Method of operating a motor vehicle

• US 6,834,221 B2
• Filed: 12/07/2001
• Issued: 12/21/2004
• Est. Priority Date: 06/08/1999
• Status: Expired due to Fees

• Current Assignee: Schaeffler Technologies AG & Co.KG (INA-Holding Schaeffler GmbH & Co. KG)
• Original Assignee: LuK Lamellen und Kupplungsbau Beteiligungs KG
• Inventors: Henneberger, Klaus, Zimmermann, Martin, Jäger, Thomas
• Primary Examiner(s): Nguyen, Thu V.
• Application Number:
  US10/012,694
• Publication Number:
  US 20020091472A1
• Time in Patent Office: 1,110 Days
• Field of Search: 701/34, 701/29, 701/74-75, 701/82-83, 701/90
• US Class Current: 701/34
• 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 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 8/173 Eliminating or reducing the effect of unwanted signals, e.g. due to vibrations or electrical noise
• CPC Class Codes: G01P 21/02 of speedometers

Abstract

The method is designed for a motor vehicle equipped with wheel rpm sensors and means to determine whether the wheels are either rolling normally or locked or spinning without adhesion. The method employs plausibility routines to determine whether an abnormal wheel rpm sensor signal is due to locking or spinning of the wheel or whether it is due to a sensor failure. In case that an abnormal condition is detected, an alternate strategy is initialized to determine wheel rpm rates and perform control functions that are based on wheel rpm rates.

Claims

1. A method of operating a motor vehicle with an engine, at least one drive axle with at least one wheel, the latter being in contact with a pavement surface, at least one torque transfer arranged in a power train between the engine and the at least one drive axle, and an automated transmission and at least one wheel rpm sensor device for detecting a wheel rpm rate of the at least one wheel;

the method comprising the steps of;

determining a transmission input rpm rate free of use of a transmission input rpm sensor and based on the at least one wheel rpm sensor and on a transmission ratio that is effective between the transmission output shaft and the transmission input shaft when a gear is engaged, wherein the transmission input rpm rate is determined by;

calculating a substitute wheel rpm rate according to a predetermined characteristic;

comparing the substitute wheel rpm rate to the detected wheel rpm rate; and

determining whether the detected wheel rpm rate is sufficiently reliable to use in calculating a transmission input-rpm rate; and

determining, based on the comparison between the substitute wheel rpm rate and the detected wheel rpm rate;

whether the wheel is rolling on the pavement surface;

whether the wheel is spinning while slipping on the pavement surface;

whether the wheel is locked;

whether the wheel rpm sensor device is functioning correctly; and

whether the wheel rpm sensor device is functioning incorrectly.

2. The method of claim 1, wherein the steps of determining whether the wheel is rotating on the pavement surface;

whether the wheel is spinning while slipping on the pavement surface; and

whether the wheel is locked include monitoring and evaluating at least a first characteristic operating value of the at least one wheel to determine whether the detected wheel rpm rate is an implausible rpm rate, an implausible rpm rate being a wheel rpm rate corresponding to one of the conditions where;

the wheel is not rolling while the motor vehicle is moving;

the wheel rpm rate is different from zero while the motor vehicle is standing still;

the wheel rpm rate is zero while the motor vehicle is moving;

the method further comprising a step of monitoring at least a second characteristic operating value of the motor vehicle and a second characteristic operating value of at least one wheel to determine

in case the wheel rpm rate was found implausible in a first step that includes monitoring and evaluating the first characteristic operating value, whether said wheel rpm rate remains implausible, and to further determine if and when said wheel rpm rate become plausible again;

in case the wheel rpm rate was found plausible in the first step, whether said wheel rpm rate remains plausible, and to further determine if and when said wheel rpm rate becomes implausible.

3. The method of claim 2, further comprising a third step wherein, if the wheel rpm rate was found implausible in at least one of the first step and a second step that includes monitoring and evaluating the second characteristic operating value, a determination is made

whether the wheel is spinning while slipping on the pavement surface;

whether the wheel is locked;

whether the wheel rpm sensor device is functioning incorrectly.

4. The method of claim 2, wherein the evaluating in the first step comprises calculating a substitute wheel rpm rate and comparing said substitute wheel rpm rate to said wheel rpm rate.

