Patent ID: 6898966

Claim:
A road surface friction state estimating apparatus comprising: a self aligning torque estimating portion which estimates self aligning torque applied to a tire; a slip angle estimating portion which estimates a slip angle of the tire; a high pass filter which performs high pass filter processing on the slip angle estimated by the slip angle estimating portion; a lateral force calculating portion which calculates a lateral force applied to the tire; a slip angle converting portion which converts the lateral force calculated by the lateral force calculating portion into a slip angle; a low pass filter which performs low pass filter processing on the slip angle obtained by conversion by the slip angle converting portion; a summing portion which sums the slip angle on which the high pass filter processing has been performed by the high pass filter and the slip angle on which the low pass filter processing has been performed by the low pass filter; and a road surface friction state estimating portion which estimates a road surface friction state based on the slip angle obtained by summation by the summing portion and the self aligning torque estimated by the self aligning torque estimating portion.