Apparatus and method for detecting friction characteristics

• US 5,948,961 A
• Filed: 06/04/1996
• Issued: 09/07/1999
• Est. Priority Date: 06/05/1995
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Original Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Inventors: Asano, Katsuhiro, Sugai, Masaru
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US08/659,010
• Time in Patent Office: 1,190 Days
• Field of Search: 73/9, 73/10
• US Class Current: 73/9
• 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: 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

An apparatus and method for detecting friction characteristics are disclosed, in which a wheel resonant system includes a vehicle body, a road surface and at least a wheel. A braking force control system exerts a braking force on the wheel. A resonant component detector determines a resonant gain providing the ratio between the amplitude of predetermined frequency component of the braking force and that of the wheel velocity and detects the ratio of the resonant gain to a present reference gain, a deviation calculator calculates the deviation between this ratio and unity, a PI controller controls the braking force control system in such a manner that the deviation coincides with zero, and a friction characteristics detector detects the friction characteristics on the basis of the braking force. When the friction force is made to approach a peak value by increasing the braking force, the resonant characteristics undergo a change thereby to reduce the resonant gain. By controlling the braking force in such a manner that the deviation coincides with zero, therefore, the friction characteristics are held at a peak value. This braking force reflects the friction characteristics, and therefore the friction characteristics between the road surface and the wheel can be accurately detected according to the relative magnitude of the braking force.

Claims

1. An apparatus for detecting friction characteristics comprising:

a vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element;

exciting force generating means for generating an exciting force containing selected one of the resonant frequency of said vibrating system and the frequency component in the vicinity of said resonant frequency and exciting said vibrating system by said exciting force;

vibration response detecting means for detecting the quantity of state of the vibration response of said vibrating system excited by said exciting force generating means;

resonant characteristics calculating means for calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the exciting force generated by said exciting force generating means and the quantity of state of the vibration response detected by said vibration response detecting means; and

friction characteristics calculation means for calculating the friction characteristics of the contact surface on the basis of the resonant characteristics calculated by said resonant characteristics calculating means.

2. An apparatus for detecting friction characteristics comprising:

a vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element, said vibrating system being excited by an external force;

external force detecting means for detecting the quantity of state of said external force;

vibration response detecting means for detecting the quantity of state of the vibration response of said vibrating system excited by said external force;

resonant characteristics calculating means for calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of said external force detected by said external force detecting means and the quantity of state of the vibration response detected by said vibration response detecting means; and

friction characteristics calculating means for calculating the friction characteristics of the contact surface on the basis of the resonant characteristics calculated by said resonant characteristics calculating means.

3. An apparatus for detecting friction characteristics comprising:

a vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element;

exciting means for exciting said vibrating system in the direction of generation of the friction force by the exciting force containing selected one of the resonant frequency of said vibrating system and the frequency component in the vicinity of said resonant frequency;

vibration response detecting means for detecting the quantity of state of the vibration response of said vibrating system excited by said exciting means;

resonant characteristics calculating means for calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the exciting force generated by said exciting means and the quantity of state of the vibration response detected by said vibration response detecting means;

operating force generating means for generating and exerting the operating force on said contact surface;

maximum friction force control means for controlling said operating force on the basis of the resonant characteristics calculated by said resonant characteristics calculating means in such a manner that said contact surface assumes a state just about to slip; and

friction characteristics calculation means for calculating the friction characteristics of the contact surface on the basis of the maximum friction force of the maximum friction force control means.

4. An apparatus according to claim 3, further comprising:

maximum friction force calculating means for calculating the value of maximum friction force of the contact surface on the basis of the operating force associated with the state of said contact surface just about to slip realized by said maximum friction force control means; and

friction coefficient calculating means for calculating the friction coefficient of said contact surface on the basis of the value of the maximum friction force calculated by said maximum friction force calculating means.

