Tire parameter estimation device and road surface judgment device

• US 20020010537A1
• Filed: 04/03/2001
• Published: 01/24/2002
• Est. Priority Date: 04/05/2000
• Status: Active Grant

• Current Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.), Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Inventors: Tanaka, Akira, Sugiura, Noboru, Asano, Katsuhiro, Sawada, Mamoru, Watanabe, Yoshitoshi, Yamaguchi, Hiroyuki, Amano, Yasushi, Yasui, Yoshiyuki, Miyashita, Masanori
• Granted Patent: US 6,704,636 B2
• Time in Patent Office: Days
• US Class Current: 701/80
• CPC Class Codes: B60C 11/246 Tread wear monitoring systems
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• 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: G01K 7/42 Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature

Abstract

A tire parameter estimation device that is economical and can accurately estimate tire parameters while taking into consideration both states of a vehicle and states of a road environment. A μ gradient detecting circuit detects a μ gradient on the basis of a wheel speed detected by a wheel speed detecting circuit. A gradient value comparing circuit determines a μ gradient section value μr, which is a mean value of the μ gradients from the μ gradient detecting circuit, and calculates a rate (=μr/μI) of the μ gradient mean value μr with respect to a μ gradient initial value μ. A tire temperature estimating circuit stores a table representing the relation between the rate and a tire temperature, and estimates a tire temperature corresponding to the rate calculated by the gradient value comparing circuit as the present tire temperature.

Claims

1. A tire parameter estimation device, the device comprising:

a wheel speed detecting section for detecting a wheel speed;

a road surface friction parameter generating section for generating a road surface friction parameter representing a friction state between a tire of a wheel and a road surface on the basis of the wheel speed detected by the wheel speed detecting section;

a memory section for storing the road surface friction parameter generated by the road surface friction parameter generating section; and

a tire parameter estimation section for estimating at least one tire parameter relating to the tire and the road surface on the basis of the road surface friction parameter stored in the memory section and the road surface friction parameter newly generated by the road surface friction parameter generating section.

2. A tire parameter estimation device according to claim 1, further comprising:

a reference running state detecting section for detecting a reference running state of the vehicle,

wherein the memory section stores the road surface friction parameter at a time at which the reference running state detecting section detects the reference running state, as a reference parameter, and the tire parameter estimating section estimates, as the tire parameter, a tire temperature corresponding to the road surface friction parameter newly generated by the road surface friction parameter generating section by using the characteristics of the tire temperature and the road surface friction parameter with respect to the reference parameter.

3. A tire parameter estimation device according to claim 1, further comprising:

a reference running state detecting section for detecting a reference running state of the vehicle;

a running start detecting section for detecting a start of running of the vehicle on the basis of the wheel speed detected by the wheel speed detecting section; and

a writing section for writing into the memory section the road surface friction parameter generated by the road surface friction parameter generating section each time the running start detecting section detects the start of running of the vehicle and the reference running state detecting section detects the reference running state of the vehicle;

wherein

the tire parameter estimating section estimates a wear amount of the tire as the tire parameter on the basis of a change in a plurality of the road surface friction parameters stored in the memory section.

10. A tire parameter estimation device according to claim 2, wherein the reference running state detecting section detects whether or not the reference running state of the vehicle, on the basis of:

the road surface friction parameter; and

whether or not the vehicle is in a predetermined state.

11. A tire parameter estimation device according to claim 10, wherein the predetermined state of the vehicle is at least one of that:

the vehicle is running substantially straight;

the vehicle is running in a substantially constant speed;

a rotation vibration of the wheel is less than or equal to a predetermined level;

a wiper of the vehicle is not operating; and

a temperature outside the vehicle is more than or equal to a predetermined temperature.

12. A tire parameter estimation device according to claim 1, further comprising:

a reference running state detecting section for detecting a reference running state of the vehicle;

a running start detecting section for detecting a start of running of the vehicle on the basis of the wheel speed detected by the wheel speed detecting section;

a time judging section for judging a time; and

a writing section for writing into the memory section the road surface friction parameter generated by the road surface friction parameter generating section each time the running start detecting section detects the start of running of the vehicle, the reference running state detecting section detects the reference running state of the vehicle, and the time judging section judges a predetermined timing;

wherein

the tire parameter estimating section estimates a wear amount of the tire as the tire parameter on the basis of a change in a plurality of the road surface friction parameters stored in the memory section.

