.

9. In a vehicle steering control system for use with a steering mechanism of steer-by-wire type, the steering mechanism including a first steering unit that is handed by a driver and a second steering unit that steers steered road wheels without a direct aid of the first steering unit, a steering actuator that actuates the second steering unit and a steering reaction force actuator that applies a steering reaction force to the first steering unit in accordance with a steered movement of the steered road wheels,

a method of controlling the vehicle steering control system comprising:

detecting an input applied to the steering actuator;

detecting an output issued from the steering actuator;

estimating a disturbance of road surface based on both the detected input and output of the steering actuator;

calculating, based on the estimated disturbance of road surface, a steering reaction force which is to be applied to the first steering unit; and

instructing the steering reaction force actuator to generate a steering reaction force in accordance with the calculated steering reaction force.