Method for estimating vehicular running state, vehicular running state estimating device, vehicle control device, and tire wheel

• US 7,032,436 B2
• Filed: 06/21/2001
• Issued: 04/25/2006
• Est. Priority Date: 06/23/2000
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Bridgestone (Bridgestone Corporation)
• Original Assignee: Kabushiki Kaisha Bridgestone (Bridgestone Corporation)
• Inventors: Yokota, Hidetoshi, Morinaga, Hiroshi, Otani, Koji
• Primary Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US10/049,509
• Publication Number:
  US 20020162389A1
• Time in Patent Office: 1,769 Days
• Field of Search: 731/05, 73/7, 73/8, 73/9, 73/110.4, 73/110.5, 73/110.7, 73/110.8, 73/110.9, 731/04, 731/181
• US Class Current: 73/105
• CPC Class Codes: B60C 23/06 Signalling devices actuated by deformation of the tyre , e.g. tyre mounted deformation sensors or indirect determination of tyre deformation based on wheel speed, wheel-centre to ground distance or inclination of wheel axle
• CPC Class Codes: B60C 23/065 by monitoring vibrations in tyres or suspensions B60C23/062 takes precedence
• CPC Class Codes: B60G 17/0165 to an external condition, e.g. rough road surface, side wind
• CPC Class Codes: B60G 17/019 characterised by the type of sensor or the arrangement thereof B60G17/01941 takes precedence
• CPC Class Codes: B60G 17/0195 characterised by the regulation being combined with other vehicle control systems conjoint control of vehicle sub-units including control of suspension systems B60W10/22
• CPC Class Codes: B60G 2204/11 Mounting of sensors thereon
• CPC Class Codes: B60G 2204/113 Tyre related sensors
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/206 Body oscillation speed; Body vibration frequency
• CPC Class Codes: B60G 2400/208 of wheel rotation
• CPC Class Codes: B60G 2400/52 in tyre
• CPC Class Codes: B60G 2400/821 Uneven, rough road sensing affecting vehicle body vibration
• CPC Class Codes: B60G 2400/91 Frequency
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/188 Spectral analysis; Transformations
• CPC Class Codes: B60G 2600/60 Signal noise suppression; Electronic filtering means
• CPC Class Codes: B60G 2600/604 low pass
• CPC Class Codes: B60G 2800/162 Reducing road induced vibrations
• CPC Class Codes: B60G 2800/70 Estimating or calculating vehicle parameters or state variables
• CPC Class Codes: B60G 2800/702 : Improving accuracy of a sensor signal
• CPC Class Codes: B60G 2800/916 : Body Vibration Control
• CPC Class Codes: B60T 2210/12 : Friction
• CPC Class Codes: B60T 2210/13 : Aquaplaning, hydroplaning
• 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: G01H 1/003 : of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01H 1/12 : of longitudinal or not specified vibrations
• CPC Class Codes: G01H 1/14 : Frequency
• 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
• CPC Class Codes: G01N 2203/0676 : Force, weight, load, energy, speed or acceleration
• CPC Class Codes: G01N 2203/0682 : Spatial dimension, e.g. length, area, angle
• CPC Class Codes: G01N 2203/0688 : Time or frequency
• CPC Class Codes: G01N 9/24 : by observing the transmission of wave or particle radiation through the material

Abstract

The output level of vibration of a portion below the spring of a vehicle detected by a sensor, and its frequency is converted to obtain the frequency spectrum of the vibration level. Next, an operation is carried out on at least two vibration levels, at different frequency bands. The computed value is compared with a master curve showing the frequency spectrum of vibration level stored in vibration level storage to estimate the condition of a road surface so as to estimate the running state of the vehicle. Further, the running state of each tire including air pressure is detected from the vibration level of the portion below the spring to estimate the running state of the vehicle. Thereby, a multi-function sensing system is constructed for estimating the condition of a road surface or the running state of the tire with one sensor.

Claims

1. A vehicle running state estimation method comprising:

detecting a vibration level of a portion below a spring of a running vehicle; and

estimating the running state of the vehicle by determining at least one of a condition of a road surface on which the vehicle is running and a running state of each tire,

wherein said determining is based on the detected vibration level, and wherein a waveform of time changes in the vibration level is detected and the condition of the road surface on which the vehicle is running is estimated from a vibration level at a predetermined position of the waveform or for a predetermined time range.