13. A tire parameter estimation device according to claim 1, further comprising:

a reference running state detecting section for detecting a reference running state of the vehicle;

a running start detecting section for detecting a start of running of the vehicle on the basis of the wheel speed detected by the wheel speed detecting section; and

a writing section which can write into the memory section the road surface friction parameter generated by the road surface friction parameter generating section when the running start detecting section detects the start of running of the vehicle and the reference running state detecting section detects the reference running state of the vehicle;

wherein

the tire parameter estimating section estimates a wear amount of the tire as the tire parameter on the basis of a change in a plurality of the road surface friction parameters stored in the memory section.

4. A road surface judgment device, the device comprising:

a vehicle state detecting section for detecting a running state of a vehicle;

a road surface friction state estimating section for estimating a road surface friction state of a road surface on which the vehicle is running, on the basis of the running state of the vehicle detected by the vehicle state detecting section;

a road surface state measuring section for measuring a road surface state of the road surface on which the vehicle is running, on the basis of the running state of the vehicle detected by the vehicle state detecting section and a controlled state of the vehicle;

a referencing section for corresponding the road surface friction state with the road surface state to obtain a reference value;

a reference value changing section for changing the road surface friction state of the reference value to the road surface friction state estimated by the road surface friction state estimating section when the road surface state newly measured by the road surface state measuring section is the same as the road surface state of the reference value; and

a road surface state judging section for judging the road surface state of the road surface on which the vehicle is currently running, on the basis of the road surface friction state newly estimated by the road surface friction state estimating section and the reference value processed through the reference value changing section.

5. A road surface judgment device according to claim 4, wherein the referencing section corresponds the road surface friction state, at a time at which the vehicle is in a predetermined running state, with the road surface state.

6. A road surface judgment device according to claim 4, wherein the referencing section corresponds the road surface friction state, at a time at which the vehicle is running on a predetermined road surface, with the road surface state.

7. A road surface judgment device according to claim 5, wherein the referencing section corresponds the road surface friction state, at a time at which the vehicle is running on a predetermined road surface, with the road surface state.

14. A road surface judgment device according to claim 4, further comprising a memory section for storing the reference value and the reference value changed by the reference value changing section.

8. A road surface judgment device, the device comprising:

a vehicle state detecting section for detecting a vehicle running state;

a receiving section for receiving road surface environment information relating to a reference road surface;

a road surface state estimating section for estimating a road surface state of a road surface on which the vehicle is running, on the basis of the vehicle running state detected by the vehicle state detecting section;

a memory section for storing, as a reference value with respect to the reference road surface, the road surface state estimated by the road surface state estimating section each time the receiving section receives the road surface environment information; and

a judgment section for judging a state of a road surface other than the reference road surface, on the basis of the road surface state estimated by the road surface state estimating section and the reference value with respect to the reference road surface stored in the memory section, when the receiving section does not receive the road surface environment information.

9. A road surface judgment device according to claim 8, wherein the memory section stores the road surface state estimated by the road surface state estimating section at a time at which the vehicle is in a predetermined running state, as the reference value with respect to the reference road surface.

15. A road surface judgment device, the device comprising:

a vehicle state detecting section for detecting a running state of a vehicle;

a road surface friction state estimating section for estimating a road surface friction state of a road surface on which the vehicle is running, on the basis of the running state of the vehicle detected by the vehicle state detecting section;

a road surface state measuring section for measuring a road surface state of the road surface on which the vehicle is running, on the basis of the running state of the vehicle detected by the vehicle state detecting section;

a referencing section for corresponding the road surface friction state with the road surface state to obtain a reference value;

a reference value changing section for changing the road surface friction state of the reference value to the road surface friction state estimated by the road surface friction state estimating section when the road surface state newly measured by the road surface state measuring section is the same as the road surface state of the reference value; and

a road surface state judging section for judging the road surface state of the road surface on which the vehicle is currently running, on the basis of the road surface friction state newly estimated by the road surface friction state estimating section and the reference value processed through the reference value changing section.