| 摘要 |
PURPOSE:To moderate the degree of responsiveness in a car and make improvements in convergeability and driving stability, by steering rear wheels farther in the same phase direction than in time of the other steering wheel operations, when wheeling around for a lane alteration in case of a four-wheel drive vehicle. CONSTITUTION:At the time of steering wheel operation other than a lane lateration, a characteristic selecting part 36 selects a steeting ratio characteristic B from a characteristic memory part 30. And, a desired steering angle is calculated by a desired steering angle operational part 31 of a steering ratio variable device 34, whereby each steering angle of front and rear wheels is variably controlled, and rear wheels are steered in opposite phase to front wheels at the time of low speed but at the time of high speed, they are steered in the same phase. In case of the lane alteration, when a steering wheel is made to wheel around from steerage in a lane altering direction to the opposite direction, the characteristic selecting part 36 receives an output signal out of a wheel-around state detecting device 35, selecting a steering ratio characteristic A from the characteristic memory part 30, and is variably controlled by the steering ratio variable device 34. Since the steering ratio characteristic A is shifted to the same phase side as compared with the steering ratio characteristic B, rear wheels are steered in the same phase direction as front wheels. |