5. The method of claim 1, further including the steps of:

monitoring and evaluating at least one of the wheel rpm rate and a time gradient of the wheel rpm rate, and wherein determining whether the wheel rpm sensor device is functioning correctly includes at least one comparison of at least one of the wheel rpm rate and the rpm time gradient to at least one functional limit;

wherein said at least one functional limit has been determined according to a predetermined characteristic; and

wherein further said at least one functional limit represents at least one of a maximum and a minimum value which, based on the laws of physics, cannot be exceeded within a given time interval.

6. The method o claim 5, wherein said at least one functional limit comprises:

a functional maximum wheel rpm limit;

a functional minimum wheel rpm limit;

a functional maximum rpm time gradient limit;

a functional minimum rpm time gradient limit.

7. The method of claim 5, wherein the functional maximum rpm time gradient limit consists of an algebraically positive value and the functional minimum rpm time gradient limit consists of an algebraically negative value.

8. The method of claim 1, further including the steps of:

determining a time gradient of the wheel rpm rate and wherein determining whether the at least one wheel is rolling on the pavement surface includes comparing the time gradient of the wheel rpm rate to a maximum- and minimum rpm rolling-compatible time gradient;

wherein said wheel is determined as rolling if the time gradient of the wheel rpm rate is at the same time greater than the minimum, and less than the maximum rolling-compatible rpm time gradient.

9. The method of claim 8, wherein when the time gradient of the wheel rpm rate is greater than the maximum rolling-compatible rpm time gradient, the wheel rpm rate will meet the inequality v<

C×

n/60, and during at least part of a time period when the time gradient of the wheel rpm rate is less than the maximum rolling-compatible rpm time gradient, the wheel rpm rate will meet the equation v=C×

n/60 with v standing for a travel velocity the wheel, n standing for the rpm rate of the wheel, and C standing for an outer circumference of the wheel.

10. The method of claim 8, wherein when the time gradient of the wheel rpm rate is less than the minimum rolling-compatible rpm time gradient, the wheel rpm rate will meet the inequality v>

C×

n/60, and during at least part of a time period when the time gradient of the wheel rpm rate is greater than the minimum rolling-compatible rpm time gradient, the wheel rpm rate will meet the equation v=C×

n/60 with v standing for a travel velocity the wheel, n standing for the rpm rate of the wheel, and C standing for an outer circumference of the wheel.

11. The method of claim 8, wherein said wheel is determined as rolling if an additional predetermined condition is met.

12. The method of claim 11, wherein the additional predetermined condition comprises that in a last previous cycle of the method, said wheel was determined to be rolling.

13. The method of claim 8, wherein the maximum rolling-compatible rpm time gradient consists of an algebraically positive value and the minimum rolling-compatible rpm time gradient consists of an algebraically negative value.

14. The method of claim 8, wherein the maximum rolling-compatible rpm time gradient is determined based on a current engine torque and based on a current rpm transfer ratio between the engine and the at least one wheel.

15. The method of claim 8, wherein the motor vehicle comprises a service brake device and wherein the minimum rolling-compatible rpm time gradient is based on a maximum brake torque that the service brake device can apply to the at least one wheel.

16. The method of claim 15, wherein the minimum rolling-compatible rpm time gradient is further based on a predetermined coefficient of friction between the at least one wheel and the pavement surface.

17. The method of claim 8, wherein at least one of the maximum and minimum rolling-compatible rpm time gradients is determined based on at least one characteristic value of the motor vehicle.

18. The method of claim 8, wherein at least one of the maximum and minimum rolling-compatible rpm time gradients is determined based on an inertial force by which at least one element of the power train opposes a motion of the at least one wheel.

19. The method of claim 18, wherein at least one of the maximum and minimum rolling-compatible rpm time gradients is determined based on a transmission ratio that is selectable by shifting at least one transmission device arranged in the power train.

20. The method of claim 8, wherein at least one of the maximum and minimum rolling-compatible rpm time gradients is determined based on an engagement position of at least one clutch device arranged in the power train.

21. The method of claim 8, wherein at least one of the maximum and minimum rolling-compatible rpm time gradients is determined based on a current level of drive power delivered by the engine substantially at the time when said at least one of the maximum and minimum rolling-compatible rpm time gradients is being determined.

22. The method of claim 8, wherein at least one of the maximum and minimum rolling-compatible rpm time gradients is determined based on a maximum level of drive power that the engine is capable of delivering.

23. The method of claim 8, wherein at least one of the maximum and minimum rolling-compatible rpm time gradients is determined based on a current characteristic operating value of the vehicle, said operating value being applicable substantially at the time when said at least one of the maximum and minimum rolling-compatible rpm time gradients is being determined.

