Road surface condition estimating apparatus and variation reduction processing apparatus

A road surface condition estimating apparatus comprising:

• a first detector configured to detect a first physical amount related to one of a brake condition and a driving condition of a wheel of a vehicle;
• a second detector configured to detect a vehicle speed of said vehicle;
• a third detector configured to detect a second physical amount which represents a slipperiness and which is determined in accordance with a road surface condition corresponding to a road surface on which said wheel runs, said first physical amount, and said vehicle;
• a reduction processor configured to reduce variations in the second physical amount detected by said third detector in accordance with a change in said first physical amount and to yield a variation-reduced second physical amount;
• a calculator configured to calculate a calculated second physical amount for each of a plurality of predetermined road surface conditions based on the first physical amount and the vehicle speed;
• a comparator configured to compare a detected track of the variation-reduced second physical amount with each of a plurality of calculated tracks of the calculated second physical amount;
• and
• an estimator configured to estimate a road surface condition corresponding to a calculated track selected from said plurality of calculated tracks closest to said detected track among said calculated tracks as being an actual road surface condition corresponding to said road surface on which said wheel runs based on a comparison result of said comparator.

A road surface condition estimating apparatus, comprising:

• means for detecting a plurality of wheel motion amounts, one of said wheel motion amounts related to one of a characteristic of a gradient of a coefficient of friction μ between a wheel and a road surface with respect to a slip speed, a gradient of a braking torque on the wheel with respect to the slip speed, and a gradient of a braking force on the wheel with respect to the slip speed;
• means for correlating at least one detected wheel motion amount of said plurality of wheel motion amounts with a converted wheel motion amount for each of a plurality of road surface conditions based on a correlation between said at least one detected wheel motion amount and each of a plurality of road surface conditions;
• and
• means for estimating a road surface condition through comparison of said converted wheel motion amount with a further detected wheel motion amount of the plurality of wheel motion amounts.

A device for estimating a road condition, comprising:

• a plurality of inputs configured to receive a plurality of detected wheel motion amounts describing the behavior of a vehicle during operation;
• correlation information describing a relationship between at least one of said plurality of detected wheel motion amounts and a plurality of possible road conditions, said correlation information being characteristic of a gradient of a coefficient of friction between a tire and a road surface;
• a storage device configured to store said correlation information;
• a processor configured to process said some of said plurality of detected wheel motion amounts in light of said correlation information to yield a processed wheel motion amount for each of said possible road conditions;
• a comparator configured to compare each of said processed wheel motion amounts with a particular detected wheel motion amount selected from said plurality of detected wheel motion amounts and output a plurality of comparison results;
• and
• a selector configured to select a most relevant comparison result from said plurality of comparison results and to output a signal that indicates a most relevant road condition based upon said most relevant comparison result.