5. An apparatus for detecting friction characteristics comprising:

a vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element, said vibrating system being excited by an external force;

external force detecting means for detecting the quantity of state of said external force;

vibration response detecting means for detecting the quantity of state of the vibration response of said vibrating system excited by said external force;

resonant characteristics calculating means for calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the external force detected by said external force detecting means and the quantity of state of the vibration response detected by said vibration response detecting means;

operating force generating means for generating and exerting an operating force on said contact surface;

maximum friction force control means for controlling said operating force on the basis of the resonant characteristics calculated by said resonant characteristics calculating means in such a manner that said contact surface assumes a state just about to slip; and

friction characteristics calculation means for calculating the friction characteristics of the contact surface on the basis of the maximum friction force of the maximum friction force control means.

6. An apparatus according to claim 5, further comprising:

maximum friction force calculating means for calculating the value of maximum friction force of the contact surface on the basis of the operating force associated with the state of said contact surface just about to slip realized by said maximum friction force control means; and

friction coefficient calculating means for calculating the friction coefficient of said contact surface on the basis of the value of the maximum friction force calculated by said maximum friction force calculating means.

7. A method for detecting friction characteristics comprising the steps of:

forming a vibrating system, said vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element;

generating an exciting force containing selected one of the resonant frequency of said vibrating system and the frequency component in the vicinity of said resonant frequency and exciting said vibrating system by said exciting force;

detecting the quantity of state of the vibration response of said vibrating system excited by said exciting force generating step;

calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the exciting force generated by said exciting force generating step and the quantity of state of the vibration response detected by said vibration response detecting step; and

calculating the friction characteristics of the contact surface on the basis of the resonant characteristics calculated by said resonant characteristics calculating step.

8. A method for detecting friction characteristics comprising the steps of:

forming a vibrating system, said vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element, and said vibrating system being excited by an external force;

detecting the quantity of state of said external force;

detecting the quantity of state of the vibration response of said vibrating system excited by said external force;

calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of said external force detected by said external force detecting step and the quantity of state of the vibration response detected by said vibration response detecting step; and

calculating the friction characteristics of the contact surface on the basis of the resonant characteristics calculated by said resonant characteristics calculating step.

9. A method for detecting friction characteristics comprising the steps of:

forming a vibrating system, said vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element;

exciting said vibrating system in the direction of generation of the friction force by the exciting force containing selected one of the resonant frequency of said vibrating system and the frequency component in the vicinity of said resonant frequency;

detecting the quantity of state of the vibration response of said vibrating system excited by said exciting step;

calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the exciting force generated by said exciting step and the quantity of state of the vibration response detected by said vibration response detecting step;

generating and exerting an operating force on said contact surface;

controlling said operating force on the basis of the resonant characteristics calculated by said resonant characteristics calculating step in such a manner that said contact surface assumes a state just about to slip; and

calculating the friction characteristics of the contact surface on the basis of the maximum friction force of the maximum friction force control step.

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

calculating the value of maximum friction force of the contact surface on the basis of the operating force associated with the state of said contact surface just about to slip realized by said operation force control step; and

calculating the friction coefficient of said contact surface on the basis of the value of the maximum friction force calculated by said maximum friction force calculating step.

11. A method for detecting friction characteristics comprising the steps of:

forming a vibrating system, said vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element, and said vibrating system being excited by an external force;

detecting the quantity of state of said external force;

detecting the quantity of state of the vibration response of said vibrating system excited by said external force;

calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the external force detected by said external force detecting step and the quantity of state of the vibration response detected by said vibration response detecting step;

generating and exerting an operating force on said contact surface;

controlling said operating force on the basis of the resonant characteristics calculated by said resonant characteristics calculating step in such a manner that said contact surface assumes a state just about to slip; and

calculating the friction characteristics of the contact surface on the basis of the maximum friction force of the maximum friction force control step.

12. A method according to claim 11, further comprising the steps of:

calculating the value of maximum friction force of the contact surface on the basis of the operating force associated with the state of said contact surface just about to slip realized by said operation force control step; and

calculating the friction coefficient of said contact surface on the basis of the value of the maximum friction force calculated by said maximum friction force calculating step.