24. The method of claim 23, wherein at least one of the maximum and minimum rolling-compatible rpm gradients depends on at least one characteristic operating value of the vehicle in whose presence the wheel rpm gradient limit reaches a predetermined extreme.

25. The method of claim 8, wherein at least one of the maximum and minimum rolling-compatible rpm time gradients is substantially independent of at least one current characteristic operating value of the vehicle while being dependent on a potential characteristic operating value of the vehicle, said potential value being applicable under predetermined conditions that can occur during operation of the vehicle.

26. The method of claim 8, wherein a wheel rpm time gradient is admitted into the comparison only if it was determined in a time interval when the wheel rpm rate changed monotonically from a first wheel rpm rate to a second wheel rpm rate and the difference between said first and second wheel rpm rate exceeded a predetermined threshold difference.

27. The method of claim 8, wherein if the wheel has been determined as not rolling and until the wheel has been determined as rolling again, a substitute wheel rpm rate is used for at least one of the purposes of operating the motor vehicle, determining whether the at least one wheel is rolling, and determining whether the wheel rpm sensor device is functioning correctly.

28. The method of claim 27, wherein the substitute wheel rpm rate is kept constant for a length of time while the substitute wheel rpm rate is being used.

29. The method of claim 27, wherein as long as the substitute wheel rpm rate is in use, the substitute wheel rpm rate is incrementally changed according to a predetermined characteristic.

30. The method of claim 29, wherein said incremental changes are made in an increasing sense if the substitute wheel rpm rate is less than the wheel rpm rate, and in a decreasing sense if the substitute wheel rpm rate is more than the wheel rpm rate.

31. The method of claim 27, wherein the substitute wheel rpm rate is set to a predetermined starting value if the at least one wheel was determined as not rolling.

32. The method of claim 31, wherein the starting value depends on a last previously determined wheel rpm rate that was found to be plausible.

33. The method of claim 27, wherein a rotary state of the at least one wheel is determined by using at least one of the wheel rpm rate detected by the sensor device and a substitute wheel rpm rate, and wherein the rotary state comprises at least one of the states where the wheel is rolling on the pavement surface;

the wheel is not rolling on the pavement surface;

the wheel is spinning while slipping on the pavement surface;

the wheel is locked;

the wheel rpm sensor device is functioning incorrectly.

34. The method of claim 33, wherein a determination that the wheel is spinning while slipping on the pavement surface can occur only if at a time of determining the wheel rpm rate, the engine delivers an engine torque greater than zero.

35. The method of claim 33, wherein a determination that the wheel is locked can occur only if at a time of determining the wheel rpm rate, a service brake device of the motor vehicle is being actuated.

36. The method of claim 27, wherein a new substitute wheel rpm rate is determined based on a plausible starting rpm rate, the latter comprising one of a wheel rpm rate, a substitute starting rpm rate and a last previous substitute wheel rpm rate presumed to be plausible, and wherein the new substitute wheel rpm rate depends on at least one of the maximum and minimum rolling-compatible as well as functional rpm time gradient limits.

37. The method of claim 36, wherein the new substitute wheel rpm rate is presumed to be plausible.

38. The method of claim 36, wherein the new substitute wheel rpm rate is determined by calculating a product of a predetermined wheel rpm gradient limit and a length of a predetermined time interval and then calculating a sum of said product and said plausible starting rpm rate, wherein the plausible starting rpm rate is assumed to have been plausible at least at a starting point of said predetermined time interval.

39. The method of claim 38, wherein the new substitute wheel rpm rate is determined by further adding an offset value to said sum, wherein the offset value is of a substantially constant magnitude corresponding substantially to one-half of a noise amplitude of the wheel rpm rate, the offset value being algebraically positive if the predetermined wheel rpm gradient limit in said product represents an upper limit, and algebraically negative if the predetermined wheel rpm gradient limit in said product represents a lower limit.

40. The method of claim 38, wherein the new substitute wheel rpm rate is compared to the wheel rpm rate detected at the end of the predetermined time interval, and wherein based on said comparison a determination is made whether the wheel is rolling on the pavement surface;

whether the wheel is spinning while slipping on the pavement surface;

whether the wheel is locked;

whether the wheel rpm sensor device is functioning correctly;

whether the wheel rpm sensor device is functioning incorrectly.

41. The method of claim 40, wherein the method is repeated in continuous cycles in order to continuously monitor the wheel by making said comparison and determination.

