Patent ID: 6522968
Filing Date: 2003-02-18
Classification: B60T

Abstract:
A device, for use with a vehicle having wheels, for estimating a road friction state, said device comprising:a sensor which detects a wheel speed signal; a filter which receives the signal and passes a portion of the wheel speed signal having a frequency within a predetermined range, the range including at least one resonance point or at least one antiresonance point; a computer which computes a physical amount expressing a magnitude of vibration of a wheel, on the basis of the portion of the wheel speed signal passed by the filter; an estimator which estimates a physical amount expressing ease of slippage of the wheel, on the basis of the portion of the wheel speed signal passed by the filter; and a road friction state estimator which estimates a friction state of the wheel with respect to a road surface, on the basis of the physical amount expressing the magnitude of the vibration of the wheel computed by the computer and the physical amount expressing the ease of slippage of the wheel estimated by the estimator.