Stick-slip detection method and apparatus

• US 5,750,879 A
• Filed: 05/28/1997
• Issued: 05/12/1998
• Est. Priority Date: 05/31/1996
• Status: Expired due to Term

• Current Assignee: Yamatake-Honeywell Company Limited
• Original Assignee: Yamatake-Honeywell Company Limited
• Inventors: Kaseda, Chosei, Ohtsuka, Akira
• Primary Examiner(s): Biegel, Ronald L.
• Assistant Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US08/864,242
• Time in Patent Office: 349 Days
• Field of Search: 73/1.79, 73/7, 73/9, 73/11.09, 73/865.3, 73/865.9, 55/270, 55/274
• US Class Current: 73/9
• CPC Class Codes: G01N 19/02 Measuring coefficient of friction between materials testing of tyres G01M17/02; determinations of friction coefficient used in vehicle braking or traction control systems B60T8/172

Abstract

In a stick-slip detection method, the displacement of a movable member having a slidable contact portion is detected. A first quantity of state is calculated on the basis of the detected displacement of the movable member. A second quantity of state, which can be estimated from the first quantity of state, is calculated on the basis of the detected displacement of the movable member. An estimated quantity of state is calculated by estimating a second quantity of state from the calculated first quantity of state by using the relationship between the first and second predetermined quantities of state which are obtained from the displacement of the movable member in a normal sliding state. The calculated second quantity of state is compared with the estimated quantity of state to determine an abnormal sliding operation of the movable member on the basis of the comparison result. A stick-slip detection apparatus is also disclosed.

Claims

1. A stick-slip detection method comprising the steps of:

detecting a displacement of a movable member having a slidable contact portion;

calculating a first quantity of state on the basis of the detected displacement of the movable member;

calculating a second quantity of state, which can be estimated from the first quantity of state, on the basis of the detected displacement of the movable member;

calculating an estimated quantity of state by estimating a second quantity of state from the calculated first quantity of state by using a relationship between first and second predetermined quantities of state which are obtained from a displacement of the movable member in a normal sliding state; and

comparing the calculated second quantity of state with the estimated quantity of state, and determining an abnormal sliding operation of the movable member on the basis of the comparison result.

2. A method according to claim 1, wherein the step of calculating the first quantity of state comprises the step of detecting a small amount of change in the displacement of the movable member, and

the step of calculating the second quantity of state comprises the step of detecting a small amount of change in the small amount of change in the displacement of the movable member.

3. A method according to claim 1, wherein the step of calculating the first quantity of state comprises the step of calculating an average of first order difference values of the displacement of the movable member, and

the step of calculating the second quantity of state comprises the step of calculating an average of squares of the first order difference values of the displacement of the movable member.

4. A stick-slip detection method comprising the steps of:

detecting a displacement of a movable member having a slidable contact portion;

calculating a first quantity of state on the basis of the detected displacement of the movable member;

calculating a second quantity of state having a predetermined relationship with the first quantity of state on the basis of the detected displacement of the movable member; and

comparing a relationship between the calculated first and second quantities of state with a relationship between first and second predetermined quantities of state which are obtained from a displacement of the movable member in a normal sliding state, and determining an abnormal sliding operation of the movable member on the basis of the comparison result.

5. A method according to claim 4, wherein the step of calculating the first quantity of state comprises the step of detecting a small amount of change in the displacement of the movable member, and

the step of calculating the second quantity of state comprises the step of detecting a small amount of change in the small amount of change in the displacement of the movable member.

6. A method according to claim 4, wherein the step of calculating the first quantity of state comprises the step of calculating an average of first order difference values of the displacement of the movable member, and

the step of calculating the second quantity of state comprises the step of calculating an average of squares of the first order difference values of the displacement of the movable member.

7. A stick-slip detection apparatus comprising:

displacement detecting means for detecting a displacement of a movable member having a slidable contact portion;

first calculating means for calculating a first quantity of state on the basis of the displacement of the movable member which is obtained by said displacement detecting means;

second calculating means for calculating a second quantity of state, which can be estimated from the first quantity of state, on the basis of the displacement of the movable member which is obtained by said displacement detecting means;

characteristic storage means in which a relationship between first and second quantities of state obtained from a displacement of the movable member in a normal sliding state is stored;

quantity-of-state estimating means for calculating an estimated quantity of state by estimating a second quantity of state from the first quantity of state obtained by said first calculating means by using the relationship in the normal sliding state which is stored in said characteristic storage means; and

diagnosis calculating means for comparing the second quantity of state obtained by said second calculating means with the estimated quantity of state obtained by said quantity-of-state estimating means, and determining an abnormal sliding operation of the movable member on the basis of the comparison result.