42. The method of claim 41, wherein the method comprises determining within each cycle of the method a plurality of new substitute wheel rpm rates based on a plurality of different wheel rpm gradient limits and to make said comparison and determination individually for each of said new substitute wheel rpm rates.

43. The method of claim 41, wherein a result of said determination is accepted after said result has not changed over a predetermined consecutive number of said continuous cycles.

44. The method of claim 8, wherein the time gradients of the wheel rpm rate are determined based on the detected wheel rpm rate.

45. The method of claim 8, wherein the motor vehicle is operated under a control based on the wheel rpm rate.

46. The method of claim 8, wherein at least one characteristic operating value of the motor vehicle is determined based on the wheel rpm rate.

47. The method of claim 8, further comprising a third step in which a traveling speed of the motor vehicle is determined based on the wheel rpm rate.

48. The method of claim 8, wherein the time gradients of the wheel rpm rate are determined as mean time gradients over a predetermined time interval.

49. A method of claim 1, wherein the engine includes a starter motor and a battery and wherein the torque transfer system comprises at least one transmission device and wherein the wheel rpm sensor device comprises an electrical control device, the method further comprising the step of keeping information available concerning at least one signal of relevance for the safety of the vehicle after a reset of the control device has occurred.

50. The method of claim 49, wherein said information concerns an error condition.

51. The method of claim 49, further comprising the step of keeping information available concerning at least one further signal of relevance for the safety of the vehicle after a reset of the control device has occurred.

52. The method of claim 49, wherein said information concerns a currently set ratio of the transmission device.

53. The method of claim 49, wherein said information is stored in a non-volatile memory device.

54. The method of claim 53, wherein the non-volatile memory device is an EEPROM.

55. The method of claim 53, wherein said information is stored at one of the times before and during a critical situation.

56. The method of claim 53, wherein said information is stored before enabling current to flow through the starter motor.

57. The method of claim 53, wherein said information is stored after a finding that the battery is not being charged properly.

58. The method of claim 53, wherein said information is stored when the motor vehicle is standing still.

59. The method of claim 53, wherein said information is retrieved from the non-volatile memory after the reset of the control device.

60. The method of claim 59, wherein the non-volatile memory comprises at least one memory location containing at least a flag indicating whether the information was stored completely and without error.

61. The method of claim 60, wherein said information is retrieved only if said flag indicates that the information was stored completely and without error.

62. The method of claim 60, wherein said information is generated anew if said flag indicates that the information was not stored completely and without error.

63. A method of operating a motor vehicle with an engine, at least one drive axle with at least one wheel, the latter being in contact with a pavement surface, at least one torque transfer system arranged in a power train between the engine and the at least one drive axle, and an automated transmission and a wheel rpm sensor device for detecting a wheel rpm rate of the at least one wheel;

the method comprising the step of determining a transmission input rpm rate free of use of a transmission input rpm sensor by determining the transmission input rpm rate based on the at least one wheel sensor and based on a transmission ratio that is effective between the transmission output shaft and the transmission input shaft when a gear is engaged, and wherein the transmission input rpm rate is determined by performing;

a first step to determine whether the at least one wheel is rolling at a time when at least one of the conditions applies that the motor vehicle is moving and the gas pedal is being applied;

the method further comprising a second step that is carried out if the wheel was found to be not rolling, said second step comprising calculating a substitute wheel rpm rate according to a predetermined characteristic and using said substitute wheel rpm rate for at least one of the purposes of operating the motor vehicle, determining whether the at least one wheel is rolling, and determining whether the wheel rpm sensor device is functioning correctly.

64. The method of claim 63, wherein the determination in the first step comprises determining time gradients of a wheel rpm rate.

65. A method of operating a motor vehicle with an engine, at least one drive axle with at least one wheel, the latter being in contact with a pavement surface, at least one torque transfer arranged in a power train between the engine and the at least one drive axle, and an automated transmission and at least one wheel rpm sensor device for detecting a wheel rpm rate of the at least one wheel;

the method comprising the steps of;

determining a transmission input rpm rate free of use of a transmission input rpm sensor by determining the transmission input rpm rate based on the at least one wheel sensor and based on a transmission ratio that is effective between the transmission output shaft and the transmission input shaft when a gear is engaged, and wherein the transmission input rpm rate is determined by evaluating;

whether the wheel is rolling on the pavement surface;

whether the wheel is spinning while slipping on the pavement surface;

whether the wheel is locked;

whether the wheel rpm sensor device is functioning correctly; and

whether the wheel rpm sensor device is functioning incorrectly.