Systems And Methods For Determining A Parameter Relating A Tire-to-Road Contact And/Or A Relation Between A Wheel And A Vehicle Motion

• US 20080243348A1
• Filed: 03/03/2008
• Published: 10/02/2008
• Est. Priority Date: 03/01/2007
• Status: Active Grant

• Current Assignee: Volvo Car Corporation (AB Volvo), Haldex Brake Products AB (SAF-HOLLAND SE)
• Original Assignee: Volvo Car Corporation (AB Volvo)
• Inventors: Hulten, Johan, Svendenius, Jacob, Gaefvert, Magnus, Bruzelius, Federik
• Granted Patent: US 8,065,067 B2
• Time in Patent Office: Days
• US Class Current: 701/90
• 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

Abstract

The present invention refers to systems and to methods for determining at least one parameter relating to a tire-to-road contact and/or a relation between a wheel and a vehicle motion. In particular, the present invention refers to systems and to methods for determining the coefficient of friction between a tire and a road surface. For that purpose, the systems and methods according to the invention use new estimation filtering procedures.

Claims

1. Method for determining at least one of a coefficient of friction and a tire stiffness of a tire method comprising the steps of:

sensing a plurality of parameters related to a vehicle motion,

determining said at least one of the coefficient of friction and the tire stiffness from a relationship defined by at least two parameters relating to the tire and/or vehicle motion using estimation filtering procedures;

characterized in that the estimation filtering procedures comprise the steps of;

defining a set of data bins corresponding to intervals which are defined for values of said at least two parameters relating to the tire and/or vehicle motion, respectively,

continuously determining an actual value of a first one of said at least two parameters and selecting the data bins corresponding to said actual value of the first one of said at least two parameters and updating and storing values of the first one of said at least two parameters and of a second one of said at least two parameters in said selected data bins, respectively, and/or

continuously determining an actual value of the second one of said at least two parameters and selecting the data bins corresponding to said actual value of the second one of said at least two parameters and updating and storing values of the second one of said at least two parameters and of the first one of said at least two parameters in said selected data bins, respectively.

2. Method according to claim 1, wherein the data bins are defined for values of more than two parameters relating to the tire and/or vehicle motion, respectively.

3. Method according to claim 1, wherein the steps of updating the values of the at least two parameters in the data bins include the step of:

averaging over the previously stored value of the first one of said at least two parameters or the previously stored value of the second one of said at least two parameters and the determined actual value of the first one of said at least two parameters or the determined actual value of the second one of said at least two parameters respectively.

4. Method according to claim 1, further comprising the steps of:

assessing the importance of the values of the at least two parameters within each of the selected data bins, respectively, and/or

assessing the confidence of the values of the at least two parameters within each of the selected data bins, respectively.

5. Method according to claim 1, further comprising the steps of:

detecting a defined change in at least one of the at least two parameters, and

clearing and resetting the data bins.

6. Method according to claim 5, wherein the change is detected in at least one of the data bins.

7. Method according to claim 1 further comprising the step of:

continuously adapting said relationship to said updated values of the at least two parameters in the data bins, respectively.

8. Method according to claim 1, wherein the first one of said at least two parameters is a tire force and the second one of said at least two parameters is a tire slip.

16. Use of the method according to claim 1 in at least one assistance system of a vehicle.

9. Method for determining at least one of a coefficient of friction and a tire stiffness of a tire the method comprising the steps of:

sensing a plurality of parameters related to a vehicle motion,

determining said at least one of the coefficient of friction and the tire stiffness from a relationship defined by at least two parameters relating to the tire and/or vehicle motion using estimation filtering procedures;

characterized in that the estimation filtering procedures comprise the steps of;

defining a finite set of values for the at least two parameters respectively,

identifying values for the at least two parameters respectively, which correspond to said finite sets based on said relationship,

determining the actual value of a first one of the at least two parameters and/or the actual value of a second one of the at least two parameters and

selecting the at least one of the coefficient of friction and the tire stiffness which corresponds to the values for the first one of the at least two parameters and/or for the second one of the at least two parameters based on said relationship which are closest to the determined actual value of the first one of the at least two parameters and/or the actual value of the second one of the at least two parameters respectively.

10. Method according claim 9, further comprising the step of:

limiting the estimation filtering to a defined time frame.

12. Method according to claim 9, further comprising the steps of:

continuously applying corrective filtering procedures to said sensed parameters, and

updating the continuously corrected values in said relationship.

13. Method according to claim 12, wherein a value of a rolling radius of the tire is corrected.

14. Method according to claim 9, wherein the steps are performed to determine the different parameters for the longitudinal direction and/or for the lateral direction of the tire.

