VEHICULAR STEERING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a vehicular steering device capable of eliminating any unnecessary intervention of the IFS control in an area in which the vehicular stability is slightly degraded on a high-μroad, and performing the IFS control only in a condition in which a vehicle of degraded degree of grip is unstable. SOLUTION: A first ECU 30 detects the steering torque on a steering system, the self-aligning torque generated in a front wheel is estimated based on the steering torque, and the side force on the front wheel is estimated based on the lateral acceleration and the yaw rate. The first ECU 30 estimates the degree of gripεto the front wheel based on the change in the self-aligning torque to the side force. The first ECU 30 determines whether or not the grip degree is below the 20S (over-steer). A second ECU 40 controls the transmission ratio according to the vehicle condition when the degree of grip is below the 20S starting threshold. COPYRIGHT: (C)2005,JPO&NCIPI