Anti-skid controller having accurate road surface detection capabilities
First Claim
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1. An anti-skid controller comprising:
- wheel braking force application means for applying a braking force to a wheel of a vehicle;
wheel acceleration detection means for generating a wheel acceleration signal representative of a wheel acceleration of said wheel of said vehicle;
high frequency component extraction means for extracting high frequency components no less than 20 Hz of said wheel acceleration signal, said high frequency component extraction means including a differential filter unit for extracting said high frequency components by first extracting low-frequency components of said wheel acceleration signal and then subtracting said low-frequency components from said wheel acceleration signal;
dispersion condition detection means for determining a dispersion value indicative of a dispersion condition of said high frequency components;
road surface condition detection means for determining a road surface condition based on said dispersion value;
setting means for setting a control reference for adjusting said braking force applied to said wheel based on a vehicle speed of said vehicle;
pressure adjustment means for adjusting said braking force applied to said wheel based on said control reference; and
correction means for correcting said control reference based on said road surface condition.
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Abstract
The wheel speed of each wheel of a vehicle is calculated based on wheel speed signals from wheel speed sensors. The wheel acceleration of each wheel is calculated based on the wheel speed. High frequency components of the wheel acceleration of each wheel are filtered using a high-pass filter to obtain the frequency components of the wheel acceleration which are due only to the road surface condition. Then, a variance of the filtered wheel acceleration is calculated, and a bad road condition determination is executed using the calculated variance. Anti-skid control is carried out based on the bad road condition determination result to provide improved braking control in off-road conditions.
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Citations
14 Claims
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1. An anti-skid controller comprising:
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wheel braking force application means for applying a braking force to a wheel of a vehicle; wheel acceleration detection means for generating a wheel acceleration signal representative of a wheel acceleration of said wheel of said vehicle; high frequency component extraction means for extracting high frequency components no less than 20 Hz of said wheel acceleration signal, said high frequency component extraction means including a differential filter unit for extracting said high frequency components by first extracting low-frequency components of said wheel acceleration signal and then subtracting said low-frequency components from said wheel acceleration signal; dispersion condition detection means for determining a dispersion value indicative of a dispersion condition of said high frequency components; road surface condition detection means for determining a road surface condition based on said dispersion value; setting means for setting a control reference for adjusting said braking force applied to said wheel based on a vehicle speed of said vehicle; pressure adjustment means for adjusting said braking force applied to said wheel based on said control reference; and correction means for correcting said control reference based on said road surface condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification