Method for judging road surface condition and device thereof, and program for judging road surface condition

• US 20050102086A1
• Filed: 10/04/2004
• Published: 05/12/2005
• Est. Priority Date: 11/06/2003
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Nakao, Yukio
• Granted Patent: US 7,512,473 B2
• Time in Patent Office: Days
• US Class Current: 701/80
• 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: 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

Abstract

A judgment method of road surface condition includes steps of: periodically detecting the wheel rotational speeds of the four wheel tires of a vehicle, memorizing the wheel rotational speed of each of tires, determining a slip ratio from said wheel rotational speeds, determining the acceleration or deceleration of the vehicle, determining a relation equation between said slip ratio and the acceleration or deceleration of the vehicle, determining a judgment value for judging a friction coefficient between the road surface and tires based on the slope of said relation equation determined, and setting a threshold which is used for judging the friction coefficient from the judgment value using the information of wireless tags which were buried in the tires.

Claims

1. A method for judging road surface condition comprising the steps of:

detecting periodically rotational speeds of four wheel tires mounted on a vehicle;

memorizing the rotational speed of each tires;

determining a slip ratio from said wheel rotational speeds;

determining acceleration or deceleration of said vehicle;

determining a relation equation between said slip ratio and said acceleration of the vehicle;

determining a judgment value for judging a friction coefficient between road surface and said tires based on slope of said relation equation determined; and

setting a threshold used for judging friction coefficient from said judgment value with information of wireless tags buried in said tires.

2. The method for judging road surface condition of claim 1 further comprising a step of judging abrasion condition of said tires by comparison of said threshold with said judgment value.

3. A device for judging road surface condition comprising:

a wheel speed-detecting means for periodically detecting wheel rotational speeds of four wheel tires of a vehicle;

a memory means for memorizing said wheel rotational speed of each tires;

a slip ratio-calculating means for determining a slip ratio from said wheel rotational speeds;

an acceleration deceleration-calculating means for determining acceleration or deceleration of said vehicle;

a relation equation-calculating means for determining a relation equation between said slip ratio and said acceleration of said vehicle;

a judgment value-calculating means for determining a judgment value for judging a friction coefficient between road surface and tires based on slope of said relation equation determined; and

a threshold-setting means for setting a threshold used for judging friction coefficient from said judgment value with information of wireless tags buried in said tires.

4. The device for judging road surface condition of claim 3 further comprising an abrasion-judging means for judging the abrasion condition of tires by said threshold set.

5. A program for judging road surface condition comprising:

a memory means for memorizing wheel rotational speed of each tires mounted on a vehicle;

a slip ratio-calculating means for determining a slip ratio from said wheel rotational speeds;

an acceleration deceleration-calculating means for determining acceleration or deceleration of said vehicle;

a relation equation-calculating means for determining a relation equation between said slip ratio and said acceleration of the vehicle;

a judgment value-calculating means for determining a judgment value for judging a friction coefficient between road surface and said tires based on slope of said relation equation determined; and

a threshold-setting means for setting a threshold used for judging friction coefficient from said judgment value with information of wireless tags buried in said tires.

6. The program for judging road surface condition of claim 5 further comprising an abrasion-judging means for judging abrasion condition of tires by said threshold set.