15. Use of the method according to claim 9 in at least one assistance system of a vehicle.

11. (canceled)

17. System for determining at least one of a coefficient of friction and a tire stiffness of a tire the system comprising;

a plurality of sensors for sensing a plurality of parameters related to a vehicle motion,

a control unit with at least one memory, in which memory a relationship defined by at least two parameters relating to the tire and/or vehicle motion is stored,

at least one filter operative to determine said at least one of the coefficient of friction and the tire stiffness,

characterized in that the filter comprises;

means operative to define a set of data bins corresponding to intervals which are defined for values of said at least two parameters relating to the tire and/or vehicle motion, respectively,

means operative to continuously determine an actual value of a first one of said at least two parameters and to select the data bins corresponding to said actual value of the first one of said at least two parameters, wherein said means are further operative to update and to store values of the first one of said at least two parameters, and of a second one of said at least two parameters in said selected data bins, respectively, and/or

means operative to continuously determine an actual value of the second one of said at least two parameters and to select the data bins corresponding to said actual value of the second one of said at least two parameters, wherein said means are further operative to update and to store values of the second one of said at least two parameters and the first one of said at least two parameters in said selected data bins, respectively.

18. System according to claim 17, wherein the means operative to continuously determine actual values of the at least two parameters respectively, are further adapted;

to average over the previously stored value of the first one of said at least two parameters or the previously stored value of the second one of said at least two parameters and the determined actual value of the first one of said at least two parameters or the determined actual value of the second one of said at least two parameters respectively.

19. System according to claim 17, wherein the at least one filter further comprises;

means operative to assess the importance of the values of the at least two parameters within each of the selected data bins, respectively, and/or

means to assess the confidence of the values of the at least two parameters within each of the selected data bins, respectively.

20. System according to claim 17, wherein the at least one filter further comprises means operative:

to detect a defined change in at least one of the at least two parameters, and

to clear and reset the data bins.

21. System according to claim 20, wherein the means operative to detect a defined change in at least one of the at least two parameters are adapted to detect said defined change in at least one of the data bins.

22. System according to claim 21, wherein the control unit is designed to continuously adapt said relationship to said updated values of the at least two parameters in the data bins, respectively.

23. System according to claim 17, wherein the first one of said at least two parameters is a tire force and the second one of said at least two parameters is a tire slip.

31. Use of the system according to claim 17 in at least one assistance system of a vehicle.

24. System for determining at least one of a coefficient of friction and a tire stiffness the system comprising;

a plurality of sensors for sensing a plurality of parameters related to the a vehicle motion,

a control unit with at least one memory, in which memory a relationship defined by at least two parameters relating to the tire and/or vehicle motion is stored,

at least one filter operative to determine said at least one of a coefficient of friction and a tire stiffness of a tire,

characterized in that the filter comprises;

means operative to define a finite set of values for the at least two parameters respectively,

means operative to identify values for the at least two parameters respectively, which correspond to said finite sets based on said relationship,

means operative to determine the actual value of a first one of the at least two parameters and/or the actual value of a second one of the at least two parameters and

means operative to select the at least one of the coefficient of friction and the tire stiffness which corresponds to the values for the first one of the at least two parameters and/or for the second one of the at least two parameters based on said relationship which are closest to the determined actual value of the first one of the at least two parameters and/or the actual value of the second one of the at least two parameters respectively.

25. System according to claim 24, wherein the at least one filter further comprises:

means operative to limit the filtering to a defined time frame.

27. System according to claim 24, wherein the control unit is further adapted

to continuously apply corrective filtering procedures by at least one filter to said sensed parameters, and

to update the continuously corrected values in said relationship.

28. System according to claim 27, wherein the control unit is adapted to continuously correct a value of a rolling radius of the tire.

29. System according to claim 24, wherein the control unit is further adapted to determine the different parameters for the longitudinal direction and/or for the lateral direction of the tire.

30. Use of the system according to claim 24 in at least one assistance system of a vehicle.

26. (canceled)

32. Method for determining at least one of a coefficient of friction and a tire stiffness of a tire wherein a control unit:

receives first signals from sensors representing a plurality of parameters related to a vehicle motion,

receives second signals from a memory representing a relationship defined by at least two parameters relating to the tire and/or the vehicle motion,

transmits third signals to at least one filter representing the definition of a set of data bins corresponding to intervals which are defined for values of said at least two parameters relating to the tire and/or the vehicle motion,

transmits fourth signals to the at least one filter representing the determination of an actual value of a first one of said at least two parameters and/or of a second one of said at least two parameters,

receives fifth signals from said at least one filter representing updated and stored values of the first one of said at least two parameters and of the second one of said at least two parameters in data bins, respectively, which data bins have been selected by the at least one filter on basis of the fourth signals.

34. Method according to claim 32, wherein the control unit:

transmits sixth signals representing the at least one of the coefficient of friction and the tire stiffness to be determined to an assistance system of the vehicle for further processing.