2. A vehicle running state estimation method comprising:

detecting a vibration level of a portion below a spring of a running vehicle;

a frequency of the detected vibration level is analyzed to calculate a vibration level at a predetermined frequency band and a condition of the road surface on which the vehicle is running is estimated by comparing the calculated vibration level with a master curve which is a vibration level detected through running on a road having a predetermined condition of a road surface of the running vehicle.

3. The vehicle running state estimation method according to claim 2, wherein the master curve is prepared based on the vibration level detected at the time when the vehicle is running on a surface of a road with a usual dry asphalt pavement.

4. A vehicle running state estimation method comprising;

detecting a vibration level of a portion below a spring of a running vehicle; and

estimating the running state of the vehicle by determining a degree of slipperiness of a road surface on which the vehicle is running and a running state of each tire,

wherein said determining is based on the detected vibration level, and

wherein the frequency of the detected vibration level is analyzed, at least two vibration levels at different frequency bands are calculated, an operation is carried out on the at least two calculated vibration levels, and the degree of slipperiness of the road surface is estimated from computed value.

5. A vehicle running state estimation method comprising:

detecting a vibration level of a portion below a spring of a running vehicle; and

estimating the running state of the vehicle by determining a condition of a road surface on which the vehicle is running and a running state of each tire,

wherein said determining is based on the detected vibration level, and,

wherein vibration levels of at least two points of a portion below the spring with a buffer member interposed therebetween are detected to calculate a vibration transmission level of the portion below the spring between the two points at a predetermined frequency band; and

the condition of the road surface is estimated from the calculated vibration transmission level.

6. A vehicle running state estimation apparatus comprising:

means of detecting a vibration level of a portion below a spring of a running vehicle;

means of calculating a vibration level at a predetermined frequency band by analyzing frequency of the detected vibration level; and

road surface condition estimation means for estimating a condition of the road surface on which the vehicle is running by comparing the calculated vibration level with the master curve which is the vibration level detected through running on a road having a predetermined road surface condition,

wherein the running state of the vehicle is estimated based on the condition of the road surface from the road surface condition estimation means.

7. The vehicle state estimation apparatus according to claim 6, wherein the master curve is prepared based on the vibration level detected through the running on the surface of a usual road with dry asphalt pavement.

8. A vehicle running state estimation apparatus comprising:

means of detecting a vibration level of a portion below a spring of a running vehicle; and

road surface condition estimation means for estimating a degree of slipperiness of a road surface from a value obtained by carrying out an operation on at least two vibration levels at different frequency bands by analyzing the frequency of the detected vibration level,

wherein the running state of the vehicle is estimated based on the degree of slipperiness of the road surface received from the road surface condition estimation means.

9. A vehicle running state estimation apparatus for estimating a running state of a vehicle based on a condition of a road surface comprising:

means of detecting vibration levels of at least two points on a portion below a spring of the running vehicle with a buffer member being interposed therebetween;

means of calculating a vibration transmission level at a predetermined frequency band between said at least two vibration detection points; and

road surface condition estimation means for estimating a condition of the road surface on which the vehicle is running from the calculated vibration transmission level.

10. A vehicle running state estimation apparatus comprising:

means of detecting a vibration level of a portion below a spring of a running vehicle;

means of calculating a vibration level at a predetermined frequency band by analyzing frequency of the detected vibration level; and

road surface condition estimation means for estimating a degree of slipperiness of the road surface on which the vehicle is running from the calculated vibration level,

wherein the running state of the vehicle is estimated based on the degree of slipperiness of the road surface received from the road surface condition estimation means, and

wherein a road surface friction coefficient μ

at a time of running the vehicle is estimated based on a relationship between a surface friction coefficient μ

obtained from braking distances of the vehicle under various road conditions at different speeds and at least one of the calculated vibration level at said predetermined frequency band and a calculated vibration transmission level.

11. A vehicle running state estimation apparatus comprising;

means of detecting a vibration level of a portion below a spring of a running vehicle;

means of calculating a vibration level at a predetermined frequency band by analyzing frequency of the detected vibration level; and

road surface condition estimation means for estimating a degree of slipperiness of the road surface on which the vehicle is running from the calculated vibration level,

wherein the running state of the vehicle is estimated based on the degree of slipperiness of the road surface received from the road surface condition estimation means, and

wherein the frequency band is a band including frequency of natural vibration of a tire tread land portion.

