ROAD SURFACE FRICTION COEFFICIENT ESTIMATING DEVICE

A road surface friction coefficient estimating device (40; 102) includes an electronic control unit. The electronic control unit is configured to: compute a system noise variance value as an index indicating a degree of variation in a road surface friction coefficient estimation value; compute an observation noise variance value as an index indicating a degree of variation in observation noise; compute, with regard to an observation deviation, an index indicating a degree of shift of the observation deviation that is newly obtained as to an index indicating a degree of past variation in the observation deviation; compute the index as a friction coefficient change amount; compute a Kalman gain; and add in the friction coefficient change amount when computing the system noise variance value. [0002] Selected Drawing: FIG. 3