33. Method for determining at least one of a coefficient of friction and a tire stiffness of a tire wherein a control unit:

receives first signals from sensors representing a plurality of parameters related to a vehicle motion,

receives second signals from a memory representing a relationship defined by at least two parameters relating to the tire and/or the vehicle motion,

transmits third signals to at least one filter representing the definition of a finite set of values of the at least two parameters respectively,

transmits fourth signals to the at least one filter representing the determination of an actual value of a first one of the at least two parameters and/or of a second one of the at least two parameters,

receives fifth signals from said at least one filter representing the selection of the at least one of the coefficient of friction and the tire stiffness which corresponds to the values for the first one of the at least two parameters and/or of the second one of the at least two parameters based on said relationship, which at least one of the coefficient of friction and the tire stiffness is selected by the at least one filter as being the closest to the determined actual value of the first one of the at least two parameters and/or of the second one of the at least two parameters, respectively.

35. Method according to claim 33, wherein the control unit:

transmits sixth signals representing the at least one of the coefficient of friction and the tire stiffness to be determined to an assistance system of the vehicle for further processing.

36. Method for determining a coefficient of friction and/or a tire stiffness, the method comprising the steps of:

sensing a plurality of parameters related to a vehicle motion;

determining a data pair comprising a tire force and a tire slip in a tire force/tire slip space from said sensed plurality of parameters related to the vehicle motion;

segmenting the tire force/tire slip space into intervals which are defined for values of the tire force and the tire slip, wherein each of said intervals correlates to a data bin comprising previously stored estimates for at least the tire force and/or the tire slip, respectively;

selecting an interval which corresponds to said data pair;

continuously performing recursive updating of a data bin for said interval, said recursive updating being made from said data pair and said previously stored estimates of the tire force and/or the tire slip, respectively;

determining a relation between the tire force and the tire slip in the tire force/tire slip space on basis of said previously stored estimates of the tire force and/or the tire slip of said data bins in each interval, wherein said relation is expressed as a function of the tire stiffness and the coefficient of friction adapted to said stored estimates of the tire force and/or the tire slip of said data bins in each interval; and

determining the actual value for the coefficient of friction and/or for the tire stiffness from said function.

37. Method according to claim 36, wherein the step of updating said data bin includes the step of:

averaging over a previously stored estimate of the tire force and/or a previously stored estimate of the tire slip and a sensed actual value of the tire force or a sensed determined actual value of the tire slip from said data pair, respectively.

38. Method according to claim 36, further comprising the step of:

assessing the importance and/or assessing the confidence of the values of the stored estimates of the tire force and of the tire slip within said data bin.

39. Method according to claim 36, further comprising the steps of:

detecting a defined change in at least one of the tire force and the tire slip, or detecting a sudden change of the actual value for the coefficient of friction and/or for the tire stiffness; and

clearing and resetting said data bin.

40. Method according to claim 36, further comprising the steps of:

defining a grid for the coefficient of friction/tire stiffness space, single grid points of said grid correlating to predefined values of a coefficient of friction and a tire stiffness, which correspond to values for the tire force and/or the tire slip based on a relation between the tire force, the tire slip, the coefficient of friction and the tire stiffness;

selecting the grid point which corresponds to said updated data bins, for which a difference to said data pair is the smallest, respectively; and

determining the actual value for the coefficient of friction and/or the tire stiffness from said selected grid point.

41. Method according to claim 36, further comprising the steps of:

continuously applying corrective filtering procedures to said sensed parameters, and

updating the continuously corrected values in said data pairs.

42. Method according to claim 41, wherein a value of the rolling radius of the tire is corrected.

43. Method according to claim 36, wherein different steps are performed to determine the different parameters for the longitudinal direction and/or for the lateral direction of the tire.

44. Use of the method according to claim 36 in at least one assistance system of a vehicle.

45. Method for determining a coefficient of friction and/or a tire stiffness, the method comprising the steps of:

sensing a plurality of parameters related to a vehicle motion;

determining a data pair comprising a tire force and a tire slip from said sensed plurality of parameters related to the vehicle motion;

determining estimates for the tire force and/or the tire slip from said data pair based on a relation between the tire force, the tire slip, the coefficient of friction and the tire stiffness;

defining a grid for the coefficient of friction/tire stiffness space, single grid points of said grid correlating to predefined values of a coefficient of friction and a tire stiffness, which correspond to estimates for the tire force and/or the tire slip;

continuously performing recursive updating of said estimates for the tire force and/or the tire slip, said recursive updating being made from said data pair and said previously stored estimates of the tire force and/or the tire slip, respectively;

selecting the grid point which corresponds to said estimates for the tire force and/or the tire slip, for which the difference to said data pair is the smallest, respectively; and

determining the actual value for the coefficient of friction and/or the tire stiffness from said selected grid point.

46. Method according claim 45, wherein the step of updating is limited to a defined time frame.

47. Method according to claim 45, further comprising the steps of:

continuously applying corrective filtering procedures to said sensed parameters, and

updating the continuously corrected values in said data pairs.

48. Method according to claim 47, wherein a value of the rolling radius of the tire is corrected.

49. Method according to claim 45, wherein different steps are performed to determine the different parameters for the longitudinal direction and/or for the lateral direction of the tire.

50. Use of the method according to claim 45 in at least one assistance system of a vehicle.