13. An apparatus for detecting friction characteristics comprising:

a vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element;

exciting means for exciting said vibrating system in the direction of generation of the friction force by the exciting force containing selected one of the resonant frequency of said vibrating system and the frequency component in the vicinity of said resonant frequency;

vibration response detecting means for detecting the quantity of state of the vibration response of said vibrating system excited by said exciting means;

resonant characteristics calculating means for calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the exciting force generated by said exciting means and the quantity of state of the vibration response detected by said vibration response detecting means;

operating force generating means for generating and exerting the operating force on said contact surface;

maximum friction force control means for controlling said operating force on the basis of the resonant characteristics calculated by said resonant characteristics calculating means in such a manner that said contact surface assumes a state just about to slip;

maximum friction force calculating means for calculating the value of maximum friction force of the contact surface on the basis of the operating force associated with the state of said contact surface just about to slip realized by said maximum friction force control means; and

friction coefficient calculating means for calculating the friction coefficient of said contact surface on the basis of the value of the maximum friction force calculated by said maximum friction force calculating means.

14. An apparatus for detecting friction characteristics comprising:

a vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element, said vibrating system being excited by an external force;

external force detecting means for detecting the quantity of state of said external force;

vibration response detecting means for detecting the quantity of state of the vibration response of said vibrating system excited by said external force;

resonant characteristics calculating means for calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the external force detected by said external force detecting means and the quantity of state of the vibration response detected by said vibration response detecting means;

operating force generating means for generating and exerting an operating force on said contact surface;

maximum friction force control means for controlling said operating force on the basis of the resonant characteristics calculated by said resonant characteristics calculating means in such a manner that said contact surface assumes a state just about to slip;

maximum friction force calculating means for calculating the value of maximum friction force of the contact surface on the basis of the operating force associated with the state of said contact surface just about to slip realized by said maximum friction force control means; and

friction coefficient calculating means for calculating the friction coefficient of said contact surface on the basis of the value of the maximum friction force calculated by said maximum friction force calculating means.

15. A method for detecting friction characteristics, comprising the steps of:

forming a vibrating system, said vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element;

exciting said vibrating system in the direction of generation of the friction force by the exciting force containing a selected one of the resonant frequency of said vibrating system and the frequency component in the vicinity of said resonant frequency;

detecting the quantity of state of the vibration response of said vibrating system excited by said exciting step;

calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the exciting force generated by said exciting step and the quantity of state of the vibration response detected by said vibration response detecting step;

generating and exerting an operating force on said contact surface;

controlling said operating force on the basis of the resonant characteristics calculated by said resonant characteristics calculating step in such a manner that said contact surface assumes a state just about to slip;

calculating the value of maximum friction force of the contact surface on the basis of the operating force associated with the state of said contact surface just about to slip realized by said operation force control step; and

calculating the friction coefficient of said contact surface on the basis of the value of the maximum friction.

16. A method for detecting friction characteristics, comprising the steps of:

forming a vibrating system, said vibrating system including an element on one side of a contact surface generating a friction force, a spring element connected to said element and adapted to be displaced in the direction substantially parallel to said contact surface and an inertial member connected to the other end of said spring element, and said vibrating system being excited by an external force;

detecting the quantity of state of said external force;

detecting the quantity of state of the vibration response of said vibrating system excited by said external force;

calculating the resonant characteristics of said vibrating system on the basis of the quantity of state of the external force detected by said external force detecting step and the quantity of state of the vibration response detected by said vibration response detecting step;

generating and exerting an operating force on said contact surface;

controlling said operating force on the basis of the resonant characteristics calculated by said resonant characteristics calculating step in such a manner that said contact surface assumes a state just about to slip;

calculating the value of maximum friction force of the contact surface on the basis of the operating force associated with the state of said contact surface just about to slip realized by said operation force control step; and

calculating the friction coefficient of said contact surface on the basis of the value of the maximum friction force calculated by said maximum friction force calculating step.