12. A vehicle running state estimation apparatus comprising:

means of detecting a vibration level of a portion below a spring of a running vehicle;

means of calculating a vibration level at a predetermined frequency band by analyzing frequency of the detected vibration level; and

road surface condition estimation means for estimating a degree of slipperiness of the road surface on which the vehicle is running from the calculated vibration level,

wherein the running state of the vehicle is estimated based on the degree of slipperiness of the road surface received from the road surface condition estimation means, and

wherein a threshold value is set for the vibration level, and the surface of the road is estimated to be in a low friction condition when the calculated vibration level exceeds the threshold value.

13. The vehicle running state estimation apparatus according to claim 12, wherein the threshold value can be changed.

14. A vehicle running state estimation apparatus for estimating running state of a vehicle based on road surface conditions, the estimation apparatus comprising:

means of detecting a vibration level of a portion below a spring of a running vehicle;

means of computing waveform of time changes in the vibration level; and

road surface condition estimation means for estimating a condition of a road surface on which the vehicle is running from the vibration level at a predetermined position of the waveform or for a predetermined time range.

15. The vehicle running state estimation apparatus according to claim 14 further comprising means of calculating the vibration level of at least one of a tire leading edge portion, tire ground contact portion and tire trailing edge portion of the waveform.

16. The vehicle running state estimation apparatus according to claim 14 which further comprises a vehicle speed detection means to estimate the condition of a road surface based on vehicle speed.

17. The vehicle running state estimation apparatus of claim 14, further comprising:

means of judging slipperiness of the road surface based on the condition of the road surface estimated by the road surface condition estimation means; and

warning means for giving a warning when it is judged that the condition of the road surface is slippery.

18. The vehicle running state estimation apparatus according to claim 17, further comprising:

vehicle speed detection means to change decision on the slipperiness of the road surface and warning level based on vehicle speed.

19. The vehicle running state estimation apparatus according to claim 14, further comprising a transmitter for transmitting output of the vibration detection means for calculating a time change in the vibration level or a vibration level at a predetermined frequency band.

20. The vehicle running state estimation apparatus according to claim 14 further comprising a power generating unit mounted on a tire wheel, wherein the power generating unit generates power by rolling of each tire and supplies power for at least one of driving the vibration detection means and amplifying output of the vibration detection means.

21. A vehicle control apparatus comprising vehicle control means for controlling the running state of a vehicle based on the condition of the road surface estimated by the vehicle running state estimation apparatus of claim 14.

22. The vehicle control apparatus according to claim 21 which comprises vehicle speed detection means to control the running state of the vehicle based on vehicle speed.

23. The vehicle control apparatus according to claim 21, wherein the vehicle control means controls locked state of each wheel.

24. The vehicle control apparatus according to claim 21, wherein the vehicle control means controls attitude of the vehicle.

25. The vehicle control apparatus according to claim 21, wherein the vehicle control means controls air pressure of each tire.

26. The vehicle control apparatus according to claim 21, wherein the vehicle control means controls idling state of each wheel.

27. The vehicle control apparatus according to claim 21, wherein the vehicle control means changes inter-vehicle distance set value of an automatic driving system.

28. A tire wheel comprising:

the vehicle running state estimation apparatus for estimating a running state of the vehicle by detecting the vibration level of the portion below the spring as set forth in claim 14, and a power generating unit for generating power by a rolling of each tire and supplying power to the estimation apparatus.

29. The tire wheel according to claim 28, wherein the vehicle running state estimation apparatus is mounted to the tire wheel.

30. The tire wheel according to claim 28, wherein the power generating unit comprises a rotor magnetized and rotated by the rolling of each tire, a stator made from a high magnetic permeability material and adjacent to the rotor and a power generating coil installed within a magnetic circuit including the rotor and the stator.

31. The tire wheel according to claim 30, wherein the power generating unit comprises means of accumulating electromotive force generated in the power generating coil.

32. The tire wheel according to claim 30, wherein the rotor is turned by rotating an unbalance weight the gravity center of the rotary cone of which is eccentric to a rotary shaft by the rolling of each tire.

33. The tire wheel according to claim 30, wherein an air stream generated by the rolling of each tire is introduced into the power generating unit and the rotor is turned by the introduced air stream.