Wheel attitude control method and wheel attitude control device

• US 8,160,775 B2
• Filed: 12/16/2008
• Issued: 04/17/2012
• Est. Priority Date: 12/26/2007
• Status: Expired due to Fees

• Current Assignee: Yokohama Rubber Company Limited
• Original Assignee: Yokohama Rubber Company Limited
• Inventors: Kitazaki, Tsuyoshi, Matsuda, Jun, Miyashita, Naoshi
• Primary Examiner(s): Black, Thomas
• Assistant Examiner(s): Lewandroski, Sara
• Application Number:
  US12/336,322
• Publication Number:
  US 20090171531A1
• Time in Patent Office: 1,218 Days
• Field of Search: 701/37, 701/70, 701/79, 701/29, 731/46, 734/88, 280/5.5, 152/151, 152/209.1
• US Class Current: 701/37
• CPC Class Codes: B60G 17/0164 mainly during accelerating or braking
• CPC Class Codes: B60G 17/01908 Acceleration or inclination sensors characterised by the use of gyroscopes B60G21/08
• 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 2200/46 camber angle
• CPC Class Codes: B60G 2200/462 Toe-in/out
• CPC Class Codes: B60G 2204/113 Tyre related sensors
• CPC Class Codes: B60G 2400/05 Attitude
• CPC Class Codes: B60G 2400/10 Acceleration; Deceleration
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/1042 using at least two sensors
• CPC Class Codes: B60G 2400/39 Brake pedal position
• CPC Class Codes: B60G 2401/10 Piezoelectric elements
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/60 Signal noise suppression; Electronic filtering means
• CPC Class Codes: B60G 2800/22 Braking, stopping
• CPC Class Codes: B60G 2800/912 Attitude Control; levelling control
• 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: B62D 17/00 Means on vehicles for adjusting camber, castor, or toe-in

Abstract

A wheel attitude control method of the invention comprises the steps of: chronologically obtaining acceleration data in a radial direction of a tire at a center position of a tire tread and at an off-center position spaced apart from the center position toward a shoulder; obtaining respective contact lengths at the center position and the off-center position from the acceleration data; and controlling a wheel attitude, which varies in accordance with changes in a load applied to the wheel when the braking force is imparted to the wheel, based on the obtained contact length at the center position and the obtained contact length at the off-center position.

Claims

1. A wheel attitude control method for controlling an attitude of a wheel when braking a vehicle by imparting a braking force to the wheel attached to the vehicle, the method comprising the steps of:

chronologically obtaining acceleration data in a radial direction of a tire at a center position of a tire tread and at an off-center position spaced apart from the center position toward a shoulder on a vehicle inner side of the tire;

imparting the braking force to the wheels attached to the vehicle;

obtaining respective contact lengths at the center position and the off-center position until a speed of the wheel detected by a wheel speed sensor is lowered to a given value from the braking force imparted to the wheel based on a leading edge peak value V₁ and a trailing edge peak value V₂ detected from the acceleration data, the leading edge peak value V₁ referring to a value of a leading edge peak P₁ where an acceleration first attains its maximum level during one rotation of the wheel, the trailing edge peak value V₂ referring to a value of a trailing edge peak P₂ where after the leading edge peak P₁, from a temporary reduction in the value of the acceleration, the acceleration again attains another maximum value;

calculating a difference or a ratio between the obtained contact length at the center position and the obtained contact length at the off-center position,

comparing the calculated difference with a pre-set first threshold value or comparing the calculated ratio with a pre-set second threshold value, and

controlling a wheel attitude, which varies in accordance with changes in a load applied to the wheel, based on the calculated difference or the calculated ratio in contact length when the calculated difference exceeds the first threshold value or the calculated ratio exceeds the second threshold so that a contact patch shape of the tire is caused to approximate a contact patch shape at the time of imparting no braking force, until the speed of the wheel detected by the wheel speed sensor is lowered to the given value.

2. The wheel attitude control method according to claim 1, wherein the wheel attitude is controlled by controlling a camber angle or a toe angle of the wheel is controlled in the wheel attitude controlling step.

3. The wheel attitude control method according to claim 1, wherein the off-center position is situated within a range of 25% of a tire contact width as measured from a contact width end in a tire width direction.

4. A wheel attitude control device for controlling an attitude of a wheel when braking a vehicle by imparting a braking force to the wheel attached to the vehicle, the device comprising:

acceleration data obtaining means for chronologically obtaining acceleration data in a radial direction of a tire at a center position of a tire tread and at an off-center position spaced apart from the center position toward a shoulder on a vehicle inner side of the tire;

a brake sensor to trigger calculation of contact lengths;

a wheel speed sensor to detect a wheel speed;

contact length obtaining means for obtaining respective contact lengths at the center position and the off-center position until a speed of the wheel detected by the wheel speed sensor is lowered to a given value from the braking force imparted to the wheel based on a leading edge peak value V₁ and a trailing edge peak value V₂ detected from the acceleration data, the leading edge peak value V₁ referring to a value of a leading edge peak P₁ where an acceleration first attains its maximum level during one rotation of the wheel, the trailing edge peak value V₂ referring to a value of a trailing edge peak P₂ where after the leading edge peak P₁, from a temporary reduction in the value of the acceleration, the acceleration again attains another maximum value;

control judgment means for calculating a difference or a ratio between the obtained contact length at the center position and the obtained contact length at the off-center position and comparing the calculated difference with a pre-set first threshold value or comparing the calculated ratio with a pre-set second threshold value, and

control signal generating means for generating a control signal for controlling the wheel attitude, which varies in accordance with changes in a load applied to the wheel, based on the calculated difference or the calculated ratio in contact length when the calculated difference exceeds the first threshold value or the calculated ratio exceeds the second threshold in accordance with result of the comparison by the control judgment so that a contact patch shape of the tire is caused to approximate a contact patch shape at the time of imparting no braking force until the speed of the wheel detected by the wheel speed sensor is lowered to the given value.