Road surface state estimating apparatus, road surface friction state estimating apparatus, road surface state physical quantity calculating apparatus, and road surface state announcing apparatus

• US 20040138831A1
• Filed: 11/07/2003
• Published: 07/15/2004
• Est. Priority Date: 11/08/2002
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Original Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Inventors: Asami, Shu, Umeno, Takaji, Asano, Katsuhiro, Watanabe, Yoshitoshi, Sugai, Masaru
• Granted Patent: US 7,248,958 B2
• Time in Patent Office: Days
• US Class Current: 702/33
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 8/1725 Using tyre sensors, e.g. Sidewall Torsion sensors [SWT] for tyre pressure and temperature detection B60C23/00
• CPC Class Codes: B60W 2420/54 Audio sensitive means, e.g. ultrasound
• CPC Class Codes: B60W 40/068 Road friction coefficient

Abstract

A tire-generated sound detection sensor detects a tire-generated sound that is generated from a tire while the vehicle is running. A wheel rotation sensor detects a wheel rotation speed. A preprocessor calculates feature quantities corresponding to a road surface state and tire-generated sound sources. A feature vector generator generates a feature vector having, as components, the feature quantities calculated by the preprocessor and the detected wheel rotation speed. A judgment processor estimates a state of a road surface on which the vehicle is running on the basis of the feature vector generated by the feature vector generator and feature vectors that are stored in a judgment map memory so as to be correlated with a plurality of road surface states, respectively, and each of which corresponds to a road surface state and tire-generated sound sources.

Claims

1. A road surface state estimating apparatus comprising

a tire-generated sound detector for detecting a tire-generated sound that is generated from a tire while a vehicle is running;

a calculator for calculating at least one feature quantity corresponding to a road surface state and tire-generated sound sources from the tire-generated sound detected by the tire-generated sound detector;

a storage device for storing feature quantities, each quantity corresponding to a road surface state and tire-generated sound source, in such a manner that the feature quantities are correlated with a plurality of road surface states, respectively; and

an estimating device for estimating a state of a road surface on which the vehicle is running on the basis of the feature quantity calculated by the calculator and the feature quantities stored in the storage device.

2. The road surface state estimating apparatus according to claim 1, further comprising:

a wheel rotation speed detector for detecting a wheel rotation speed, wherein

the storage device stores the feature quantities in such a manner that the feature quantities are correlated with respective each of a plurality road surface states and each of a plurality of wheel rotation speeds; and

the estimating device estimates a state of a road surface on which the vehicle is running on the basis of the feature quantity calculated by the calculator, the wheel rotation speed detected by the wheel rotation speed detector, and the feature quantities stored in the storage device.

3. The road surface state estimating apparatus according to claim 1, wherein the calculator calculates at least one feature quantity corresponding to a road surface state and tire-generated sound source by calculating correlation values of a waveform of the tire-generated sound detected by the tire-generated sound detector and at least one fundamental waveform having a predetermined length.

4. The road surface state estimating apparatus according to claim 1, wherein the calculator uses wavelet transform.

5. The road surface state estimating apparatus according to claim 1, wherein the calculator calculates correlation values of a waveform of the tire-generated sound detected by the tire-generated sound detector and at least one wavelet fundamental waveform.

6. The road surface state estimating apparatus according to claim 3, wherein the fundamental waveform has two first regions in which an amplitude of the wave is within a first range and a second region that is interposed between the two first regions and in which an amplitude of the wave is larger than in the two first regions and the value is within a second range that is wider than the first range.

7. The road surface state estimating apparatus according to claim 3, wherein the calculator calculates correlation values of a waveform of the tire-generated sound detected by the tire-generated sound detector and a fundamental waveforms corresponding to at least one road surface state.

8. The road surface state estimating apparatus according to claim 7, wherein the calculator sets the fundamental waveforms by modifying a predetermined original waveform so that it becomes suitable for the road surface states.

12. The road surface friction state estimating apparatus according to claim 11, wherein the detector is the road surface state estimating apparatus according to claim 1.

20. The road surface state estimating apparatus according to claim 18, further comprising:

the road surface state estimating apparatus according to claim 1;

and

an updating device for updating the road surface state physical quantity that is stored in the storage device and corresponds to the road surface state estimated by the road surface state estimating apparatus, on the basis of the road surface state estimated by the road surface state estimating apparatus and at least one of saturation information, luminance information, hue information, and intensity information that was detected by the detector when the road surface state estimating apparatus estimated the road surface state.

