Method and apparatus for estimating road surface state and tire running state, ABS and vehicle control using the same

A road condition and tire running state estimation apparatus comprising:

• vibration detection means for detecting a vibration of a tire or a wheel of a running car;
• means for detecting a vibration level in a frequency band in a frequency range of at least 10 to 10,000 Hz of a frequency spectrum obtained by analyzing the frequency of the detected vibration;
• and
• means for estimating a condition of a road at the time of running, and a running state of the tire, from the detected vibration level
• wherein the vibration detection means is mounted on the same substrate, or in the same housing, as a pressure sensor for monitoring a pressure of a gas filled in the tire.

A road condition and tire running state estimation apparatus comprising:

• vibration detection means for detecting a vibration of the suspension of a running car;
• means for detecting a vibration level in a frequency band in a frequency range of at least 10 to 10,000 Hz of a frequency spectrum obtained by analyzing the frequency of the detected vibration;
• and
• means for estimating a condition of a road at the time of running, and a running state of the tire, from the detected vibration level.

A road condition and tire running state estimation apparatus comprising:

• pressure change detection means for detecting a change in the pressure of a gas filled in a tire of a running car;
• means for detecting a pressure change level in a frequency band in a frequency range of at least 10 to 10,000 Hz of a pressure change spectrum obtained by analyzing the frequency of the detected pressure change;
• and
• means for estimating a condition of a road at the time of running, and a running state of the tire, from the detected pressure change level.

An ABS brake control method comprising:

• detecting at least one of a tire vibration, a wheel vibration, a suspension vibration and a change in the inside pressure of a tire;
• detecting a vibration level of a vibration spectrum or a pressure change level of a pressure change spectrum obtained by analyzing the frequency of the vibration or the pressure change to estimate a road friction coefficient continuously;
• and
• changing a threshold value of an oil pressure of a brake for shifting to ABS control according to the estimated value of road friction coefficient right before a driver steps on the brake.

An ABS brake control method comprising:

• detecting at least one of a tire vibration, a wheel vibration, a suspension vibration and a change in the inside pressure of a tire;
• detecting a vibration level of a vibration spectrum, or a pressure change level of a pressure change spectrum, obtained by analyzing the frequency of the vibration or the pressure change to estimate a road friction coefficient continuously;
• and
• adjusting a change in the oil pressure of an ABS brake according to the estimated value of road friction coefficient right before a driver steps on the brake.

An ABS brake control apparatus comprising:

• means for detecting at least one of a tire vibration, a wheel vibration, a suspension vibration and a change in the inside pressure of a tire;
• means for detecting a vibration level of a vibration spectrum or a pressure change level of a pressure change spectrum obtained by analyzing the frequency of an information signal indicative of the detected vibration or the detected pressure change to calculate the estimated value of a road friction coefficient continuously as=1/[1+exp{−(a0+a1x1+a2x2+ . . . +anxn)}], wherein a0 is a constant, a1, a2, . . . and an are coefficients and xi is a vibration level or pressure change level at a frequency band (fi);
• means for detecting the ON/OFF state of a brake switch;
• and
• means for changing a threshold value of an oil pressure of a brake for shifting to ABS control according to the estimated value of the road friction coefficient right before a driver steps on the brake.

An ABS control apparatus comprising:

• means for detecting at least one of a tire vibration, a wheel vibration, a suspension vibration and a change in the inside pressure of a tire;
• means for detecting a vibration level of a vibration spectrum or a pressure change level of a pressure change spectrum obtained by analyzing the frequency of an information signal indicative of the detected vibration or the detected pressure change to calculate the estimated value of a road friction coefficient continuously as=1/[1+exp{−(a0+a1x1+a2x2+ . . . +anxn)}], wherein a0 is a constant, a1, a2, . . . and an are coefficients and xi is a vibration level or pressure change level at a frequency band (fi);
• means for detecting the ON/OFF state of a brake switch;
• and
• means for adjusting a change in the oil pressure of an ABS brake according to the estimated value of the road friction coefficient right before a driver steps on the brake.