| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric power steering device capable of precisely determining a straight movement state of a vehicle and capable of calculating a central point of a steering angle with high accuracy. SOLUTION: A CPU11 calculates an axial force F balanced with an external force applied to a rack bar 34 by totaling a steering torque MT acting on a steering shaft 33 and an assist torque AT generated by an electric motor 30. The CPU 11 determines the straight movement state of the vehicle on the basis of a steering angleθ, a vehicle speed V and the axial force F. Thus, even in such a state that the central point of a control steering angle is displaced, and the torque is provided so that a driver replaces a steering wheel 31 at a neutral position, the straight movement state is determined by using the axial force F acting on the rack bar 34 to precisely determine the straight movement state. The CPU 11 calculates the central point of a smoothing steering angle by using the central point of an instantaneous steering angle in the straight movement state which is precisely determined to determine the extremely precise central point of the control steering angle. COPYRIGHT: (C)2006,JPO&NCIPI |