9. A road surface friction state estimating apparatus comprising:

a detector for detecting a feature quantity indicating a road surface state;

a storage device for storing road surface friction states that are friction states between road surfaces and a tire in such a manner that the road surface friction states are correlated with a plurality of feature quantities indicating different road surface states, respectively;

an estimating device for estimating a road surface friction state of the road surface, the road surface corresponding to the feature quantity which is detected by the detector, on the basis of the feature quantities detected by the detector and the road surface friction states stored in the storage device; and

a corrector for correcting a road surface friction state stored in the storage device on the basis of a pre-detected road surface friction state of the road surface, the road surface corresponding to the feature quantity which is detected by the detector, and the road surface friction state estimated by the estimating device.

10. The road surface friction state estimating apparatus according to claim 9, wherein the detector detects a feature quantity indicating a road surface state of a forward road surface.

11. The road surface friction state estimating apparatus according to claim 9, wherein the detector detects feature quantity indicating a road surface state of a road surface on which a vehicle is running.

13. A road surface friction state estimating apparatus comprising:

a first detector for detecting feature quantity indicating a road surface state of a road surface on which a vehicle is running;

a second detector for detecting a feature quantity indicating a road surface state of a forward road surface;

a synchronizer for synchronizing a feature quantity detected by the second detector with the feature quantities detected by the first detector of a road surface, the road surface corresponding to the feature quantity which was detected by the second detector;

a storage device for storing road surface friction states that are friction states between road surfaces and a tire in such a manner that the road surface friction states are correlated with a plurality of feature quantities indicating different road surface states, respectively; and

an estimating device for estimating a road surface friction state of the road surface, the road surface corresponding to the feature quantity which is detected by the first detector, on the basis of the feature quantity detected by the first detector, the feature quantity detected by the second detector and synchronized by the synchronizer, and the road surface friction states stored in the storage device.

14. The road surface friction state estimating apparatus according to claim 13, further comprising a corrector for correcting a road surface friction state stored in the storage device on the basis of a road surface friction state of the road surface, the road surface corresponding to feature quantity which is detected by the first detector and the road surface friction state estimated by the estimating device.

15. A road surface state physical quantity calculating apparatus comprising:

a detector for detecting at least one of saturation information, luminance information, hue information, and intensity information of a forward road surface on which a vehicle will run; and

a calculator for calculating a road surface state physical quantity on the basis of at least one of saturation information, luminance information, hue information, and intensity information of the forward road surface detected by the detector and a parameter to be used for calculating a road surface state physical quantity indicating a road surface state,

wherein the calculator corrects the parameter on the basis of at least one of saturation information, luminance information, hue information, and intensity information of the forward road surface detected by the detector, and calculates a road surface state physical quantity indicating a road surface state on the basis of the corrected parameter and at least one of saturation information, luminance information, hue information, and intensity information of the forward road surface detected by the detector.

16. The road surface state physical quantity calculating apparatus according to claim 15, wherein:

the detector divides an area of the forward road surface into a plurality of regions and detects pieces of at least one of saturation information, luminance information, hue information, and intensity information of the respective regions;

the parameter is a value to be used for classifying the detected pieces of at least one of saturation information, luminance information, hue information, and intensity information of the respective regions into classes corresponding to respective road surface states; and

the calculator calculates a road surface state physical quantity by classifying the detected pieces of at least one of saturation information, luminance information, hue information, and intensity information of the respective regions into the classes corresponding to the respective road surface states using the parameter.

17. The road surface state physical quantity calculating apparatus according to claim 15, wherein:

the detector divides an area of the forward road surface into a plurality of regions and detects pieces of at least one of saturation information, luminance information, hue information, and intensity information of the respective regions;

the parameter is a value that maximizes a probability that the detected pieces of at least one of saturation information, luminance information, hue information, and intensity information of the respective regions are obtained; and

the calculator calculates a road surface state physical quantity by calculating a probability maximized by the parameter.

18. A road surface state estimating apparatus comprising:

a storage device for storing road surface state physical quantities determined on the basis of at least one of saturation information, luminance information, hue information, and intensity information and indicating road surface states of a plurality of road surfaces, respectively, in such a manner that the road surface state physical quantities are correlated with the respective road surface states;

a detector for detecting at least one of saturation information, luminance information, hue information, and intensity information of a forward road surface; and

an estimating device for estimating a road surface state of the forward road surface on the basis of at least one of saturation information, luminance information, hue information, and intensity information of the forward road surface detected by the detector and the road surface state physical quantities stored in the storage device.

