Road friction coefficients estimating apparatus for vehicle

A road friction coefficient estimating apparatus for a vehicle for estimating friction coefficient of a road surface on which said vehicle travels comprising:

• motion parameter detecting means for detecting motion parameters of said vehicle;
• traveling circumstance recognition means for detecting traveling circumstances and for outputting a recognition signal indicative of said road surface covered with snow;
• low friction coefficient road traveling condition detecting means for detecting a traveling condition indicative of a traveling on said road surface having low friction coefficient;
• low side road friction coefficient estimating means for estimating a low side road friction coefficient according to an adaptive control theory and to a vehicle motion model based on said motion parameters and said traveling condition indicative of a traveling on said road surface having low friction coefficient;
• and
• road friction coefficient estimating means for estimating a road friction coefficient based on said motion parameters, and for rendering said road friction coefficient itself close to said low side road friction coefficient when said recognition signal is inputted.

A method of estimating a road friction coefficient for a road surface, said method comprising:

• detecting a motion parameter for a vehicle;
• detecting a traveling condition indicative of a traveling on said road surface having low friction coefficient;
• estimating a low side road friction coefficient according to an adaptive control theory and to a vehicle motion model based on said motion parameter and said traveling condition indicative of a traveling on said road surface having low friction coefficient;
• and
• estimating said road friction coefficient by comparing an actual yaw rate calculated based on said motion parameter, with a high friction coefficient road reference yaw rate calculated according to said motion parameter and a high road friction coefficient established beforehand and with a low friction coefficient road reference yaw rate calculated according to said motion parameter and a low road friction coefficient.

A friction coefficient estimating apparatus for estimating a friction coefficient of a road surface, said apparatus comprising:

• a motion parameter detector for detecting a motion parameters for a vehicle traveling on said road surface;
• a low friction coefficient traveling condition detector for detecting a traveling condition indicative of a traveling on said road surface having a low friction coefficient;
• a low side friction coefficient estimator for estimating a low side friction coefficient according to an adaptive control theory and to a vehicle motion model based on said motion parameter and said traveling condition indicative of a traveling on said road surface having a low friction coefficient;
• and
• a friction coefficient estimator for estimating said friction coefficient by comparing an actual yaw rate calculated based on said motion parameters, with a high friction coefficient reference yaw rate calculated according to said motion parameters and a high friction coefficient established beforehand, and a low friction coefficient reference yaw rate calculated according to said motion parameters and a low friction coefficient established beforehand.