Method and apparatus for learning neutral position of vehicle steering angle

• US 5,253,172 A
• Filed: 01/23/1991
• Issued: 10/12/1993
• Est. Priority Date: 01/25/1990
• Status: Expired due to Term

• Current Assignee: Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Original Assignee: Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Inventors: Yamada, Kiichi, Ito, Masayoshi, Otake, Katsunori, Miyata, Yasunobu, Hashiguchi, Masayuki
• Primary Examiner(s): Harvey, Jack B.
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US07/645,043
• Time in Patent Office: 993 Days
• Field of Search: 364/424.05, 180/79, 180/142, 180/79.1, 318/565, 340/465, 340/475-477, 340/549, 340/672
• US Class Current: 701/41
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00
• CPC Class Codes: B60T 2201/16 Curve braking control, e.g. turn control within ABS control algorithm
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16
• CPC Class Codes: B62D 15/02 Steering position indicators ; Steering position determination; Steering aids

Abstract

A method and apparatus for learning the neutral position of vehicle steering angle, in which first neutral position decision means decides that the steering shaft is at a neutral position when a running speed detector detects that the vehicle speed is not less than a predetermined threshold level, that the difference in peripheral speed between the right and left drive wheels is smaller than a predetermined first straight-running threshold value and also when a steering shaft reference position sensor continues to detect a reference position of the steering shaft for at least a first count time. The vehicle steering angle is computed on the basis of the angular displacement from the neutral position thus learned.

Claims

1. A method of learning a neutral position of a vehicle steering angle, comprising:

detecting a reference position of a steering shaft by a steering shaft reference position sensor;

detecting a turning angle of said steering shaft by a steering angle detection means;

detecting the peripheral speeds of right and left driven wheels of the vehicle and a running speed of the vehicle by running speed detection means; and

deciding said neutral position of said steering angle by first neutral position decision means, said first neutral position decision means deciding said neutral position of said steering angle wherein the following four criteria are satisfied, first, when said vehicle running speed is not less than a first predetermined threshold value, second, when a difference in peripheral speed between said right and left driven wheels is smaller than a second predetermined threshold value;

third, when said steering shaft reference position sensor continues to detect said reference position of said steering shaft within a predetermined range for at least a first count time and fourth, when said steering angle detection means continues to detect substantially the same turning angle for at least said first count time.

2. A method according to claim 1, wherein deciding said neutral position of said steering angle further comprises deciding said neutral position by second neutral position decision means, said second neutral position decision means deciding said neutral position of said steering angle wherein the following three criteria are satisfied, first, when said vehicle running speed is not less than said first predetermined threshold value, second, when said difference between peripheral speeds of said right and left driven wheels is smaller than a third predetermined threshold value and third, when said second condition that said difference between the peripheral speeds of said right and left driven wheels is smaller than said third predetermined threshold value continues to be detected for at least a second count time, and

selectively using said first neutral position decision means and said second neutral position decision means.

3. A method according to claim 1, where said second predetermined threshold value is changed in accordance with said vehicle running speed.

4. A method according to claim 1, wherein said neutral position of said steering angle obtained by a previous learning is changed only up to a predetermined maximum amount in second and subsequent learnings of said neutral position.

5. An apparatus for learning a neutral position of a vehicle steering angle, comprising:

a steering shaft reference position sensor for detecting a reference position of a steering shaft;

running speed detection means for detecting peripheral speeds of right and left driven wheels of the vehicle and a running speed of the vehicle;

steering angle detection means for detecting a turning angle of said steering shaft; and

a first neutral position decision means for deciding on said neutral position, said first neutral position decision means deciding said neutral position of said steering angle wherein the following four criteria are satisfied, first, when said running speed detection means detects that said vehicle running speed is not less than a first predetermined threshold value, second, that a difference in peripheral speed between said right and left driven wheels is smaller than a second predetermined threshold value, third, when said steering shaft reference position sensor continues to detect a reference position of said steering shaft within a predetermined range for at least a first count time and fourth, when said steering angle detection means continues to detect substantially the same turning angle for at least said first count time.

6. An apparatus according to claim 5, further comprising a second neutral position decision means connected in parallel to said first neutral position decision means for deciding on said neutral position when the following three criteria are satisfied, first, when said running speed detection means detects that said vehicle running speed is not less than said first predetermined threshold value, second, when said difference between peripheral speeds of said right and left driven wheels is smaller than a third predetermined threshold value and third, that said difference in peripheral speed between said right and left driven wheels continues to be smaller than said third predetermined threshold value for at least a second count time, and means for selecting one of said first neutral position decision means and said second neutral position decision means.

7. An apparatus according to claim 5, wherein said first neutral position decision means includes therein means for changing said second predetermined threshold value in accordance with said vehicle running speed.

8. An apparatus according to claim 5, further comprising means for preventing said neutral position of said steering shaft from being changed by more than a predetermined maximum amount as compared with a steering shaft neutral position determined by a previous learning in second and subsequent processes of learning of said neutral position.

9. A method of learning a neutral position of a vehicle steering angle, comprising:

detecting a reference position of a steering shaft within a predetermined range;

detecting a turning angle of said steering shaft;

detecting peripheral speeds of right and left driven wheels of the vehicle and a running speed of the vehicle; and

deciding a neutral position of said steering angle when the following four criteria are satisfied, first, when said vehicle running speed is not less than a first predetermined threshold value, second, when a difference in peripheral speed between said right and left driven wheels is smaller than a second predetermined threshold value, third, when said detection of said reference position of said steering shaft within a predetermined range continues for at least a first count time and fourth, when said detected turning angle remains unchanged for said first count time.

10. A method according to claim 9, further comprising:

deciding a neutral position of said steering angle when the following three criteria are satisfied, first, when said vehicle running speed is not less than said first predetermined threshold value, second, when said difference in peripheral speed between said right and left driven wheels is smaller than a third predetermined threshold value and third, when said difference in peripheral speed between said right and left driven wheels continues to be smaller than said third predetermined threshold value for at least a second count time.

11. A method according to claim 9, further comprising:

changing said second predetermined threshold value in accordance with said vehicle running speed.

12. A method according to claim 9, wherein said neutral position of said steering angle obtained by a previous learning is changed only up to a predetermined maximum amount in second and subsequent learnings of said neutral position.