19. The road surface state estimating apparatus according to claim 18, wherein the estimating device determines a road surface state physical quantity on the basis of at least one of saturation information, luminance information, hue information, and intensity information of the forward road surface detected by the detector, and estimates a road surface state of the forward road surface on the basis of the determined road surface state physical quantity and the road surface state physical quantities stored in the storage device.

21. A road surface state announcing apparatus comprising:

a current road surface state detector for detecting a road surface state of a current road surface on which a vehicle mounted is running;

a forward road surface state detector for detecting a road surface state of a forward road surface; and

an announcing device for comparing the road surface state of the current road surface detected by the current road surface ill state detector and the road surface state of the forward road surface detected by the forward road surface state detector, and for making an announcement about a post-variation road surface state if one of the road surface state of the current road surface and the road surface state of the forward road surface has varied.

22. The road surface state announcing apparatus according to claim 21, wherein the announcing device makes an announcement about a post-variation road surface state of the forward road surface if the road surface state of the current road surface has changed after the road surface state of the forward road surface changed from the road surface state of the current road surface.

23. A road surface state announcing apparatus comprising:

a current road surface state detector for detecting a road surface state of a current road surface on which a vehicle is running;

a forward road surface state detector for detecting a road surface state of a forward road surface;

a synchronizer for synchronizing a road surface state of a forward road surface detected by the forward road surface state detector with the road surface state of the current road surface detected by the current road surface state detector; and

an announcing device for making an announcement about a road surface state of the current road surface on the basis of the road surface state of the current road surface detected by the current road surface state detector and the road surface state of the forward road surface detected by the forward road surface state detector and synchronized by the synchronizer with the road surface state of the current road surface detected by the current road surface state detector.

24. A road surface friction state estimating apparatus comprising:

a road surface state detector for detecting a road surface state of a road surface on which a vehicle in running;

a road surface friction state estimating device for estimating a road surface friction state as a friction state between the road surface and a tire of the vehicle; and

a final road surface friction state estimating device for estimating a final road surface friction state on the basis of the road surface state detected by the road surface state detector and the road surface friction state estimated by the road surface friction state estimating device.

25. The road surface friction state estimating apparatus according to claim 24, wherein road surface friction state ranges are set in advance so as to be correlated with a plurality of road surface states, respectively, the road surface friction state estimating apparatus further comprising:

a judging component for judging whether the road surface friction state detected by the road surface friction state estimating device falls within a road surface friction state range corresponding to the road surface state detected by the road surface state detector on the basis of the road surface friction state ranges corresponding to the respective road surface states, the road surface state detected by the road surface state detector, and the road surface friction state detected by the road surface friction state estimating device, wherein

the final road surface friction state estimating device for estimating a final road surface friction state on the basis of the road surface state detected by the road surface state detector and the road surface friction state estimated by the road surface friction state estimating device and judged to be within the road surface friction state range corresponding to the road surface state, if the judging component judges that the road surface friction state detected by the road surface friction state estimating device falls within the road surface friction state range corresponding to the road surface state detected by the road surface state detector.

26. A road surface state estimating apparatus comprising:

a tire-generated sound detector for detecting a tire-generated sound that is generated from a tire while a vehicle is running;

a wheel rotation speed detector for detecting a wheel rotation speed;

a storage device for storing a relationships between feature quantities corresponding to tire-generated sound sources and a wheel rotation speed in such a manner that the sets of coefficients are correlated with a plurality of road surface states, respectively; and

an estimating device for estimating a road surface state on the basis of the tire-generated sound detected by the tire-generated sound detector, the wheel rotation speed detected by the wheel rotation speed detector, and the coefficients stored in the storage device.

27. The road surface state estimating apparatus according to claim 26, further comprising:

an updating device for updating the relationship stored in the storage device on the basis of the tire-generated sound detected by the tire-generated sound detector and the wheel rotation speed detected by the wheel rotation speed detector, wherein

the estimating device estimates a road surface state on the basis of the tire-generated sound detected by the tire-generated sound detector, the wheel rotation speed detected by the wheel rotation speed detector, and the relationship stored in the storage device and updated by the updating device.