8. An apparatus according to claim 7, wherein the first quantity of state calculated by said first calculating means is a small amount of change in the displacement of the movable member, and

the second quantity of state calculated by said second calculating means is a small amount of change in the small amount of change in the displacement of the movable member.

9. An apparatus according to claim 7, wherein the first quantity of state calculated by said first calculating means is an average of first order difference values of the displacement of the movable member, and

the second quantity of state calculated by said second calculating means is an average of squares of the first order difference values of the displacement of the movable member.

10. A stick-slip detection apparatus comprising:

displacement detecting means for detecting a displacement of a movable member having a slidable contact portion;

first calculating means for calculating a first quantity of state on the basis of the displacement of the movable member which is obtained by said displacement detecting means;

second calculating means for calculating a second quantity of state having a predetermined relationship with the first quantity of state on the basis of the displacement of the movable member which is obtained by said displacement detecting means;

characteristic storage means in which a relationship between first and second quantities of state obtained from a displacement of the movable member in a normal sliding state is stored; and

diagnosis calculating means for comparing a relationship between the first quantity of state obtained by said first calculating means and the second quantity of state obtained by said second calculating means with the relationship in the normal sliding state which is stored in said characteristic storage means, and determining an abnormal sliding operation of the movable member on the basis of the comparison result.

11. An apparatus according to claim 10, wherein the first quantity of state calculated by said first calculating means is a small amount of change in the displacement of the movable member, and

the second quantity of state calculated by said second calculating means is a small amount of change in the small amount of change in the displacement of the movable member.

12. An apparatus according to claim 10, wherein the first quantity of state calculated by said first calculating means is an average of first order difference values of the displacement of the movable member, and

the second quantity of state calculated by said second calculating means is an average of squares of the first order difference values of the displacement of the movable member.

13. A stick-slip detection apparatus comprising:

displacement detecting means for detecting a displacement of a movable member having a slidable contact portion;

difference calculating means for calculating first order difference values of the displacement of the movable member which is obtained by said displacement detecting means;

first sum total calculating means for calculating a sum of the first order difference values obtained by said difference calculating means;

first average calculating means for calculating a first quantity of state from an average of at least part of the sum of the first order difference values which is obtained by said first sum total calculating means;

second sum total calculating means for calculating a square sum of the first order difference values obtained by said difference calculating means;

second average calculating means for calculating a second quantity of state from an average of at least part of the square sum of the first order difference values which is obtained by said second sum total calculating means;

characteristic storage means in which a relationship between first and second quantities of state which are obtained from a displacement of the movable member in a normal sliding state is stored;

quantity-of-state estimating means for calculating an estimated quantity of state by estimating a second quantity of state from the first quantity of state obtained by said first average calculating means by using the relationship in the normal sliding state which is stored in said characteristic storage means; and

diagnosis calculating means for comparing the second quantity of state obtained by said second average calculating means with the estimated quantity of state obtained by said quantity-of-state estimating means, and determining an abnormal sliding operation of the movable member on the basis of the comparison result.

14. A stick-slip detection apparatus comprising:

displacement detecting means for detecting a displacement of a movable member having a slidable contact portion;

difference calculating means for calculating first order difference values of the displacement of the movable member which is obtained by said displacement detecting means;

first sum total calculating means for calculating a sum of the first order difference values obtained by said difference calculating means;

first average calculating means for calculating a first quantity of state from an average of at least part of the sum of the first order difference values which is obtained by said first sum total calculating means;

second sum total calculating means for calculating a square sum of the first order difference values obtained by said difference calculating means;

second average calculating means for calculating a second quantity of state from an average of at least part of the square sum of the first order difference values which is obtained by said second sum total calculating means;

characteristic storage means in which a relationship between first and second quantities of state which are obtained from a displacement of the movable member in a normal sliding state is stored; and

diagnosis calculating means for comparing a relationship between the first quantity of state obtained by said first average calculating means and the second quantity of state obtained by said second average calculating means with the relationship in the normal sliding state which is stored in said characteristic storage means.